Push-Pull BJT Slayer Exciter - Page 1
Forum section: electronics / projects

author: lobster
author_rank: Contributor
timestamp: May 19, 2025, 09:49:45 pm
content: Dear fellow electronics nerds:This is my first post here soplease go easyon me.I am designing a Slayer Exciter and I am hoping I may share the schematic and get your opinions on whether it makes sense. For instance, are items wired where and how they should be?The total distinct component count is around 30 and total component count (including multiples of the same) is around 54. I should finish with the schematic within the next week. Any particular protocol for how to post a schematic of this sort?Also, as a heads up, I loathe electrolytic capacitors and have spare 100 uF film caps on hand so if you're wondering why I'm using those, that's why.Thanks in advance!Truly,Lobster from Floriduh

author: ejeffrey
author_rank: Super Contributor
timestamp: May 20, 2025, 02:02:49 am
content: Thanks for asking! Most people don't. That's already a good sign.1) post a reasonable scaled standard image format, not a schematic file from your eda tool. Nobody wants to download your files and take sure they have the right program installed. The schematic and any labels should be easily legible, don't scale it so everything is blurry.2) organize and label your schematic to the best of your ability. Things that are ok when it's just for your use are not when you are asking other people to review your work. If you can spent 10 minutes of cleanup to save each person looking at it 1 minute trying to understand it shows respect for the time of people helping you. In addition the faster people can decode your schematic the more likely they are to put in the effort to help you.3) be prepared for criticism. Not that anyone here should attack you or be aggressive. But a lot of times people ask for feedback and then argue when they get it, like they already knew the answer they were fishing for. That's just a waste of everyone's time.

author: SteveThackery
author_rank: Super Contributor
timestamp: May 20, 2025, 10:24:07 am
content: Quote from: lobster on May 19, 2025, 09:49:45 pmThe world of electronics engineering is rooted in physics and has room only for logic and rational thinking. To "loathe" a particular type of capacitor is irrational and illogical, and you need to get over it. Open up any piece of electronics and you will find electrolytics - they are not "loathed" by real electronic engineers, they are used when it is appropriate and not when it isn't.Electrolytics are just like every other type of capacitor, and just like every other electronic component: they have a set of characteristics that make them the best choice for some purposes, and not the best choice for others. That is true of ceramics, film caps, junction transistors, op-amps, anything you can name.Be rational, be logical, and see every electronic component for what it is: an item on a menu, to be selected when it meets the requirements. No more, no less.

author: lobster
author_rank: Contributor
timestamp: May 20, 2025, 07:18:16 pm
content: Thank you. I much appreciate your prompt reply and pointers. One never knows when stepping onto unfamiliar ground whether responses will be unnecessarily snarky or helpful. Thanks again!Quote from: ejeffrey on May 20, 2025, 02:02:49 am

author: lobster
author_rank: Contributor
timestamp: May 20, 2025, 07:20:58 pm
content: My friend, in the land of capitalism, the dollar is king. I vote with my wallet and have never needed to design anything with electrolytics. There have always been preferred alternatives. I have my reasons while respecting that others likely feel differently. Thanks for your thoughts.Quote from: SteveThackery on May 20, 2025, 10:24:07 am

author: TimFox
author_rank: Super Contributor
timestamp: May 20, 2025, 09:17:05 pm
content: Quote from: lobster on May 20, 2025, 07:20:58 pmHave you never needed a capacitor (e.g., rectifier filter) on the order of 1000 uF?

author: SteveThackery
author_rank: Super Contributor
timestamp: May 20, 2025, 10:53:35 pm
content: Quote from: lobster on May 20, 2025, 07:20:58 pmYou've done it again. Think, don't feel, if you want to be a good engineer.

author: lobster
author_rank: Contributor
timestamp: May 21, 2025, 12:52:56 am
content: Yes. In such instances, I wire ten 100 uF caps in parallel. As they say, "go big or go home."Quote from: TimFox on May 20, 2025, 09:17:05 pm

author: lobster
author_rank: Contributor
timestamp: May 21, 2025, 12:53:33 am
content: I'm sorry youfeelthat way.Quote from: SteveThackery on May 20, 2025, 10:53:35 pm

author: Analog Kid
author_rank: Super Contributor
timestamp: May 21, 2025, 01:01:42 am
content: I'm curious: what, exactly, is your objection to using electrolytic capacitors?I understand the issues with those components, although today there exist electrolytic caps that don't exhibit the gross problems that plagued those of the past.

author: lobster
author_rank: Contributor
timestamp: May 21, 2025, 02:05:33 am
content: I don't know why this thread has been so focused on my preference to avoid electrolytics like I would Ebola. Regardless, to answer your question, one blew up and killed my beloved Ampy, my pet Japanese Dwarf Flying Squirrel. I remember when he first hatched from his little squirrel egg and gave me a hug and a kiss.In all seriousness, I don't care for the overarching design in that they use a liquid electrolyte which may evaporate. Their lifespans are generally shorter than alternatives. They aren't well suited to high frequencies due to relatively high ESR and ESL. They often have a higher leakage current compared to alternatives. In the event of overvolting, they can burst. (Back in the day, they burst for giggles even when operated below their rated voltage.) ESR and component lifespan are temperature dependent more so than with other options. Simply storing them over long periods of time, they may lose a meaningful degree of capacitance. Most are polarized / directional whereas a number of alternatives are not. I am also old enough to remember what happened to Abit in the early 2000s.So, in short, I am not a fan. I have never needed to design a circuit with electrolytics. So long as there are alternatives with which I am more comfortable, that's what I'll continue to use. The "no real" [fill in the blank] logical fallacy does little to illustrate the error of my ways or persuade me to give electrolytics another chance. If you don't want a red car, buy a blue one. If you don't want a car with a combustion engine, buy an electric car. If you don't want a house with shingles, buy one with metal or tile roofing. In life, there are often many choices. The only minimal annoyance this particular choice has caused me has been limited to sorting through a couple of superfluous replies on this thread. Not a big deal in the scheme of things.If youlikeusing electrolytics, go for it. If you don'tliketo use them, don't. I'm not trying to convince anyone to change their standard operating procedure. I simply wanted to articulate, from the outset, I have a preference and that it is an intentional one so that no one wastes time recommending I swap out caps for electrolytics to save a couple of bucks. I simply wanted to be respectful of everyone's time.#RIPampyQuote from: Analog Kid on May 21, 2025, 01:01:42 am

author: MariuszD
author_rank: Regular Contributor
timestamp: May 21, 2025, 07:41:26 am
content: Show us the schematic. Than capacitor offtopic will end. I like to use better components when it is possible but for 2200uF 450V for 10000uF 40V there is no replacement. Sometimes high ESR is beneficial. Leakage current is irrelevant in power circuits. Often bleeder resistors must be added. Some 50 years old devices have all electolytics in perfect condition.

author: SteveThackery
author_rank: Super Contributor
timestamp: May 21, 2025, 12:43:44 pm
content: Quote from: lobster on May 21, 2025, 02:05:33 amOh my god, we've got a right one here. There is no "want"! There is "Is this the best fit for the requirements? Yes/No". That's all.Quote from: lobster on May 21, 2025, 02:05:33 amAnd again: there is no 'like'. There is.... Oh, well, you get the idea. (Actually I don't suppose you do.)This is me advocating for purely rational thinking in a purely engineering discipline. That's it from me, I promise. Back to the topic.....

author: lobster
author_rank: Contributor
timestamp: May 21, 2025, 02:13:47 pm
content: Is that a challenge, my dear sir?Quote from: SteveThackery on May 21, 2025, 12:43:44 pm

author: SteveThackery
author_rank: Super Contributor
timestamp: May 21, 2025, 07:15:56 pm
content: Quote from: lobster on May 21, 2025, 02:13:47 pmNo, a promise.You asked about how to post a schematic, but then talked about whether items are wired where and how they should be. Does this mean you want to post a wiring diagram as well as a schematic? Or is it a PCB you're designing?I ask because there are plenty of apps for producing schematics, but not so much for wiring diagrams. For example, I recommend you take a look at KiCAD because it has a reasonable schematic editor, a built-in circuit simulator to help check your design, and a PCB design tool, all integrated into one product and free to use.A couple of things about posting your schematic. Firstly, don't post a proprietary file format; it is better to post a PNG or other format that doesn't use lossy compression. That's because many people won't be able read a proprietary file type. If your schematic app doesn't have an "export to PNG" option you can always do a screen grab.Secondly, resist the temptation to cover the workspace with lots of sub-circuits in rectangular boxes, with labels to show the connections. It makes it extremely difficult to understand such a schematic, because the viewer has to keep a mental map of where every label is in order to work out the connections. Obviously sometimes it really is necessary to do that, but where possible joining things with wires is a big help to the people trying to help you.In terms of the layout of the schematic at a high level, in general power currents flow top to bottom, and signals flow left to right. Don't invert ground symbols.Hit the "Attachments and other options" button to attach your schematic.

author: lobster
author_rank: Contributor
timestamp: May 23, 2025, 01:57:01 am
content: Totally fair point, Steve. I apologize for being imprecise and overly colloquial in my terminology. I would like to post the schematic, not a wiring diagram or the PCB layout. I will work on PCB layout after I have a chance to confirm the schematic is in good order.I will post the schematic once it is in a more polished state. I wish to first make sure that I post something which strikes me as largely in order so that I don't waste anyone's time critiquing or revising something I could have picked up on, myself, had I spent a few more minutes checking it over.Thanks for your patience.Quote from: SteveThackery on May 21, 2025, 07:15:56 pm

author: lobster
author_rank: Contributor
timestamp: May 23, 2025, 09:53:42 pm
content: Please see my draft schematic attached at the end of this post. I am going to add some more test points by the transistors and the power input but I wanted to upload the general design to make sure it is sound before getting too much more into the design. USB-IC supports 20V 3A. If you have any question as to why I've included specific components, please let me know. I'll reply with my thoughts.Item Quantity Designator Manufacturer Name Manufacturer PN Description1 2 C1, C2 EPCOS - TDK Electronics B32526R0107K000 CAP FILM 100UF 10% 63VDC RADIAL2 3 C3, C8, C11 Panasonic ECW-FD2J104J4 CAP FILM 0.1UF 5% 630VDC RADIAL3 2 C4, C7 TDK Corporation CGA5L4NP02J103G160AA 10000 pF ±20% 630V Ceramic Capacitor C0G, NP0 1206 (3216 Metric)4 1 C5 Murata Electronics GRM21BR61C106KE15K CAP CER 10UF 16V X5R 08055 3 C6, C9, C10 TDK C3216X7R1H105K160AE CAP CER 1UF 50V X7R 12066 3 D1, D2, D3 Taiwan Semiconductor Corporation MBRF30200CTHC0G Diode Array 1 Pair Common Cathode Schottky 200 V 30A Through Hole TO-220-3 Full Pack, Isolated Tab7 1 F1 Littelfuse Inc. 0618005.MXP FUSE GLASS 5A 250VAC 5X20MM8 2 HS1, HS2 Wakefield Thermal OMNI-UNI-34-50 HEATSINK TO-247 TO-264 TO-2209 1 J1 Switchcraft Inc. L721RAHLP LOW PROFILE RAPC MOUNT DC POWER10 2 J2, J3 Molex 47053-3000 Connector Header Through Hole 4 position 0.100" (2.54mm)11 2 J5, J6 Phoenix Contact 1714971 2 Position Wire to Board Terminal Block Horizontal with Board 0.375" (9.53mm) Through Hole12 3 L1, L2, L3 Bel Signal HTTI-47-5.6 47 µH Shielded Toroidal Inductor 5.6 A 36mOhm Max Vertical, No Base, 2 PC Pin13 1 LED1 ams OSRAM KB DELPS2.12-QHRI-24-Z555-10-S Blue 466nm LED Indication - Discrete 2.95V 2-SMD, Flat Leads14 1 Q1 Toshiba TTA1452B,S4X TRANS PNP 80V 12A TO-220SIS15 1 Q2 Toshiba Electronic Devices & Storage Corp. TTC3710B,S4XS Toshiba TTC3710B,S4X(S NPN Transistor, 12 A, 80 V, 3-Pin TO-220SIS16 2 R1, R4 Bourns PCW1D-B16-KAB103L Potentiometers 10K 20% Sq 22mm Single Turn17 1 R2 Rohm Semiconductor SDR03EZPJ222 RES SMD 2.2 KOHM 5% 0.3W 060318 2 R3, R6 Bourns Inc. CR2512-FX-1001ELF RES SMD 1K OHM 1% 1W 251219 2 R5, R7 TT Electronics W22-10KJI RES 10K OHM 7W 5% AXIAL20 1 R8 KOA Speer Electronics, Inc. RK73H1JTTD1002F RES 10K OHM 1% 1/10W 060321 3 SW1, SW2, SW3 NKK MN11SS1W03 Single-Pole, Single-Throw Switch22 2 TP1, TP2 Keystone Electronics 5000 PC TEST POINT MINIATURE RED23 3 TVS1, TVS2, TVS3 Texas Instruments TVS2701DRBR 27-V bidirectional flat-clamp surge protection device24 1 U1 STMicroelectronics STUSB4500QTR USB Controller USB 2.0 I2C Interface 24-QFN (4x4)25 1 USB_CONN Amphenol ICC (Commercial Products) 124019282112A USB TYPE C, RECEPTACLE, TOP MOUNEdit: C5 may be removed or changed. I don't know how this part ended up getting mixed into my BOM. It may have been a mistake. I will review this shortly.

author: lobster
author_rank: Contributor
timestamp: May 24, 2025, 10:21:36 pm
content: Okay. I got C5 figured out. It should have been a ceramic with the following specs:Capacitance: 10 uFVoltage Rating DC: 50 VDCDielectric: X8LTolerance: 10 %Maximum Operating Temperature: + 150 CI'm not going to repost the schematic for this single change but I wanted to mention it before anyone replies. Thanks!

author: TimFox
author_rank: Super Contributor
timestamp: May 24, 2025, 10:41:57 pm
content: With 20 V DC bias, what is the capacitance of C5 (10 uF/50 V/X8L)?

author: lobster
author_rank: Contributor
timestamp: May 24, 2025, 10:46:43 pm
content: Tim, thanks for your reply. While the capacitance of ceramic capacitors may be impacted by voltage, running 20V DC on a capacitor rated to 50V DC with a 10% tolerance, I would expect no more than a 10% drift from the rated 10 uF. I apologize if I am misunderstanding your question or if there is some aspect of this which is presently lost on me. I don't claim to be a pro. Thanks!Quote from: TimFox on May 24, 2025, 10:41:57 pm

author: TimFox
author_rank: Super Contributor
timestamp: May 24, 2025, 11:04:07 pm
content: Quote from: lobster on May 24, 2025, 10:46:43 pmI'm not familiar with X8L dielectric, but "X" dielectrics have a substantial (negative) voltage co-efficient of capacitance.Do you have the datasheet for that device? It should show the capacitance as a function of bias voltage. Besides dielectric, it also depends on the physical dimensions.

author: lobster
author_rank: Contributor
timestamp: May 24, 2025, 11:20:18 pm
content: Tim, I'm attaching a data sheet for the component. The specific model capacitor is CL32E106KBVVPOE. Thanks again!Quote from: TimFox on May 24, 2025, 11:04:07 pm

author: TimFox
author_rank: Super Contributor
timestamp: May 25, 2025, 02:52:46 am
content: Unfortunately, that long brochure of "automotive" capacitors does not discuss the change in capacitance with voltage for these parts.However, the dieledtric is "Class II", and therefore will have a noticeable voltage co-efficient.

author: lobster
author_rank: Contributor
timestamp: May 25, 2025, 02:28:40 pm
content: Having communed with the capacitor spirits, I have been provided the following rough data:Estimated DC bias derating curves for CL32E106KBVVPOE (based on Samsung and industry data) suggest:At 20V: ~80–85% of rated capacitance.At my 20V V_SYS rail (from USB-C negotiation), the effective capacitance of the Samsung X8L 10µF 50V MLCC will likely be around 8µF–8.5µF. For decoupling, this appears adequate.Quote from: TimFox on May 25, 2025, 02:52:46 am

author: TimFox
author_rank: Super Contributor
timestamp: May 25, 2025, 02:40:32 pm
content: That should work. Since that line of capacitors is marketed for automotive purposes, the large brochure concentrated on relevant conditions such as vibration.What estimate did you find for capacitance decrease at full rated voltage?

author: lobster
author_rank: Contributor
timestamp: May 25, 2025, 02:56:25 pm
content: At 0V: ~100% rated capacitance (10µF).At 10V: ~90–95% of rated capacitance.At 20V: ~80–85% of rated capacitance.At 30V: ~70–75% of rated capacitance.At 40V: ~60–70% of rated capacitance.At50V:~50–60%of rated capacitance.I must admit, I am surprised by how severely the capacitance decreases with increasing voltage.Quote from: TimFox on May 25, 2025, 02:40:32 pm

author: TimFox
author_rank: Super Contributor
timestamp: May 25, 2025, 03:12:57 pm
content: That’s not bad for a Class II dielectric in a SMT capacitor.Z5U is much worse.One of the trade-offs for using high dielectric constant materials to achieve a reasonable size for large capacitance is the non-linear behavior.The linear dielectrics such as C0G are not practical for capacitance above 1 uF in a sensible size.

author: lobster
author_rank: Contributor
timestamp: May 25, 2025, 04:04:49 pm
content: Does the schematic make sense from a high level? Do any components appear superfluous or insufficient? Are they any you would add? I don't want to skyrocket complexity but if there's a smart addition or two, I'm open to suggestions. As to L2 and L3, does it make sense to include these inductors as shown? For L2, on the secondary side, I added it to serve as an EMI filter to prevent high frequency noise from passing beyond the secondary coil. As to L3, on the primary side, I added it to keep high frequency switching noise from coupling back into the main V_SYS rail. Will this truly help tor am I nuts for one or both of these additions? Any other thoughts?

author: Paul Price
author_rank: Super Contributor
timestamp: May 25, 2025, 04:58:48 pm
content: I have perused your schematic and I have a bad feeling how your circuit could possibly work at all?What does your circuit do?Have you breadboarded this circuit to see if it works?Why does your circuit work at all?How does your circuit work to function as a Slayer Exciter?Could you please tell everyone with a few but sufficient words how and why you think your individual circuit functional boxes work together and how you would choose these ic's to make things work?Specifically,Power Status led indicator: What's the need for a pot?Power Supply seems to duplicate the function of D1 with D2?Oscillator: Shorts power to ground trough the primary coil? Doesn't look anything like a push-pull oscillator.I have a strong feeling your circuit would be smokey and I do not feel right about it at all.

author: lobster
author_rank: Contributor
timestamp: May 25, 2025, 05:34:02 pm
content: As requested, I will try to keep the response succinct.How it works and how it functions as a Slayer Exciter:Oscillator Stage: Two transistors form a feedback loop. They switch on and off, creating a high-frequency AC signal.Transformer Effect: This AC drives the primary coil. The secondary coil is loosely coupled, picking up energy from the primary coil's magnetic field.Resonance Boosts Voltage: The secondary coil has its own natural frequency. When the oscillator’s frequency matches this, the voltage builds up well beyond input voltage.Why it works:• The transistors make the AC.• The coils transfer the energy.• Resonance multiplies the voltage.I have not yet breadboarded it as I am trying to first confirm my schematic does not have any glaring issues.I've essentially expanded on a basic Slayer Exciter by adding passive cooling for transistors and the opportunity to add active cooling in the form of 24V fans, a complementary second transistor, offering two power input options, adding protection in the form of diodes, TVS & fuse, added inductors for EMI filtering (two of which I am seeking input on to see if they make sense for the intended purposes), added decoupling, bulk, bypass and wiper caps, an LED for power indication, potentiometers for LED brightness and, more importantly, in the case of R4, for tuning the resonant frequency by varying the amount of resistance at the transistors' bases...As to R4, it connects from the collector to the transistor bases along with the wiper capacitor C7. It controls how much signal gets fed back from the output side to the input side (base).The choices appear sound to me but that's why I'm asking for input. Which particular portion(s) of the schematic strike you as non-functional or problematic and why?Quote from: Paul Price on May 25, 2025, 04:58:48 pm

author: lobster
author_rank: Contributor
timestamp: May 25, 2025, 05:38:00 pm
content: As to the LED pot, I want to vary the brightness and I have a ton of extra pots on hand.The reason I added D2 was because the barrel jack (via D1) can feed power into V_SYS, but so can the USB-C. Without D2, if the barrel jack is plugged in at 24V, it could push current back into the USB-C port,possibly damaging the USB-C circuitry.I am going to take a look at the oscillator question shortly. I am not in front of my primary desktop and I'd like to make sure I didn't goof up on it before replying.Quote from: Paul Price on May 25, 2025, 04:58:48 pm

author: Paul Price
author_rank: Super Contributor
timestamp: May 25, 2025, 05:53:15 pm
content: D1 and D2 are wired exactly the same way in your schematic.You are shorting B4 to B9 so it connects directly to D3 and so I feel that D3 connects to D1Your oscillator circuit is a smoke generator because the coil shorts out the power supply and I feel the emitter resistors are 10K and too high to do anything.

author: MariuszD
author_rank: Regular Contributor
timestamp: May 25, 2025, 06:16:28 pm
content: This circuit is not push-pull. Transistors are connected parallel to the coil. There is no feedback to make an oscillator. Q1 is inverted. Is this created by AI?Slayer exciter looks like this

author: lobster
author_rank: Contributor
timestamp: May 25, 2025, 06:50:41 pm
content: Paul, thanks for the specific concerns. Let me try to address these as I understand them (which may be totally mistaken on my part).I see it now! Yes, I can get rid of D1 and D2 and just keep D3. Alternatively, I could get rid of D3 and keep D1 and D2. Sorry it did notclickearlier. I will adjust the schematic accordingly. Thanks!As to the resistors, thank you!!! Thank you!!! I see that the 220 mOhm W22-0R22JI I wanted somehow ended up coming through as 10 kOhm W22-10KJI. This is an incredibly helpful catch on your part and I genuinely thank you for it! Now that I reevaluate it, I am inclined to go with 70 mOhms resistors for R5 and R7 as I calculate this will allow far more power to the transistors but not risk being anywhere near the ratings.As tothe coil shorting out the power supply, I still believe the design is sound. In my Slayer Exciter design, the primary coil isn’t directly shorting the supply. It’s part of a controlled oscillator circuit.The primary coil is center-tapped, and that center tap is connected to the main power rail through an inductor. The two ends of the coil connect to the collectors of two transistors. Their emitters go through low-value resistors—0.07 ohms—to ground. These resistors are there specifically to limit current and protect the transistors.Current can only flow when one of the transistors turns on. Even then, the coil’s inductance resists sudden changes in currentso it should not behave like a simple resistor. Inductors limit how fast current can rise, so they naturally prevent the coil from acting like a short circuit.The transistors are controlled by a feedback loop that causes them to switch on and off alternately—not simultaneously. That alternating switching causes current to pulse through each half of the coil, generating the magnetic field that drives the secondary. There’s never a point where the circuit creates a continuous, direct path from power to ground through the coil.Also, the emitter resistors serve as current limiters. If too much current tried to flow for any reason, the voltage drop across those resistors would increase, which limits the current and helps protect the circuit.So even though the coil might look like it’s bridging the power rail and ground, it’s actually part of a carefully timed, resonant switching system. Current is limited by the oscillator’s behavior, the coil’s inductance, and the emitter resistors. Because of that, the design doesn’t allow the coil to become a short circuit.Does this make sense?Quote from: Paul Price on May 25, 2025, 05:53:15 pm

author: lobster
author_rank: Contributor
timestamp: May 25, 2025, 06:55:41 pm
content: Thanks for raising these concerns, MariuszD. No, it's not created by AI, although I have used AI to clean up my BOM (which was a mistake as it altered some of the part numbers which caused a bit of a headache)...First, my design is a push-pull oscillator. The primary coil has a center tap that connects to the power supply. Each end of the coil connects to the collector of one transistor — Q1 and Q2. These transistors take turns switching on and off, driving current through each half of the coil in opposite directions.There is a feedback path; I’m using a winding on a toroidal core that’s magnetically linked to the coil. This winding sends a signal to the transistor bases through a potentiometer and capacitor. That signal controls the switching and keeps the circuit oscillating. So yes, it does have feedback.As for the claim that “Q1 is inverted,” I don't think that's right. Q1 is a PNP transistor, so its emitter connects to the positive rail, and the base is pulled down by the feedback to power up. Q2 is an NPN, and it's set up the opposite way — which is exactly what I want.If I'm not seeing something right here, please help me out. Thanks!Quote from: MariuszD on May 25, 2025, 06:16:28 pm

author: lobster
author_rank: Contributor
timestamp: May 25, 2025, 07:11:55 pm
content: Folks, I'm inclined to redraw the schematic to incorporate the current limiting resistor change, the elimination of D3, and (this is new) the swapping of the transistors to reflect a new complementary pair which are easier to source. They appear to be drop-in replacements for my application. I should have this redrawn within the next couple of days max. Any other thoughts in the meanwhile would be appreciated. Thanks!

author: tooki
author_rank: Super Contributor
timestamp: May 25, 2025, 07:28:45 pm
content: Quote from: SteveThackery on May 20, 2025, 10:24:07 amWhile thephysicsof electronics certainly only follow the rules, thehumanswho actually design circuits most certainly do have illogical, irrational preferences and methods that do influence their designs.We often have many viable alternative ways of solving a problem, and often there is no substantive advantage to one approach over another. In those cases, our personal preferences, biases, emotions, etc, will come into play and become the deciding factors. Heck, I’m sure they are sometimes in many cases where one or another approachdoeshave an advantage, but the human is unaware of said advantage at that moment.So IMHO anyrealisticinterpretation of the human design and engineering process will acknowledge that we humans very much do introduce illogical, irrational decisions into a design. (This is why human factors is such an important field of study, applicable to practically every domain: what humansshoulddo, what wethinkwe should do, and what weactuallydo are quite different things!)

author: tooki
author_rank: Super Contributor
timestamp: May 25, 2025, 07:55:01 pm
content: Quote from: lobster on May 23, 2025, 09:53:42 pmYou could combine D1 and D3; their cathodes are going to the same rail anyway.You should use a higher-value resistor and pot for the LED. If I’m understanding this correctly, it’s powered by a 20V rail. With the pot turned to minimum, you’d be perilously close to that LED’s 20mA absolute maximum (which remember, is NOT the “design maximum”). You should size the fixed resistor to protect the LED no matter what the pot is set to. (Since it’s a 3V LED, your voltage drop across the resistors is 17V, so an 1.8K resistor would give you just under 10mA, and 1.5K would give you just over 11mA.) Plus, while that particular LED is not a super-bright one, blue LEDs can appear very bright, so give yourself plenty of adjustment to dim it down. I’d probably use a 5K or 10K pot.

author: tooki
author_rank: Super Contributor
timestamp: May 25, 2025, 08:01:20 pm
content: Quote from: lobster on May 25, 2025, 05:38:00 pmAs drawn, D2 is backwards: it will allow power from the barrel jack to feed to the USB power.

author: tooki
author_rank: Super Contributor
timestamp: May 25, 2025, 08:34:03 pm
content: Quote from: lobster on May 25, 2025, 06:50:41 pmBut you don’t have an oscillator.First of all, youareshorting the coil directly from Vsys to ground. The transistors aren’t in its circuit at all!Second, your transistors don’t have any path for current to get to their bases, they are floating. So they cannot do anything.Third, even if they did, that’d be a bad thing, because with just 70mOhm emitter resistors, you’d have 285 amps flowing through them! I didn’t check, but I doubt your transistors can handle that (even if your supply could).This circuit seems cobbled together without the faintest understanding of how circuits work.The rest of the response feels more and more like an AI text, justifying itself while in blatant contradiction of the actual output (the schematic).Quote from: lobster on May 25, 2025, 06:50:41 pmNo it isn’t. As drawn, you have a single-winding, untapped coil in parallel with the inductor, and both are connected directly to the ground and Vsys rails since you’re shorting out SW2.Quote from: lobster on May 25, 2025, 06:50:41 pmNot in your schematic they don’t. Both collectors connect directly to Vsys.Quote from: lobster on May 25, 2025, 06:50:41 pm70mOhms is essentially a dead short. It won’t limit current in any meaningful way. Again: about 285 amps.Quote from: lobster on May 25, 2025, 06:50:41 pmThe transistors aren’t in the inductor/coil circuit at all. Yes, inductance limits how fast current can rise, but not how far. Since the voltage never gets switched, the current will rise up to that of a dead short, limited only by the DC resistance of the coil.Quote from: lobster on May 25, 2025, 06:50:41 pmThe transistors are not controlled at all.Quote from: lobster on May 25, 2025, 06:50:41 pmThat is actually the only state this circuit has.Quote from: lobster on May 25, 2025, 06:50:41 pmAgain, nonsense.Quote from: lobster on May 25, 2025, 06:50:41 pmNonsense. There is no switching system at all, since the transistors are completely bypassed.Quote from: lobster on May 25, 2025, 06:50:41 pmNo.

author: lobster
author_rank: Contributor
timestamp: May 25, 2025, 10:35:07 pm
content: To those who replied today with specific concerns and/or suggestions, thank you. I am going to rework this thing as it is clear I have goofed pretty substantially at my first attempt. I haven't taken an electrical engineering class since the 90s and it's apparent I've forgotten much of it. Please allow me a bit of time to fix this schematic up and come back to the forum after I do some substantial rework. Thanks for your patience.

author: Analog Kid
author_rank: Super Contributor
timestamp: May 25, 2025, 10:52:25 pm
content: OK, sounds good.Request:Ditch whatever method you're using to create those schematics. Or change the way you're using that tool.Don't give us disembodied parts/pieces that we mentally have to connect connector "A" to its mate ... somewhere else in that mess.Your circuit is simple enough that you can just draw the whole enchilada at once, no connectors needed.Much easier to follow that way. (For you, too.)Also, no need to label a capacitor as a "CAP", resistor as a "RES", etc.OK, we expect great things of you now ...

author: lobster
author_rank: Contributor
timestamp: May 25, 2025, 11:22:59 pm
content: Thanks, amigo. I expect passably acceptable things from myself given my first effort was not up to par. I tried to follow the earlier advice of labeling everything such that it takes as little time as possible to figure out what's what. You're right. I should be able to show the entire plan in a single combined image given the moderate number of components. I think you are spot on in that I was confusing myself by having the separate portions partitioned from one another when this was put together. Please bear with me a bit while I rework this sucker.Quote from: Analog Kid on May 25, 2025, 10:52:25 pm

author: lobster
author_rank: Contributor
timestamp: June 03, 2025, 12:09:21 am
content: I spent time on this to try to fix it up and address the concerns raised here. USB-C power is limited to 3A due to IC. *Fingers crossed* Here goes nothing...Quote from: Analog Kid on May 25, 2025, 10:52:25 pmHere's the updated BOM and the schematic is attached:Item Quantity Designator Manufacturer_Name Manufacturer_Part_Number Description1 2 C1, C2 EPCOS - TDK Electronics B32526R0107K000 CAP FILM 100UF 10% 63VDC RADIAL2 3 C3, C8, C11 Panasonic ECW-FD2J104J4 CAP FILM 0.1UF 5% 630VDC RADIAL3 4 C4, C7, C12, C13 TDK Corporation CGA5L4NP02J103G160AA 10000 pF ±20% 630V Ceramic Capacitor C0G, NP0 1206 (3216 Metric)4 1 C5 Samsung Electro-Mechanics CL32E106KBVVPOE Multilayer Ceramic Capacitors MLCC - SMD/SMT 10uF X8L 50V 1210 Auto grade5 3 C6, C9, C10 TDK C3216X7R1H105K160AE CAP CER 1UF 50V X7R 12066 2 D1, D2 Rohm Semiconductor RB088T-30HZC9 Diode Array 1 Pair Common Cathode 30 V 5A Through Hole TO-220-3 Full Pack7 4 D3, D4, D7, D8 onsemi FDLL3595 DIODE STANDARD 125V 200MA SOD808 2 D5, D6 Diotec Semiconductor 3EZ62 DIODE ZENER 62V 3W DO204AC9 1 F1 Littelfuse Inc. 0618005.MXP FUSE GLASS 5A 250VAC 5X20MM10 4 HS1, HS2, HS3, HS4 Wakefield Thermal OMNI-UNI-34-50 HEATSINK TO-247 TO-264 TO-22011 1 J1 Switchcraft Inc. L721RAHLP LOW PROFILE RAPC MOUNT DC POWER12 2 J2, J3 Molex 47053-3000 Connector Header Through Hole 4 position 0.100" (2.54mm)13 2 J5, J6 Phoenix Contact 1714971 2 Position Wire to Board Terminal Block Horizontal with Board 0.375" (9.53mm) Through Hole14 3 L1, L2, L3 Bel Signal HTTI-47-5.6 47 µH Shielded Toroidal Inductor 5.6 A 36mOhm Max Vertical, No Base, 2 PC Pin15 1 LED1 ams OSRAM KB DELPS2.12-QHRI-24-Z555-10-S Blue 466nm LED Indication - Discrete 2.95V 2-SMD, Flat Leads16 1 Q1 onsemi 2SA2210-1E TRANS PNP 50V 20A TO-220F-3SG17 1 Q2 onsemi 2SC6082-1E TRANS NPN 50V 15A TO-220F-3SG18 1 R1 Bourns PCW1D-B16-KAB103L Potentiometers 10K 20% Sq 22mm Single Turn19 1 R2 Rohm Semiconductor SDR03EZPJ222 RES SMD 2.2 KOHM 5% 0.3W 060320 2 R3, R6 Bourns Inc. CR2512-FX-1001ELF RES SMD 1K OHM 1% 1W 251221 2 R4, R11 Bourns PCW1J-R24-KAB252L POT 2.5K OHM 3/4W PLASTIC LINEAR22 2 R5, R7 IRC / TT Electronics W22R120JRLF Wirewound Resistors - Through Hole 0.12ohm 7watt 5%23 2 R8, R12 KOA Speer Electronics, Inc. RK73H1JTTD1002F RES 10K OHM 1% 1/10W 060324 2 R9, R10 KOA Speer Electronics, Inc. RN73H2ATTD1002A05 RES 10K OHM 0.05% 1/8W 080525 1 R13 Vishay TNPW12061M00BYEA RES 1M OHM 0.1% 0.52W 120626 1 R14 Vishay Sfernice P2TC2010D1001LNTA P2TC2010 2PPM/C 1K 0,01% N TA27 3 SW1, SW2, SW3 NKK MN11SS1W03 Single-Pole, Single-Throw Switch28 11 TP1, TP2, TP3, TP4, TP5, TP6, TP7, TP8, TP9, TP10, TP11 Keystone Electronics 5198TR PC TEST POINT MINIATURE GRAY29 3 TVS1, TVS2, TVS3 Texas Instruments TVS2701DRBR 27-V bidirectional flat-clamp surge protection device30 1 U1 STMicroelectronics STUSB4500QTR USB Controller USB 2.0 I2C Interface 24-QFN (4x4)31 1 USB_CONN Amphenol ICC (Commercial Products) 124019282112A USB TYPE C, RECEPTACLE, TOP MOUN32 1 F2 Littelfuse Inc. 06183.15MXP FUSE GLASS 3.15A 250VAC 5X20MM33 2 Schurter 31.8275 Fuse Holder OGN-SMD Fuseholder 5x20

author: Analog Kid
author_rank: Super Contributor
timestamp: June 03, 2025, 01:19:20 am
content: Quote from: lobster on June 03, 2025, 12:09:21 amNo it's not. Didja forget it?

author: lobster
author_rank: Contributor
timestamp: June 03, 2025, 02:00:44 am
content: Apparently so, though I should claim it was to build anticipation like a drumbeat. Let's try this again.Quote from: Analog Kid on June 03, 2025, 01:19:20 am

author: Analog Kid
author_rank: Super Contributor
timestamp: June 03, 2025, 02:18:19 am
content: Now your schematic image is waaaaaay too big (13,200 x 10,200???).Please make it a bit smaller so we can see the whole thing but zoom in for some detail.

author: lobster
author_rank: Contributor
timestamp: June 03, 2025, 02:21:20 am
content: Here it is at 1/4 the prior resolution. Let me know if this works, please.Quote from: Analog Kid on June 03, 2025, 02:18:19 am

author: Analog Kid
author_rank: Super Contributor
timestamp: June 03, 2025, 02:25:02 am
content: Much better.

author: lobster
author_rank: Contributor
timestamp: June 03, 2025, 02:33:03 am
content: While I am fairly confident you mean the graphic, I'm hopeful its contents are also much better.Quote from: Analog Kid on June 03, 2025, 02:25:02 am

author: lobster
author_rank: Contributor
timestamp: June 03, 2025, 02:47:47 am
content: What do you guys think about replacing R3 and R6 with 1 watt, 1.65K ohm resistors? I want to ensure I don't break my 3A total circuit envelope and I don't want to run close to it. These would be increased from the 1K ohm resistors currently shown in the graphics I recently uploaded.

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: June 03, 2025, 05:22:39 am
content: How is this circuit supposed to work if the PNP emitter is connected to 0V, and the PNP collector is connected to Vcc?Why are you bypassing the base of each transistor with diodes?Why is the secondary coil basically shorted out? (I'm assuming that's the 47uH).

author: MariuszD
author_rank: Regular Contributor
timestamp: June 03, 2025, 06:54:37 am
content: Can you give a reason why you connected the circled components like this?Each one is incorrectly connected or has a bad value or does not perform any significant function.In electronics, everything must make sense. There must be a logical reason for using each component.Human with insufficient knowledge may make mistakes, but he cannot create complete nonsense. There are no limits to the level of nonsense that AI can create. Humans have limits. That's why I know this is the work of AI. For now, AI is unable to create a working circuit, you have to learn on your own.First step of learning electronics is to learn how components work. The second step is to understand how simple correct schematics work. Next it is to modify it. Creating from scratch is for advanced practitioners.My advice for you take simple CCFL inverter and try to understand it, read about it, learn how it works, learn how to chose components. Build such a circuit, connect the oscilloscope, do a simulation. You can add some components when you know something is working suboptimally and you have an idea how to improve it.

author: MariuszD
author_rank: Regular Contributor
timestamp: June 03, 2025, 07:29:17 am
content: Another great circuit for you is Mazzilli's flyback driver. Build it, make some sparks, measure it, modify it. Have fun. Be careful with high voltages. Don't waste your time for AI.Circuits like this make huge RFI. Big spark is like EMP. You can brick other devices by that. Make it simple, no USB, no other connections, no long wires nearby. Use simple and cheap power supply. Many SMPS's cannot work properly with this level RFI. They can break or turn off. Keep other electronic devices far away from your high voltages/arcs.

author: Analog Kid
author_rank: Super Contributor
timestamp: June 03, 2025, 09:39:11 am
content: How many turns on the secondary?

author: SteveThackery
author_rank: Super Contributor
timestamp: June 03, 2025, 10:02:14 am
content: Quote from: lobster on June 03, 2025, 02:21:20 amWow, that lookscomplicated. But you designed it, so could you be kind enough to walk us through the circuit, explaining how it works?

author: lobster
author_rank: Contributor
timestamp: June 03, 2025, 12:51:15 pm
content: Addressing the questions in reverse order, the 47uH is not the secondary. The secondary connects to the terminal block where mentioned in red on the schematic. The diodes are intended to limit reverse voltage across base-emitter. I need to check on the PNP connections as you're right; polarity looks reversed.Quote from: EggertEnjoyer123 on June 03, 2025, 05:22:39 am

author: lobster
author_rank: Contributor
timestamp: June 03, 2025, 12:53:22 pm
content: Roughly 1100.Quote from: Analog Kid on June 03, 2025, 09:39:11 am

author: lobster
author_rank: Contributor
timestamp: June 03, 2025, 01:00:12 pm
content: Thank you for replying. While I appreciate your ongoing conviction in that AI designed the circuit, as was mentioned before, AI was used to assist with formatting my BOM, not designing the circuit. While I am happy to address the function of any particular component, you circled a substantial number of components and it is unclear whether your concern with any individual component is its intended function or its rated value. If you would please advise which concern applies to which circled component, I can reply accordingly. It is entirely possible I may have goofed on a value but it is far less likely components were included without any intended function just for giggles. I'm far from perfect but everything was added for a specific reason.Quote from: MariuszD on June 03, 2025, 06:54:37 am

author: lobster
author_rank: Contributor
timestamp: June 03, 2025, 01:15:53 pm
content: Yes, most definitely. I spent a ton of time reworking the schematic based upon the concerns raised here. Power can be applied via either 20V USB-C (subject to a 3.15A slow blow fuse given the IC is rated to a max of 3A) or 24V barrel conector (5A slow blow fused). Schottky diodes protect both inputs and prevent the barrel connector from backflowing to USB. There are test points wired to the USB-C IC to allow for programming the IC to negotiate 20V instead of the default 5V. A switch cuts power to the circuit at the far end of the power supply portion (toward the top center of the schematic).For the LED section, a set value resistor as well as a potentiometer have been added to limit voltage to the LED and allow for brightness adjustment. There is a wiper cap there, too, to smooth adjustment.There are two 4-pin fan headers which have a toggle switch (same part number as other switches) to power on/off. I may not use these but they are intended to allow for one fan to cool the TO-220 package transistors and another to cool the TO-220 package diodes.A switch controls power to the transistor / oscillating circuitry (where I have been struggling). This section can be powered on regardless of whether the fan headers have power. Neither is reliant upon the other being in a particular power state in order to function. My intention was to have one transistor power on as the other powers off and vice versa. Resistors were added to limit current to the transistors to stay within a 3A total circuit power envelope. Beyond the set value resistors, potentiometers (lower resistance than the one used with the LED but same style) allow increasing resistance to each of the transistors individually to aid in tuning.Throughout the circuit, a number of diodes, capacitors, and inductors have been added for a variety of reasons, ranging from smoothing power to decoupling to protecting the IC from transients.I can address any of the specific components to advise why they were added where they were added if you wish.Quote from: SteveThackery on June 03, 2025, 10:02:14 am

author: lobster
author_rank: Contributor
timestamp: June 04, 2025, 01:01:12 am
content: I fixed the connections to Q1. Thanks, EggertEnjoyer123, for picking up on the base and emitter being flipped for Q1 in the prior revision. Please see the updated schematic and latest BOM attached. I am truly hoping I am on the right path here.Item Quantity Designator Manufacturer_Name Manufacturer_Part_Number Description Footprint1 2 C1, C2 EPCOS - TDK Electronics B32526R0107K000 CAP FILM 100UF 10% 63VDC RADIAL CAP_B32526R0107K0002 3 C3, C8, C11 Panasonic ECW-FD2J104J4 CAP FILM 0.1UF 5% 630VDC RADIAL ECW-FD2J104J3 4 C4, C7, C12, C13 TDK Corporation CGA5L4NP02J103G160AA 10000 pF ±20% 630V Ceramic Capacitor C0G, NP0 1206 (3216 Metric) C12064 1 C5 Samsung Electro-Mechanics CL32E106KBVVPOE Multilayer Ceramic Capacitors MLCC - SMD/SMT 10uF X8L 50V 1210 Auto grade C12105 3 C6, C9, C10 TDK C3216X7R1H105K160AE CAP CER 1UF 50V X7R 1206 C12066 2 D1, D2 Rohm Semiconductor RB088T-30HZC9 Diode Array 1 Pair Common Cathode 30 V 5A Through Hole TO-220-3 Full Pack TO-220-37 4 D3, D4, D7, D8 onsemi FDLL3595 DIODE STANDARD 125V 200MA SOD80 SOD-808 2 D5, D6 Diotec Semiconductor 3EZ62 DIODE ZENER 62V 3W DO204AC DO-204AC (DO-15)9 1 F1 Littelfuse Inc. 0618005.MXP FUSE GLASS 5A 250VAC 5X20MM 0618005.MXP10 4 HS1, HS2, HS3, HS4 Wakefield Thermal OMNI-UNI-34-50 HEATSINK TO-247 TO-264 TO-220 OMNI-UNI-34-5011 1 J1 Switchcraft Inc. L721RAHLP LOW PROFILE RAPC MOUNT DC POWER L721RAHLP12 2 J2, J3 Molex 47053-3000 Connector Header Through Hole 4 position 0.100" (2.54mm) 47053-300013 2 J5, J6 Phoenix Contact 1714971 2 Position Wire to Board Terminal Block Horizontal with Board 0.375" (9.53mm) Through Hole PHOENIX_171497114 3 L1, L2, L3 Bel Signal HTTI-47-5.6 47 µH Shielded Toroidal Inductor 5.6 A 36mOhm Max Vertical, No Base, 2 PC Pin IND_HTTI-47-5.615 1 LED1 ams OSRAM KB DELPS2.12-QHRI-24-Z555-10-S Blue 466nm LED Indication - Discrete 2.95V 2-SMD, Flat Leads LED_SMD16 1 Q1 onsemi 2SA2210-1E TRANS PNP 50V 20A TO-220F-3SG TO-220-3-PNP17 1 Q2 onsemi 2SC6082-1E TRANS NPN 50V 15A TO-220F-3SG TO-220-3-NPN18 1 R1 Bourns PCW1D-B16-KAB103L Potentiometers 10K 20% Sq 22mm Single Turn Res_Pot19 1 R2 Rohm Semiconductor SDR03EZPJ222 RES SMD 2.2 KOHM 5% 0.3W 0603 R060320 2 R3, R6 KOA Speer Electronics, Inc. RK73H3ATTE1651F Thick Film Resistors - SMD 1.65K OHM 1% R251221 2 R4, R11 Bourns PCW1J-R24-KAB252L POT 2.5K OHM 3/4W PLASTIC LINEAR Res_Pot22 2 R5, R7 IRC / TT Electronics W22R120JRLF Wirewound Resistors - Through Hole 0.12ohm 7watt 5% W22R120JRLF_axial_22mmx0.8mm23 2 R8, R12 KOA Speer Electronics, Inc. RK73H1JTTD1002F RES 10K OHM 1% 1/10W 0603 R060324 2 R9, R10 KOA Speer Electronics, Inc. RN73H2ATTD1002A05 RES 10K OHM 0.05% 1/8W 0805 R080525 1 R13 Vishay TNPW12061M00BYEA RES 1M OHM 0.1% 0.52W 1206 R120626 1 R14 Vishay Sfernice P2TC2010D1001LNTA P2TC2010 2PPM/C 1K 0,01% N TA R201027 3 SW1, SW2, SW3 NKK MN11SS1W03 Single-Pole, Single-Throw Switch SWITCH_MN11SS1W0328 11 TP1, TP2, TP3, TP4, TP5, TP6, TP7, TP8, TP9, TP10, TP11 Keystone Electronics 5198TR PC TEST POINT MINIATURE GRAY KEYSTONE_5198TR29 3 TVS1, TVS2, TVS3 Texas Instruments TVS2701DRBR 27-V bidirectional flat-clamp surge protection device VSON-830 1 U1 STMicroelectronics STUSB4500QTR USB Controller USB 2.0 I2C Interface 24-QFN (4x4) USB_C_IC_VFQFN-2431 1 USB_CONN Amphenol ICC (Commercial Products) 124019282112A USB TYPE C, RECEPTACLE, TOP MOUN USB_C_124019282112A32 1 F2 Littelfuse Inc. 06183.15MXP FUSE GLASS 3.15A 250VAC 5X20MM33 2 Schurter 31.8275 Fuse Holder OGN-SMD Fuseholder 5x20

author: SteveThackery
author_rank: Super Contributor
timestamp: June 04, 2025, 10:53:07 am
content: Why have you doubled up D3 and D4 with D7 and D8?Aren't D4 and D8 upside down?PS: Am I the only one who finds the schematic virtually impossible to follow?

author: MariuszD
author_rank: Regular Contributor
timestamp: June 04, 2025, 11:00:50 am
content: Quote from: lobster on June 03, 2025, 01:00:12 pmThis will flood your thread with many questions.Errors and nonsense in first half of the "oscillator"schematic:1- why diode is shunting BE? Why you want to divide the current? how you suppose to control this division (it is temperature dependent)2- why there are two diodes?3- why diode is shorting CE of the transistor. Transistor will never have a chance to cut of the current.4- capacitor 100nF parallel to 0,12Ohm can change impedance over 13MHz irrelevant for this circuit5- R13 parallel to R14 does nothing6- this filter cuts off over 100Hz. What is your expected oscillation frequency? Why you want to slow down the switching?7- why potentiometer wiper is connected to the signal source (backwards)8- why snubber is connected parallel to the resistor of the filter. Resistor in snubber has 6 times more resistance so it will do nothing9- another resistor that is in fact parallel to R14 and does nothing.There are more important errors like Q1 connected to V_sys. I suppose that you don't know what you are doing. In that case discussion about the details will be meaningless. I want you to draw simplified block diagram. Only most important connections, transistors, coils, power supplies. Example in the attachment.Quote from: lobster on June 03, 2025, 01:00:12 pmYou are fixating on non important things. Oscillator is most important. If oscillator doesn't work whole device doesn’t work.Have you seen need to adjust the brightness of the power on led?Have you seen such a circuit where regulation not being smooth?"smoothing" capacitor gives about 10us time constant. Is your eye 1000 times faster than average human eye? Are you a cyborg?QuoteHow do you calculated it? (it is wrong) In power oscillator resistor is not good limiter it will waste a lot of energy. Popular solution is small resistor with transistor or comparator connected to the power transistor. Don't do it now, do it when all circuit will be correct.QuoteThrow it away. When something is difficult, try easy way, keep only most important elements.If you are not using AI you are using similar method like throwing a dice.

author: lobster
author_rank: Contributor
timestamp: June 04, 2025, 12:18:16 pm
content: Steve, thanks for your reply.They were doubled up solely for redundancy. Is that crazy?Yes, D4 and D8 are upside down. That's 100% an error I will fix.Quote from: SteveThackery on June 04, 2025, 10:53:07 am

author: MariuszD
author_rank: Regular Contributor
timestamp: June 04, 2025, 01:21:25 pm
content: Quote from: lobster on June 04, 2025, 12:18:16 pmIn this place redundancy is unreasonable. Redundancy is expected to improve reliability. This diode is not conducting significant currents or voltages. It is not expected to fail on its own. Transistor is hundred times prone to failure. Why there is no redundancy there? Transistor fail making short circuit so parallel connection is useless.I have listed 9 errors of nonsense you answered two of them

author: lobster
author_rank: Contributor
timestamp: June 04, 2025, 01:44:32 pm
content: Marius,Based on multiple commenters mentioning the diode redundancy, I am going to go ahead and remove one for each transistor.I have not had a chance to spend time to go through your concerns yet. I don't want to shortchange you with an overly short reply. Please allow me a bit of time to go through these items (as I am doing so on breaks during the workday).Thanks!Quote from: MariuszD on June 04, 2025, 01:21:25 pm

author: MariuszD
author_rank: Regular Contributor
timestamp: June 04, 2025, 02:18:37 pm
content: Add to the list:10- where do this current expected to flow? from V_sys to V_sys?11 - why is base connected to V_sys?12 - in previous version Q1 base current will flow all the time so transistor is turned on all the time. Is it on purpose?13- how do you want to adjust R1 and R4? Two potentiometers for one winding. How do yo know that there is need for adjust R1?How do yo know that there is need for adjust R4 but not R1?

author: lobster
author_rank: Contributor
timestamp: June 04, 2025, 06:04:03 pm
content: Thank you! I am still going through and cleaning up the schematic based upon your prior comments. Please give me a little more time to consider all of your comments and observations. I really appreciate it!!!Quote from: MariuszD on June 04, 2025, 02:18:37 pm

author: UnijunctionTransistor
author_rank: Frequent Contributor
timestamp: June 04, 2025, 06:35:38 pm
content: Quote from: lobster on May 19, 2025, 09:49:45 pmI will go easy on you. Easy, respectfullybut also firmly,I would suggest for you to assemble the proven original Slayer circuit first, and fully understand why and how it operates. If you can't build it, at the very least simulate it with LTSpice. Most and foremost, understand the feedback mechanism which makes it to oscillate.Once you have understood its operation, then and only then attempt something more complicated. Right now, it seems that you are only throwing components haphazardly into a schematic, without much thought or knowledge. All of your posted circuits so far, have fatal flaws in the power section, which appears you fail to grasp. Those have been addressed earlier and will not repeat them here.

author: lobster
author_rank: Contributor
timestamp: June 04, 2025, 07:37:56 pm
content: Marius,Thank you so much for your detailed feedback and comments. I really appreciate it as it helps me understand where to focus my efforts.I made a slew of changes thanks to your feedback...1- why diode is shunting BE? Why you want to divide the current? how you suppose to control this division (it is temperature dependent)I had originally included them to protect from reverse voltage spikes. From your question and other Slayer designs, it appears this is not necessary to include. I'm going to remove them altogether.2- why there are two diodes?Addressed in prior reply. I removed one as this was thought to add redundancy. As mentioned in 1, above, I'm just going to remove them altogether.3- why diode is shorting CE of the transistor. Transistor will never have a chance to cut of the current.It shouldn't be but it is. I need to remove it as it was an error to have included it. I am removing both D5 and D6.4- capacitor 100nF parallel to 0,12Ohm can change impedance over 13MHz irrelevant for this circuitSpot on. I am removing it. It doesn't seem likely to help.5- R13 parallel to R14 does nothingR14 has been removed. Thanks!6- this filter cuts off over 100Hz. What is your expected oscillation frequency? Why you want to slow down the switching?Was ballparking around 250 kHz. I am going to remove C10. Good catch as it is totally counterproductive. I am also removing C6 for the same reason.7- why potentiometer wiper is connected to the signal source (backwards)I flipped pins 1 and 3 for both R4 and R11. This will make its use more logical.8- why snubber is connected parallel to the resistor of the filter. Resistor in snubber has 6 times more resistance so it will do nothingI removed both C13 and R12.9- another resistor that is in fact parallel to R14 and does nothing.I removed this pull-up resistor.To recap, the following have been removed (original component designators as shown in prior posts):D3, D4, D5, D6, D7, D8, R9, R10, R12, R14, C6, C7, C8, C10, C11, C12, C13Add to the list:10- where do this current expected to flow? from V_sys to V_sys?In short, no. Of course not. I am not sure I am understanding what you are asking in this one. Please advise if this concern applies to the current schematic I'm attaching here and, if so, please give me a bit more info as I may be missing something obvious on this one.11 - why is base connected to V_sys?This is a massive error on my part. It looks like I somehow flipped the orientation of the transistor. I’m putting it back as it should be here.12 - in previous version Q1 base current will flow all the time so transistor is turned on all the time. Is it on purpose?No, not intentional. This should be fixed by recent revision.13- how do you want to adjust R1 and R4? Two potentiometers for one winding. How do yo know that there is need for adjust R1?What was R1, I believe, was a 10K pot solely for the LED. The 2.5K pots were for each transistor.How do yo know that there is need for adjust R4 but not R1?In the schematic I am adding to this post, R5 and R6 are the pots tied to base of each of the transistors.Updated BOM:Item Quantity Designator Manufacturer_Name Manufacturer_Part_Number Description Footprint1 2 C1, C2 EPCOS - TDK Electronics B32526R0107K000 CAP FILM 100UF 10% 63VDC RADIAL CAP_B32526R0107K0002 1 C3 Panasonic ECW-FD2J104J4 CAP FILM 0.1UF 5% 630VDC RADIAL ECW-FD2J104J3 1 C4 TDK Corporation CGA5L4NP02J103G160AA 10000 pF ±20% 630V Ceramic Capacitor C0G, NP0 1206 (3216 Metric) C12064 1 C5 Samsung Electro-Mechanics CL32E106KBVVPOE Multilayer Ceramic Capacitors MLCC - SMD/SMT 10uF X8L 50V 1210 Auto grade C12105 1 C6 TDK C3216X7R1H105K160AE CAP CER 1UF 50V X7R 1206 C12066 2 D1, D2 Rohm Semiconductor RB088T-30HZC9 Diode Array 1 Pair Common Cathode 30 V 5A Through Hole TO-220-3 Full Pack TO-220-37 1 F1 Littelfuse Inc. 0618005.MXP FUSE GLASS 5A 250VAC 5X20MM 0618005.MXP8 1 F2 Littelfuse Inc. 06183.15MXP FUSE GLASS 3.15A 250VAC 5X20MM9 4 HS1, HS2, HS3, HS4 Wakefield Thermal OMNI-UNI-34-50 HEATSINK TO-247 TO-264 TO-220 OMNI-UNI-34-5010 4 Not on schematic Wakefield Thermal OMNI-220C UNIVERSAL TO-220 HEATSINK CLIP11 1 J1 Switchcraft Inc. L721RAHLP LOW PROFILE RAPC MOUNT DC POWER L721RAHLP12 2 J2, J3 Molex 47053-3000 Connector Header Through Hole 4 position 0.100" (2.54mm) 47053-300013 2 J4, J5 Phoenix Contact 1714971 2 Position Wire to Board Terminal Block Horizontal with Board 0.375" (9.53mm) Through Hole PHOENIX_171497114 3 L1, L2, L3 Bel Signal HTTI-47-5.6 47 µH Shielded Toroidal Inductor 5.6 A 36mOhm Max Vertical, No Base, 2 PC Pin IND_HTTI-47-5.615 1 LED1 ams OSRAM KB DELPS2.12-QHRI-24-Z555-10-S Blue 466nm LED Indication - Discrete 2.95V 2-SMD, Flat Leads LED_SMD16 2 Not on schematic Schurter 31.8275 Fuse Holder OGN-SMD Fuseholder 5x2017 1 Q1 onsemi 2SA2210-1E TRANS PNP 50V 20A TO-220F-3SG TO-220-3-PNP18 1 Q2 onsemi 2SC6082-1E TRANS NPN 50V 15A TO-220F-3SG TO-220-3-NPN19 1 R1 Bourns PCW1D-B16-KAB103L Potentiometers 10K 20% Sq 22mm Single Turn Res_Pot20 1 R2 Rohm Semiconductor SDR03EZPJ222 RES SMD 2.2 KOHM 5% 0.3W 0603 R060321 2 R3, R4 KOA Speer Electronics, Inc. RK73H3ATTE1651F Thick Film Resistors - SMD 1.65K OHM 1% R251222 2 R5, R6 Bourns PCW1J-R24-KAB252L POT 2.5K OHM 3/4W PLASTIC LINEAR Res_Pot23 2 R7, R8 IRC / TT Electronics W22R120JRLF Wirewound Resistors - Through Hole 0.12ohm 7watt 5% W22R120JRLF_axial_22mmx0.8mm24 3 SW1, SW2, SW3 NKK MN11SS1W03 Single-Pole, Single-Throw Switch SWITCH_MN11SS1W0325 11 TP1, TP2, TP3, TP4, TP5, TP6, TP7, TP8, TP9, TP10, TP11 Keystone Electronics 5198TR PC TEST POINT MINIATURE GRAY KEYSTONE_5198TR26 3 TVS1, TVS2, TVS3 Texas Instruments TVS2701DRBR 27-V bidirectional flat-clamp surge protection device VSON-827 1 U1 STMicroelectronics STUSB4500QTR USB Controller USB 2.0 I2C Interface 24-QFN (4x4) USB_C_IC_VFQFN-2428 1 USB_CONN Amphenol ICC (Commercial Products) 124019282112A USB TYPE C, RECEPTACLE, TOP MOUN USB_C_124019282112AQuote from: MariuszD on June 04, 2025, 02:18:37 pm

author: lobster
author_rank: Contributor
timestamp: June 04, 2025, 07:39:59 pm
content: Thanks for your feedback. When you refer to the power section, are you talking about the Power Supply section at the top left of the schematic or, more generally, V_SYS?Quote from: UnijunctionTransistor on June 04, 2025, 06:35:38 pm

author: Analog Kid
author_rank: Super Contributor
timestamp: June 04, 2025, 09:21:33 pm
content: Another minor point here:You seem quite enamored of making complete BOM lists, very specific with mfgr's part #s. Why?This is putting the cart waaaaay before the horse.Generally you want to come up with a working circuitfirst, at least in simulation, better yet a working prototype.After the inevitable tweaking, substitution andf ripping out and revising whole sections, that's the time to start putting together a BOM. Not at this point where it seems you don't even really understand how the damn thing's supposed to work.

author: lobster
author_rank: Contributor
timestamp: June 04, 2025, 09:51:38 pm
content: Simply want to head off potential questions and make it easier for whoever is reviewing the schematic to see what I have in mind.Quote from: Analog Kid on June 04, 2025, 09:21:33 pm

author: Analog Kid
author_rank: Super Contributor
timestamp: June 04, 2025, 10:03:07 pm
content: Quote from: lobster on June 04, 2025, 09:51:38 pmHaving all those specific mfgr. part #s is not gonna help.A reasonable schematic will.

author: SteveThackery
author_rank: Super Contributor
timestamp: June 04, 2025, 10:28:26 pm
content: Why are D1 and D2 zeners?R4 and R6 don't seem to do anything - they are bypassed by the other wire going to the transistor.

author: SteveThackery
author_rank: Super Contributor
timestamp: June 04, 2025, 10:48:49 pm
content: Dear Mr lobster,Respectfully and with kindness: you need to stop.You are trying to "design" a circuit without having any idea of what you are doing. Indeed, without any idea of what the circuit is supposed to do. Nor have you any idea of how to draw a schematic. You seem to seriously underestimate the discipline of electronic engineering: it is emphaticallynotanything like the "chuck some components at it and hope" approach you are using.You're supposed to understand the underlying theory before designing a circuit. Otherwise, how can you know how to design something if you don't know how it actually works?Are you trying to bolt something together from bits and bobs you've found online? Because it certainly doesn't look like a coherent design to me.I urge you to give up on thisdesignmess. Throw it away and consider the tried and tested alternatives you've been given earlier in the thread. You aren't ready to roll your own, trust me.

author: lobster
author_rank: Contributor
timestamp: June 04, 2025, 11:29:11 pm
content: I don't doubt that at all. However, I worry if I don't list a BOM, someone will object because they want to see a BOM.Quote from: Analog Kid on June 04, 2025, 10:03:07 pm

author: lobster
author_rank: Contributor
timestamp: June 04, 2025, 11:39:11 pm
content: D1 and D2 are not Zeners. They are Schottky.Is it the connection between Q2 base and SEC_COIL_OUT_N that you are saying is bypassing R4 and R6?Quote from: SteveThackery on June 04, 2025, 10:28:26 pm

author: lobster
author_rank: Contributor
timestamp: June 04, 2025, 11:45:35 pm
content: Steve,I appreciate your candor. That said, I am not quite ready to throw in the towel just yet. Without an idea of what's wrong, I'll be hard pressed to figure out what's right. I am on this forum specifically because I understand that there are complexities beyond my present understanding. I don't pretend to be an electrical engineer. I have been looking for constructive criticism, suggestions, etc. There has been quite a bit of it and much of it makes sense and is helpful. That said, if the thread or my efforts frustrate you, by all means, you're under no obligation to assist or participate. Perhaps you had a bad experience with a lobster but please remember I'm not that lobster. Each of us lobsters are distinct individuals with unique tastes and flavors. I have yet to claw anyone in this thread.Lastly, please note there are female lobsters. Not all lobsters are men. Not all lobsters interested in electronics are men.Truly,LobsterQuote from: SteveThackery on June 04, 2025, 10:48:49 pm

author: Analog Kid
author_rank: Super Contributor
timestamp: June 05, 2025, 12:03:29 am
content: Quote from: lobster on June 04, 2025, 11:29:11 pmNo they won't.Nobody's going to give a shit about there being no BOM for a meshugah, non-working circuit.

author: lobster
author_rank: Contributor
timestamp: June 05, 2025, 12:15:03 am
content: Okay, but if anyone does, I'm sending them your way, amigo.No more BOMs for the time being.Quote from: Analog Kid on June 05, 2025, 12:03:29 am

author: Analog Kid
author_rank: Super Contributor
timestamp: June 05, 2025, 12:32:19 am
content: BTW, if youse is from Boston or the East Coast, shouldn't that be "lobstah"?

author: lobster
author_rank: Contributor
timestamp: June 05, 2025, 12:36:50 am
content: I'll have you know that the cah is not fah from the bah. That is definitely not an entire Eastern Seaboard thing. It's very much a New England thing. I haven't even visited there in perhaps five years.Quote from: Analog Kid on June 05, 2025, 12:32:19 am

author: UnijunctionTransistor
author_rank: Frequent Contributor
timestamp: June 05, 2025, 01:24:41 am
content: The power section: what I meant is the oscillator circuit which provides the actual power to the output.

author: MariuszD
author_rank: Regular Contributor
timestamp: June 05, 2025, 07:19:59 am
content: 13- current can't flow between v_sys and v_sys14- you decided to make short circuit around the potentiometer. Potentiometer does nothing15- 1MOhm parallel to several kiloohms does nothingYou did something with things that I mentioned but I don't see any thinking behind it. You can't fix it because you don't know how it is expected to work.Take proven circuit and build it. It is hard enough for a newbie. It is expected that proven circuit will not work when assembled by a newbie. There will be some errors to find and fix. It is easier to find errors when you can compare to the working example.

author: SteveThackery
author_rank: Super Contributor
timestamp: June 05, 2025, 11:07:30 am
content: Quote from: lobster on June 04, 2025, 11:45:35 pmLobsters are the closest thing to an alien lifeform I've ever seen (apart from the octopus, of course). 😄Trust me, my comments are not fuelled by frustration in any way. They are fuelled by your responses to people's suggestions, and your overall approach to the job. I truly don't want to discourage you. I want to help get you on the right track. Right now you are on the wrong track.This is what the wrong track looks like:You are trying to run before you can walk. You are trying to design something without sufficient understanding of the basic principles underlyinghowit works. But most important of all, your idea of the design process does not reflect how design is actually done.Your approach to design seems to involve throwing together a circuit with no understanding of how circuits work, asking for assistance ("how do I make this work?"), throwing a load more components into the mix in response to the answers (again, without really understanding why), asking for more assistance, removing a load of components, asking for more assistance, rinse and repeat, until you eventually home in on something that ought to work.This is what therighttrack looks like:Proper design is a careful, logical process based upon a good understanding of the basic principles. It's like building a machine: everything must fit, everything must have a purpose. As the designer works through the design process it is quite common to simulate sub-sections of the circuit and to build prototypes to test for correct functionality. It is not unusual to break the design into functional modules which are gradually integrated into the whole as the design proceeds. It is also the case that a good designer will look for reference designs which might move them along (on the basis that reinventing the wheel is not good engineering).Your approach is nothing like that. And it shows: even your current effort has basic, fundamental mistakes which prove that you just don't understand what you have drawn.I think the most important thing for you now is to take a breath, put what you have done to one side, and start again. I suggest you write down exactly what you want your device to do. Think in terms of inputs and outputs, what should happen when. Then, I would probably start a new thread, and instead of asking "This is my circuit, what should I do to make it work?" I would ask:"I need a circuit which fulfils the following requirements. How should I go about the design process?"And then describe in detail what you want your circuit to do. Put forward your thoughts on how you might break the circuit into testable sub-sections. Point out similar circuits and reference designs that you have discovered and think might be helpful.I think if you took that approach people would be much more able to help you.Anyway, this is just what I think. Obviously it's up to you. But maybe think about it, at least?I've been doing some background reading on you. Apparently you can taste with your legs and hear with your body - that's cool! Ears are so last week. But the best bit is that you can regrow missing limbs. I must say, though, that I would find the regular moulting a real drag. 😉

author: SteveThackery
author_rank: Super Contributor
timestamp: June 05, 2025, 11:14:24 am
content: Quote from: lobster on June 04, 2025, 11:39:11 pmYes.

author: SteveThackery
author_rank: Super Contributor
timestamp: June 05, 2025, 11:43:15 am
content: Quote from: lobster on June 04, 2025, 07:37:56 pmAs an ex-reliability engineer I am genuinely impressed by your instinct to build resilience and redundancy into your circuit. You put two diodes in parallel to provide redundancy: if one fails, the other will continue to provide protection to the transistor.Forgive me, but this, though, is another example of you designing without understanding. Before considering redundancy you should perform a failure modes and effects analysis (FMEA). This will then inform your choice of how to provide redundancy (more specifically, how to mitigate risks to reliability).Diodes have two failure modes: short circuit and open circuit. With the exception of rectifiers in a circuit with very high currents, most diodes fail short circuit. That is, short circuit is the most likely failure mode. Imagine your circuit where the two diodes are protecting the BE junction of a transistor from reverse voltages. If one of the diodes fails short circuit it will short the base and emitter connections and the transistor won't work. So the second diode (the one providing redundancy) cannot take over and keep the circuit working. Only if the first diode were to fail open circuit would the second one keep the circuit working and continue the reverse voltage protection. But open-circuit failures for diodes in this kind of role aremuchrarer.In fact, as currently designed, you have made the failure rate of the deviceworse, becauseeitherdiode failing (short circuit, the most likely mode) will make the circuit fail. As an aside, if you want to make a circuit resilient to a diode failing short circuit, you should put the diodesin series, not in parallel.In reality we wouldn't bother with protective diodes unless the circuit sometimescouldapply an excessive reverse voltage to the BE junction. In that case it might be possible to design that out of the circuit.Anyway, I'm not trying to teach you reliability engineering! 😄 My purpose is to give you an example of your "design without understanding" approach to circuit design. I hope you will see that I am not writing this to criticise you. I am giving it as an example of why understanding the basic principles is important when designing a circuit.PS: I meant what I said earlier: it's great that you are thinking about reliability and resilience at such an early stage.