hybridfree/eevblog-posts huggingface dataset:
Bipolar DCDC with bipolar output (battery to 3 Phase converter) - Page 1
Forum section: electronics / projects

author: Amper
author_rank: Frequent Contributor
timestamp: April 11, 2022, 10:15:41 am
content: Hi!Im working on a battery to 3 phase converter, for now to power aircraft electronics at 400Hz 115V from 24V but when things work id like to build a larger version for off grid applications.To power symmetrical loads like motors or heaters just having a single dcdc generating the dclink voltage is enough of cause but when DC offset and or asymetric loads come into play, things start getting interesting. To my knowledge generating a proper neutral taht can handle load in any direction will require my dcdc to provide a positive and a negative rail that are both regulated/ symmetrical even under unequal load.The obvious path is just to use two independant DCDCs, each with its own regulation but mirrored.While this will work im afraid if things go wrong and i loose one rail due to an error in regulation, high load or any other thing i cant think of i will generate a DC offset on teh output of my converter wich can easily fry whatever is connected.Thats why im looking for a topology that allows inductive coupling of the mirrored paths.A converter using an (ideal) transformer would provide me with two rails that are exactly the winding ratio apart, also i could use one output winding and a voltage doubler that will generate symmetrical outputs. However those topologies will all either require a sine input or some kind of inductor to limit peak currents. Sine is not really an option and inductors will "soften" the rails differently, so the coupling will not be there anymore.Is there some other way?Maybe coupling the output inductors?How is this done in commercial 3 phase converters?I just noticed, it does seem to work somewhat if both channels are in continuous mode after the current is high enough.(The screenshot shows my idea about the coupled inductors wich does not seem to work, the transformer was left out and repllaced by the source)

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 12, 2022, 12:48:59 pm
content: Quote from: Amper on April 11, 2022, 10:15:41 amAdd a circuit to detect excessive DC offset and shut down the converters, exactly as what's done in audio amplifiers.
Bipolar output rails from a boost converter? - Page 1
Forum section: electronics / projects

author: prosper
author_rank: Regular Contributor
timestamp: May 19, 2021, 03:09:36 pm
content: I have a few of these little boost converters from ebay. They're boost converters that output +/-15V.What I find interesting - and puzzling - about them is that they only use a single-ended controller (the SOT23 device, it's and MT3608), and a single inductor with only one winding. I'm not aware of any topology that would give a positive AND a negative rail this way, and the datasheet has no reference implementations of a bipolar supply.The only thing that I can think of is that one of the rails is implemented as a charge pump. There ARE a good number of chunky capacitors and diodes on the board.I might take a crack at reversing the schematic, but before I do - am I missing anything obvious? Is this a common configuration? Anyone have any interesting reading, appnotes or the like?

author: mikerj
author_rank: Super Contributor
timestamp: May 19, 2021, 04:15:49 pm
content: ThisTI app notemay be what you are after.

author: prosper
author_rank: Regular Contributor
timestamp: May 19, 2021, 04:27:59 pm
content: oh yes, that helps! The discharging coil serves to charge the flying capacitor when the (output) transistor is off, and the voltage present will be regulated to the setpoint of the positive output. Clever. The negative rail itself then won't be capable of a lot of current, and is not actually regulated all that well, but works well enough for most applications that need negative voltage.Seems like a very useful technique.

author: David Hess
author_rank: Super Contributor
timestamp: May 19, 2021, 08:52:28 pm
content: There is a way to make a bipolar output with a single inductor in a flying configuration but usually a charge pump is used for the negative output.
Bipolar Photoconductive Isolation Amplifier using Vishay IL300 Strange Issue - Page 1
Forum section: electronics / projects

author: aarpcard
author_rank: Newbie
timestamp: October 02, 2019, 01:52:33 pm
content: Hello All,This is my first post here. Not sure if this should be in the projects forum or the "beginners" forum. This may end up being a really stupid, simple question. Digital circuit design is my background, so analog stuff is not my forte.A bit of background:I have an audio mixer connected to a USB soundcard's line out jacks via 25 Foot RCA cables. As such, I have a pretty serious ground loop problem - fairly loud static and hum. Not wanting to use audio isolation transformers due to their expense and potential distortion/non-ideal frequency response I decided to use Vishay IL300 Optocouplers to build an isolation amplifiers for each channel. The goal was to have unity gain, as flat as possible frequency response across the audio range, as minimal as possible distortion, and break the ground loop, so I splurged and got binned IL300's with K3=1.0.I built the below circuits modified from the examples in the IL300 datasheet (only showing 1 channel):Configuration 2 is the design I came up with first. The input and output stages of the amplifier use separate grounds and +/-15V rails generated by two NMH0515SC isolated DC-DC converters. 5VDC and DGND for the DC-DC converters is supplied from a USB port. The line-in signal and ground is completely isolated from the line-out signal and ground. This circuit functions, i.e. passes through the audio signal, but does absolutely nothing to eliminate the noise from the ground loop.Configuration 1 uses a single isolated DC-DC converter to generate +/-15V and GND. The input and output stages of the amplifier share the same power rails and share the same ground. Thus line-in and line-out share the same ground. This configurationcompletely eliminates the ground loop noise eventhough the line-in and line-out grounds arenotisolated from each other.This is exactly opposite how I expected it to work. Can anyone explain where I'm mistaken?

author: moffy
author_rank: Super Contributor
timestamp: October 03, 2019, 10:20:18 am
content: It might not be a ground loop, but induced mains noise in your 25' cables. Try using a cheap car audio isolator to see if its induced noise or a ground loop. Your first configuration doesn't break a ground loop, but might lower the output impedance driving the cable due to the opamp and hence reduce induced noise. It's only a guess.

author: Ian.M
author_rank: Super Contributor
timestamp: October 03, 2019, 11:07:20 am
content: Even if it is a ground loop, you don't need full galvanic isolation to break it. A differential amplifier with high impedance inputs that have a common mode range extending well outside the supply rails, connected to the signal source and the signal source's ground will be good enough as there is unlikely to be more than a few volts between the signal source ground and your local ground.
help choose a multiplying DAC for AC signals - Page 1
Forum section: electronics / projects

author: SArepairman
author_rank: Frequent Contributor
timestamp: March 19, 2014, 01:11:31 am
content: so I need a multiplying dac for AC signals.It is important for me to have a DAC which can natively accept a bipolar input, I.E. I have a DAC that seemed promising, the DAC08, but it would require a offset current to turn into a AC dac, requiring a precision current source (at least a reference + resistor).I would also like inputs that go as high as possible, easily +-15V.Does a DAC like this exist or do I need to use an external current source?complimentary outputs are a must!!!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 19, 2014, 02:26:39 am
content: What bandwidth?

author: SArepairman
author_rank: Frequent Contributor
timestamp: March 19, 2014, 06:45:11 am
content: Quote from: T3sl4co1l on March 19, 2014, 02:26:39 amat least 1 MHz.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 19, 2014, 07:16:27 am
content: You may need a PGA; I think most (R-2R or huge-chain types) roll off below that...Tim

author: SArepairman
author_rank: Frequent Contributor
timestamp: March 19, 2014, 07:36:29 pm
content: Quote from: T3sl4co1l on March 19, 2014, 07:16:27 amthat is an excellent suggestion I was stuck thinking attenuation but now I realize that I can maybe just alter my gain stage so I don't need attenuation.programmable attenuation is useful of course but not necessary for me, I am essentially doing gain trim. There might be setbacks in terms of system drifts but I need to look at PGA before I say anything.ah blast, it seems that they are not bit controlled by have predetermined settings. Perhaps I can use multiple devices (I.E. 3) to get the range of outputs up...
Bipolar "Reverse Bias Safe Operating Area" - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: June 28, 2025, 10:34:13 am
content: Figure 7,https://www.onsemi.com/pdf/datasheet/fjp13009-d.pdfWhat is this telling us?This is a new parameter to me. I see there are two base currents defined. Is this something akin to MOSFET Avalanche breakdown specifications?At a guess,IB1 = I(be), although very large,IB2 = current Icb (reverse)

author: David Hess
author_rank: Super Contributor
timestamp: June 28, 2025, 01:04:59 pm
content: Reverse bias safe operating area is measured when the base-emitter junction is reverse biased, or commonly pulled negative for an NPN transistor. This increases the safe operating area over the condition where the base-emitter junction is only pulled to zero volts.I do not know why the reverse bias is specified as a current; usually it is specified with a forward current and a reverse voltage.

author: Circlotron
author_rank: Super Contributor
timestamp: June 28, 2025, 01:05:03 pm
content: https://en.wikipedia.org/wiki/Safe_operating_area#Reverse_bias_safe_operating_area
Bipolar Stepper Motor Driver Help - Page 1
Forum section: electronics / projects

author: Twistx77
author_rank: Regular Contributor
timestamp: April 16, 2013, 08:13:18 pm
content: Hi, I'm working in a design that includes a stepper motor driver, I've been looking for different IC's in Farnell and I've found one that might work for me.It's the ON's LV8711T. The question that I have is that since I don't want to use it in constant current mode and I¡m not sure if I will need a capacitor for the CHOP pin since I won't use it in constant current mode.I guess not but in that case, should I leave it open or should I connect it elsewhere?I hope someone can give me some help with this since the datasheet doesn't specifies anything regarding this matter.I would also appreciate any other recommend IC to drive a bipolar stepper motor.Thank youDatasheet:http://www.onsemi.com/pub_link/Collateral/LV8711T-D.PDF

author: Short Circuit
author_rank: Frequent Contributor
timestamp: April 16, 2013, 09:19:03 pm
content: No idea about the CHOP capacitor,but why select this device if all you're after is a simple H-bridge driver?Or, why don't you want to use current control? Much better control of the motor with less risk of burning the windings.Also, many stepper drivers exist with the stepping sequence integrated, these can be controlled much easier using STEP pulses and Enable+Direction signals.

author: Twistx77
author_rank: Regular Contributor
timestamp: April 16, 2013, 09:21:42 pm
content: Hi,Thank you for your opinion, I've chosen the LV8711 because it was cheap and also because I've never used one of those that already implement the control of the stepper.Do you have any recommendation?
Bipolar supply vs single supply grounding scheme - Page 1
Forum section: electronics / projects

author: poorchava
author_rank: Super Contributor
timestamp: October 04, 2024, 08:32:50 am
content: I'm designing a thing that has somewhat sizable analog front end, multiple opamps etc. Bipoalr supply like +/-2.5V makes the design more straightforward, but takes more space, digital control signals need levelshifting, there is additional +/- power supply needed. Conversion with single-supply is quite easy (virtual ground potential to some opamp inputs, etc) since the signal path is mostly ac coupled anyway. The decice will be handheld, so I need to go with single supply to dut the component count down.So i have my 5V supply, and will have a 2.5V VGND powered by some push-pull stage (opamp and BJTs?). Easy enough. But the question is: things like RC filters, would you replace GND connection with VGND potantial? How about ground planes? Obviously in this case GND potential is essentially the negative rail, the signal common mode is generally +2.5V from that. Would you connect the internal planes and copepr pours to GND or VGND?I was thinking of the latter. So then VGND will essentially be what used to be GND, GND will be what used to be -2.5V. So also connect all filters to VGND instead of GND. All shields would also be at VGND, not GND.What are your thoughts on this? I'm leaning on making the copper pours and everything VGND potential, but not sure how to design voltage regulators for that, since those would be referenced to actual GND, not VGND.I'm by no means new to the field, almost 20y of experience, almost 10 of which in T&M industry, but somehow it's the first time I have to make a shift like this. Up to now I've almost always been able to use bipolar supplies anytime I has any major analog processing.

author: Salitronic
author_rank: Contributor
timestamp: October 06, 2024, 12:28:02 pm
content: To answer that question you need to ask yourself: what is the reference for the signal at the point of interest?If your split DC supply was ideal, its ac-equivalent circuit would be a short circuit. Therefore with ideal DC supplies you could 'ground' the RC filter to either of the 'real' rails or the virtual ground, it wouldn't make any difference. In practice each of your supply rails comes with its equivalent noise source. If you are dealing with an input or intermediate signal that is referenced to the virtual ground you'd want to 'ground' your RC filter to the virtual ground. On the other hand if you are feeding the output signal to an ADC referenced to the 'real' ground, the RC filter should be connected to that ground to include the noise source from the split supply.The ground planes in general should as much as possible always be the system ground, particularly for purposes of EMI/EMC.

author: Terry Bites
author_rank: Super Contributor
timestamp: October 07, 2024, 04:43:24 pm
content: Signal gnd is Vref.The emitter follower in the splitter can become unstable if not designed correctly.
Bistable Flip/Flop circuit second LED required. (Solved). - Page 1
Forum section: electronics / projects

author: Jim-0000
author_rank: Regular Contributor
timestamp: April 08, 2019, 10:43:15 am
content: I have this little circuit wired up and operational for indicating the state of a device which will be either activated or not.http://www.circuitbasics.com/555-timer-basics-bistable-mode/It is working and doing part of the task required.It shows the LED on until it is triggered via a 4N25 opto coupler.All good.Except that the user would like a (different colour) light on when the 555 flip flop was in the other (or second) state.Can someone advise where a second LED should be wired into this circuit to indicate the alternate stable state please?Jim.

author: Zero999
author_rank: Super Contributor
timestamp: April 08, 2019, 02:03:32 pm
content: Connect another LED between pin 3 and the positive power supply, via a suitable current limiting resistor.

author: Jim-0000
author_rank: Regular Contributor
timestamp: April 08, 2019, 09:17:34 pm
content: Thanks for the prompt reply. I will give it a try this morning.Edit:I just tried it as suggested by zero and it all works fine!I'll mark this thread as solved.
Bit Error Rate Tester Determination of State - Page 1
Forum section: electronics / projects

author: SparkFly
author_rank: Regular Contributor
timestamp: April 23, 2018, 03:22:14 pm
content: I'm looking into making a low frequency (couple of MHz) BERT on a fpga, but am coming across a dilemma when building the receiver to decide upon whether a bit is 1 or 0. How is this decision performed in a typical instrument? I know of some techniques on 'real' systems involve taking multiple measurements and then choosing the 'middlemost' value as the bit state, others apply filtering etc. What is worth considering when designing this for a BERT to measure a system's susceptibility to EMI? Should I just go as simple as possible by using a clock at double the data rate to take the bit state in the middle of the bit? I would think by applying filters/other methods you would also be measuring the receiver;s ability to filter/correct data etc, rather than focusing on the channel itself?Or do commercial BERTs rely upon a variety of input conditioning for each testable comms protocol?Many thanks in advance.

author: mikerj
author_rank: Super Contributor
timestamp: April 24, 2018, 11:58:51 am
content: Quote from: SparkFly on April 23, 2018, 03:22:14 pmA commercial BERT will typically have adjustable decision threshold and phase.

author: Sparky49
author_rank: Regular Contributor
timestamp: April 24, 2018, 04:45:41 pm
content: Thanks for the reply mikerj, I presume you are talking about threshold voltage? What I'm really interested in is how a noisy (ie flickering between 0 and 1) single bit would be arbitrated.I've attached I diagram to better (hopefully) explain what I'm talking about. If you only sample the very centre of a bit, bit 1 would look like a 0, despite it looking very much like a 1. bit 2 would be fine, but bit 3 looks like it might be either. Alternatively if you sampled each bit 10 times and went with a majority to determine the bit, bit 1 would bit a 1, bit 2 0 and bit 3... who knows lol.Is there a standard way of doing it on BERTs, especially if you were more interested on the effects of say emi on a transmission line? i suppose for that you'd want the simplest way of arbitrating a 1 or 0, rather than adding any filters etc?EDIT: Realise I forgot the attachment!

author: mikerj
author_rank: Super Contributor
timestamp: April 24, 2018, 05:20:52 pm
content: The BERs I use make a decision at a single (adjustable in amplitude and phase) point in the eye. An oversampling/majority decision scheme may provide improved noise immunity in practical use but it won't tell you as much about the quality of your signal.Then again these are all running at 10GBits+, so opportunities for oversampling are a little more limited

author: Sparky49
author_rank: Regular Contributor
timestamp: April 24, 2018, 06:09:04 pm
content: Fantastic, thanks very much mikerj, that's exactly what I wanted to hear.May I ask which BERT you use?
BJT between OP and FET? - Adjustable Constant Current Load - Page 1
Forum section: electronics / projects

author: MRAWESOME
author_rank: Newbie
timestamp: April 02, 2016, 11:35:08 pm
content: Ahoy.I am planning out a build of an adjustable, constant current load to test all sorts of circuits. Dave's design in EEVblog #102() simply connects the output of the opamp to the gate of the FET. However, this design uses a BJT between the output of the OP and the gate of the FET:https://www.eevblog.com/forum/projects/project-high-power-constant-current-programmable-load/msg117559/#msg117559I am wondering why? My first guess is that the gate charge is 'dealt with' more easily by the BJT than by the OP. This would make adjustments quicker and so would then make the circuit more stable(?).Is my guess correct?

author: dannyf
author_rank: Super Contributor
timestamp: April 03, 2016, 12:02:22 am
content: Stability I suspect.Being essentially a capacitor, power fets are difficult to drive, especially for high speed opamps.

author: zlymex
author_rank: Frequent Contributor
timestamp: April 03, 2016, 04:33:37 am
content: It is about the stability/overshot and how fast the current follows the setting. It is not necesarry to use a BJT if you don't mind the speed. Various method of compensation can be used to solve the stability problem. Here is the screen shot that I fiddle with those parameters in the hope to achieve the largest phase margin(>100 degree). I added an 10nF capacitor to the FET make things worse.

author: diyaudio
author_rank: Frequent Contributor
timestamp: April 03, 2016, 09:54:47 am
content: Quote from: zlymex on April 03, 2016, 04:33:37 amInteresting analysis, have you taken into consideration the parasitic capacitance components at the at Gate, Source and Drain? @JDaddy has made some similar interesting findings as well. Is it really even necessary to add the pole/zero at the component level (it seems so obfuscated doing it that way) why not introduce it around error amplifier.

author: zlymex
author_rank: Frequent Contributor
timestamp: April 04, 2016, 06:09:33 am
content: Quote from: diyaudio on April 03, 2016, 09:54:47 amThe software I use is Tina 9, there are models build-in for components, therefore those capacitors of a MOSFET are already taken into account when I made the analysis. I added those pole/zero around the error amplifier in order to achieve the largest phase margin for the current source. This is necessary when the load changes such as inductive loads.
BJT theory, testing and graphs (1969 paper) - Page 1
Forum section: electronics / projects

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 16, 2016, 01:01:39 pm
content: http://ibm-1401.info/TransAbnormalitiesIVCurves1969.pdfIf the semiconductor theory is a little heady for you, at least the V/I curves are handy: why they sometimes bend over one way or the other, give or take base voltage/current; what second breakdown is; and what all of that means, if you do want to look deeper at things.Tim

author: danadak
author_rank: Super Contributor
timestamp: September 16, 2016, 02:20:09 pm
content: Other good references, series by Fredericksen at NSChttp://www.goodreads.com/author/show/1610592.Thomas_M_FrederiksenSome general and indepth stuffhttp://101science.com/transistor.htmPhysics -http://www.wiley.com/WileyCDA/WileyTitle/productCd-0471329983.htmlhttp://www.wiley.com/WileyCDA/WileyTitle/productCd-0471143235.htmlMeasurementsftp://bitsavers.informatik.uni-stuttgart.de/pdf/tektronix/concepts/062-1009-00_Semiconductor_Device_Measurements_Apr69.pdfThere was also a note on high field breakdown and SOA done by Mot, but I cannot find reference.Regards, Dana
BJTs with freewheeling diode on the same substrate - Page 1
Forum section: electronics / projects

author: madires
author_rank: Super Contributor
timestamp: February 28, 2014, 02:15:52 pm
content: While working on a new version of the transistor tester firmware I came across the BUL38D which is a NPN for switching applications and it has an integrated freewheeling diode on the same substrate. The funny thing about it is that the freewheeling diode on the same substrate creates a parasitic PNP transistor (draw the junctions and you'll see) which even has a higher hFE than the NPN. Do you know of any other BJTs built the same way? Are there also PNP versions? Or is the BUL38D just a very rare example of that kind of BJT?Possible candidates:- BUL58D- BUL381D / BUL382D- any more?

author: SeanB
author_rank: Super Contributor
timestamp: February 28, 2014, 06:23:21 pm
content: BU208D, BU508D. Pretty common as line output stages, and there are a whole host of 2SC devices as well.

author: madires
author_rank: Super Contributor
timestamp: February 28, 2014, 07:48:20 pm
content: Quote from: SeanB on February 28, 2014, 06:23:21 pmAlready got the BU508D, but it's low value base emitter resistor causes other issues. Any idea about specific 2SCs?
B&K CRT 465 mod long term effects? - Page 1
Forum section: electronics / projects

author: W7NUK
author_rank: Newbie
timestamp: February 16, 2017, 06:38:41 pm
content: I have a CRT tester and on the heater voltage setting the meter was reading way off. It was way high on the high ranges. 13v on the meter equaled 12.4v at the plug. I tested a bunch of capacitors in parallel with the meter hoping to solve that. No go. But I found a 1n4001 diode in parallel with the meter made it super accurate. But that messes with my emissions reading. It was reading 180ua instead of 480ua before. I removed the diode's anode off the back of the meter and attached a wire to run over to the wiper of the 20kohm pot so it was switched out when I'm in the emission position of the mode select switch.What I want to know is what effect does the diode have that's stabilizing the meter? Why is it working there? And what effect does the diode cause when I'm in the emissions position? Wil it screw with the tester harming anything? I'll include a schematic. The diode's cathode is attached onto the back of the meter on the negative terminal. The anode has a wire running to the the wiper of the 20kohm calibration pot. The meter is near the mid left.Thanks

author: W7NUK
author_rank: Newbie
timestamp: February 16, 2017, 06:40:10 pm
content: Here's where I found the schematic.https://elektrotanya.com/bk_465_crt_tester_sch.jpg/download.html

author: W7NUK
author_rank: Newbie
timestamp: March 20, 2017, 01:36:40 am
content: The meter already has a diode in series with it I just happened to have put a diode in parallel with the meter which is after the diode and resistors for the meter. My guess is the meter was recieving more current then it is supposed to as its a 200ua meter. And the diode keeps the the voltage down across the meter and such also the current through the meter. As its a 1n4001 it should be somewhere around 0.7v drop on the diode. I'm guessing as the voltage rises using the heater adjust control the voltage and current rise on the meter. But the voltage would rise too much at the higher end of the heater ranges allowing the meter to deflect too much for the acual heater voltage. The diode acts to keep the voltage across the meter lower and as such the current as well. Because it should then start conducting slightly as the voltage rises higher. Even if it's a little current flowing through the diode it's enough to now make it dead accurate at any voltage. After I retouched the potentiometer for calibrating it of course. Before it was fine at low voltages on any range and higher voltages on the lower ranges. Once I reached the higher voltages on the higher ranges it would be so far off. Good thing I never tested any 12.6v tubes. As I have none!I'm guessing the diode shouldn't have an effect on the emission circuit as its switched out of the main circuit in the emissions test position. It's also in series with the orginal diode used to rectify the AC to DC for the meter to read right. If the orginal circuit did just fine then it shouldn't have a problem with my modification.Nice that I finally got this. I was worried about it causing series problems.
Bk Precision 1570A oscilloscope repair and calibration - Page 1
Forum section: electronics / projects

author: jcrubin
author_rank: Frequent Contributor
timestamp: September 25, 2017, 12:58:00 pm
content: This is the repair and calibration of this particular 4 channel BK oscilloscope not unlike a Panosonic model mentioned in the video, more information to follow during the calibration portion in subsequent videos.Part 1 of 5

author: jcrubin
author_rank: Frequent Contributor
timestamp: October 02, 2017, 12:35:01 pm
content: Part 2 of 5

author: jcrubin
author_rank: Frequent Contributor
timestamp: October 09, 2017, 12:25:06 pm
content: Part 3 of 5

author: jcrubin
author_rank: Frequent Contributor
timestamp: October 16, 2017, 11:48:28 am
content: Part 4 of 5

author: jcrubin
author_rank: Frequent Contributor
timestamp: October 23, 2017, 12:06:44 pm
content: Part 5 of 5 - The final video
B&K type 2409 Electronic Voltmeter 2Hz-200kHz, test, repair, teardown - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: May 12, 2022, 07:57:17 am
content: i got two models, 2 and 3 tube designs of the same producthttps://youtu.be/GGD43aK1qTUone match the schematic you find on radiomuseum, the other one dont,so it was a bit tricky to repair with out the correct schematic, so i had to make my own schematic,

author: PeiCB
author_rank: Newbie
timestamp: July 10, 2022, 04:14:08 pm
content: HelloI have a faulty three tube version which I will try to repair.Some of the DC-voltages are quite out of range so I plan to test the capacitor leakages first.Any recommendation how to access the component side of the main board in order to de-solder?I have schematics for both two- and three tube versions.

author: oz2cpu
author_rank: Frequent Contributor
timestamp: July 12, 2022, 08:40:20 am
content: i simply used tweezers and sucked away the solder, then i could replace parts on the pcbwhile all is still assembled, i was too lazy to pull it all apart :-)i think there is plenty of space
B&K8500 300W load fail , Help needed please :)  - Page 1
Forum section: electronics / projects

author: eevblogfan
author_rank: Frequent Contributor
timestamp: August 09, 2013, 12:29:29 pm
content: HeyNope it ain't mine , but I started to perform callibration for that unit . I remember the voltage range didn't let me test it above 20V or so .. I can't remember what I did but I think I managed to increas it to the full voltage range ,sorry I am writing from my home and that case is open since 2 monthes or so . hence I can't remember the ranges of the unit ...well .. so what's the fail ?the unit doesn't draw current at all ,* the display is fine ]*the controls are responsiveI can't remember what else I've checked but nothing too obviuse here ...so I asked for permission to open the device . I got green light and so I did ..Inside there was no gate resistors blown , and no other *clear* vissualy harmed component ... not one I could see anyhow ..can the fets be burned out , Although there was no power on the supply ? ( I think it aws set to 5V . and Current set to max 2A )is it safe to put voltage between one of the fets and limit the current to few mA .. and then slowly raise the voltage to say 5V ? ..I am asking because I don't have the schema In order to see id ther's something obviuse to be caution about ...befor even that attempt ... I have meassured the gate(s) voltage(s) while setting the load to draw 0.5A or so .. and the voltages should be the max the driver can output here right >? ( nothing connected to the front binding posts .. ) and I got nothing but 0V ( or 30mV or so .. )the menu is okay , so the Cpu is okay right ?can someone please help me with new path to look for ?service manual with full schematics is going to help here .. just sayingthank you in advance

author: saturation
author_rank: Super Contributor
timestamp: August 09, 2013, 07:38:19 pm
content: Backtracking, you received the unit damaged? Also can you post photos of the issues you wrote about, it'll make it easier to understand.
Black foam for components - Page 1
Forum section: electronics / projects

author: NivagSwerdna
author_rank: Super Contributor
timestamp: February 08, 2021, 03:46:22 pm
content: I would like to get a small supply of the black stuff that you can put your DIP packages in during shipping.It seems to come in two flavours... the black stuff that is squishy and the pins don't really get stuck... I don't like that.And the lovely crunchy black stuff that the pins get nicely embedded in.What is the name for the later? Any standard sources?

author: CJay
author_rank: Super Contributor
timestamp: February 08, 2021, 03:52:41 pm
content: https://www.teknis.co.uk/category/esd-foam

author: jfiresto
author_rank: Frequent Contributor
timestamp: February 08, 2021, 04:51:47 pm
content: Quote from: NivagSwerdna on February 08, 2021, 03:46:22 pmI believe you are after semi-rigid polyurethane.

author: Benta
author_rank: Super Contributor
timestamp: February 08, 2021, 06:01:07 pm
content: It's from 3M.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: February 08, 2021, 11:51:05 pm
content: "Pin Insertion Foam" looks very helpfulThanks all
monitor's Black frame insertion . - Page 1
Forum section: electronics / projects

author: Vladimir Svyryd
author_rank: Newbie
timestamp: September 27, 2021, 03:26:49 am
content: Good day community.I came with idia and lack of knowledge.I have monitor prety good . To me.It have dow side , one tech option is missing .Black insertion frame. It increase clarity of picture during fps game.I need help to find stable ( constant signal ) end or start or some middle frame time .So i cud drive back light on- of to get effect of BIF. (Switch of back light between frame's.If some one familiar with display port's structure and decoding , or display matrix driver's chip's , pls help me ,point me whear to start, or how to create this HARD MOD ,HACK FOR MONITOR'S

author: Vladimir Svyryd
author_rank: Newbie
timestamp: October 02, 2021, 06:43:47 pm
content: Still up.From what i readDecoding traffic in dp cable will be to hard.Now i learning driver's for panel's . Probably that will be the way..
Black Magic Fun: 1GHz signal generator? - Page 1
Forum section: electronics / projects

author: hlavac
author_rank: Frequent Contributor
timestamp: March 30, 2013, 04:16:51 pm
content: I thought I would attempt to have some black magic fun and try to make a 1GHz test signal generator to test frequency counter prescalers using nothing more than a few transmission lines on a PCB and handful of HF transistorsI'd like to base it off a standard 100MHz crystal oscillator can I have, and basically make a 10x frequency multiplier.Basic idea is: Make a short 500ps pulse on rising edge of the 100MHz clock, send it along a transmission line with 10 taps spaced 1ns apart, and copy the pulse on the output as it passes each tap! Collect the tap signals using equidistant traces to the output... I should end up with 10 500ps pulses spaced 1ns apart, i.e. 1GHz signal!To make the short pulse, I would need to sharpen the edges of the input clock somehow to be fast enough to serve as 1GHz edges, then use source side terminated transmision line shorted on the end that will generate positive pulse on rising edge and negative pulse on negative edge, and then cut off the negative pulse (have some really fast transistor turn on on the positive pulse?). Or the other way around...Now for the questions:Can anyone recommend some high frequency capable transistors that work in gigahertz ranges?Are there diodes that fast? I presume not... PIN diodes are not really diodes on HF right?Any good sources of info on controlling impedance of PCB traces / transmission lines?

author: hlavac
author_rank: Frequent Contributor
timestamp: March 30, 2013, 06:15:14 pm
content: Yes, but where is the fun in buying that?Here is the wholesilly conceptI had in mind.

author: C
author_rank: Super Contributor
timestamp: March 30, 2013, 09:58:08 pm
content: Not my thing,but in fun, it sounds like you are talking about a wagon wheel with a 1 ns time between spokes.zap an LC with the right timing and you have an oscillator.So, If you have a complete wheel you have a chance to build on the energy from before.going crazy further, what if you connected your square wave 100 Mhz logic output to a wheel with the proper delay such that the wheel reinforces the logic output and the logic output reinforces the wheel.http://en.wikipedia.org/wiki/Ring_oscillatorC

author: nctnico
author_rank: Super Contributor
timestamp: March 30, 2013, 11:13:33 pm
content: Quote from: hlavac on March 30, 2013, 06:15:14 pmMost of those boards from Ebay don't make a clean 1GHz. There is loads of harmonics so you'll need filtering.

author: cwz
author_rank: Newbie
timestamp: April 22, 2013, 04:49:07 am
content: There are tons of frequency synthesizers are out there that can easily do this. For example, see this part from Silicon Labs:https://www.silabs.com/Support%20Documents/TechnicalDocs/Si5325.pdfTI, Analog, IDT, Hittite (if you want stuff really in the microwave range), etc.As was already mentioned on here, you're probably just best off buying a ref board from one of the manufacturers. It will almost certainly cost you more to make a one off, even just the cost of the PCB fab.
Black Star Model 3225MP – Conversion to Illuminated LCD or LED? - Page 1
Forum section: electronics / projects

author: Chris56000
author_rank: Frequent Contributor
timestamp: October 19, 2021, 05:07:33 pm
content: Hi!I received received a British–Made Black Star 3225MP mains–powered LCD bench multimeter in nice condition, but the LCD on it is too dark and murky for my eyesight!Can anyone recommend an LCD that can be illuminated from behind, if not, how do you remove the silver backing from the original without damaging it?There is no service manual available for this meter available for download as of looking today, but I believe the meter is of the straightforward '7106 based type!Alternatively is conversion to LED by replacing the '7106 to a '7107 feasible?Chris

author: wraper
author_rank: Unknown
timestamp: October 19, 2021, 05:12:17 pm
content: If there is where to put LEDs, illuminate it from the side edges.QuoteDon't do that. That reflector film is polarizing and you will destroy the display.
Black zinc is the new olive drab cadmium? - Page 1
Forum section: electronics / projects

author: rounin
author_rank: Regular Contributor
timestamp: March 05, 2023, 09:49:26 pm
content: We've been using 38999s in one of our products, with the classic olive drab cadmium.This year, I wanted to start moving towards ROHS compliance. We discovered that finish type "Z", black zinc nickel, is mostly in stock, a near drop in replacement spec wise and is mating/galvanically compatible with the old cadmium parts which is nice as we burn down stock. Also not too much more expensive.I guess black is the new olive drab.Anyone else switched old mil spec parts to ROHS? We're also looking at using electroless nickel to save a few $, but it looks like the environmental specs aren't as good and it isn't backwards compatible with cadmium. I'm somewhat surprised I haven't seen BZN yet out in the wild on some of the projects I've worked on (avionics).

author: coppercone2
author_rank: Super Contributor
timestamp: March 05, 2023, 10:05:10 pm
content: well it seems that when there is a war the stuff that ends up being used is ancient when they run out of flashy stuff so I am not sure many people are going to sub par processes

author: Swainster
author_rank: Frequent Contributor
timestamp: March 06, 2023, 05:00:59 am
content: At my old job we changed to black zinc nickel thanks to RoHS. That was for roadside infrastucture, back home in the UK, pre-brexit (though I would guess that RoHS is still a thing)

author: coppercone2
author_rank: Super Contributor
timestamp: March 06, 2023, 05:24:32 am
content: Well I think its the coating that might be on some machinists rules IIRC, my ruler is black nickel coated, I guess zinc? (it was not listed in advertising as zinc). It had some corrosion show up on it after being stored in a somewhat damp place for a while. I cleaned it up with some kind of metal polish, and recoated it with grease for protection, but it looks kinda like it has splatter of missing surface material when you look at it with the correct angle. I think it had like 'white spots' growing on itnevermind, mine is coated with 'black chrome' which I regard as shit, not black nickel. Not sure if its similar. Because the ruler was defiantly rubbed with 3-1 oil and it was stored near many other objects, which did not fail.

author: rounin
author_rank: Regular Contributor
timestamp: March 06, 2023, 08:56:47 pm
content: For some reason amphenol PCD seems to only make the backshells in zinc cobalt even though the faces are zinc nickel. weird. Will order a batch of parts this week, might sit a new cable assy outside for a few weeks.
BlackBox: binary, lightweight communication protocol handler code generator. - Page 1
Forum section: electronics / projects

author: cheblin
author_rank: Newbie
timestamp: February 17, 2018, 04:52:20 pm
content: Hello!Recently I finished theBlackBox: binary, lightweight communication protocol handlercode generator.And nowcomplete new projectwhich converting ofMAVLinkprotocoldescription XML fileintotheBlackBoxformatIt is clearly demonstrates the maturity ofBlackBoxand its comparatively greater capability againstMAVLink.Everything works just fine, all tests are passed successfully. Therefore I decided to share this with you, guys.What are the advantages?TheBlackBoxformat of the protocol and the network topology description file is presented as plain java source - more compact and familiar for the programmers, instead of XML format in theMAVLink.Plain java file format supported by many development environments with all the refactoring capabilities.inheritance of packet fields;Base 128 Varintdata compressionadditional data formats:fields with the built-in structure of multidimensional arrays;fields of sparse multidimensional arrays;bit fields;fields with the built-in structure of multidimensional arrays of bits;UsingBlackBox, you can easily establish communication not only between microcontrollers, mobile devices but also between the ordinary computers. And what is important, without time and effort waste. In fact, the generatedBlackBoxcode can become the skeleton of your distributed application. The programmer will just have to add handlers to the packet's reception events, as well as the logic for creating the package, populating it with data and sending it to the recipient.BlackBoxgenerates the source code in the following programming languages:JAVA, C#, C.Forget about:MQTTMQTT-SNCoAPSMCPSTOMPXMPPXMPP-IoTMihini/M3DAAMQPDDSLLAPLWM2MSSIWithBlackBoxyou can build you own protocol, fit to only your project needs. You will get very efficient, fast, working overUSARTorTCP/IPprotocol.Here is an example of demo projectto control from Android based mobile, blinking LED on a board under STM8S103F3P6 via Bluetooth UART on HC 08.

author: Leo Bodnar
author_rank: Frequent Contributor
timestamp: February 17, 2018, 10:34:23 pm
content: Thanks for the list of references. I can never remember MQTT acronym when I need it.Quote from: cheblin on February 17, 2018, 04:52:20 pm
BLDC BEMF - Page 1
Forum section: electronics / projects

author: vinodkaruvat
author_rank: Newbie
timestamp: May 25, 2014, 02:13:38 pm
content: Hello Friends,I am trying to build my own ESC (Brushless DC controller) and I managed to get the motor running starting from a ramp to a steady PWM duty Cycle and Commutation period and these are the BEMF waveforms that I see. My question is, where is the "zero crossing event" and why is it different ,somehow inverted,from the regular BEMF waveforms displayed on various documents and notes. I have attached the images in this thread.In the 2 images, how can i look for '0' crossing. Its like high and then falling. It should be the verse and should begin at a much lower voltage valu and rise up to almost peak or so(depending on the duty cycle).Here-in, it is almost impossible to detect '0' crossing. Also, in my scheme I am PWMing the upper MOSFETS, with the lower ones being used/made high during relevant commutations. Kindly help me out pls.

author: muvideo
author_rank: Frequent Contributor
timestamp: May 25, 2014, 07:04:36 pm
content: hello,if you want to peek inside a working BLDC ESC firmware check this:https://github.com/sim-/tgy/blob/master/tgy.asmor this:https://github.com/bitdump/BLHeliReversing the schematic of a cheap model ESC built around an Atmega8is pretty easy and can be a good starting point.As for the zero crossing detection, afaik model ECS measure open leg voltageagain a "virtual neutral" generated using 3 resistors star-connected to the 3 phases.
BLDC Controller 24C LiFePO4 ( 72V .. 87.6V ), 200A  - 1phase power output design - Page 1
Forum section: electronics / projects

author: nerozero
author_rank: Newbie
timestamp: July 22, 2025, 02:05:10 pm
content: Hi there,I do not have much of the experience designing high current/"high" voltage things, so I did something I think "should work" and I will humbly ask you to write some critics on this board... ( Please don`t beat me hard :)So, lets begin, with the circuit, here is what I planing to squeeze from the board:- Operating voltage: 24C LiFePO4 ( 3.0 .. 3.65 cell ) - 72V .. 87.6V- Continues Phase Current: 200A- Peak Phase Current: 300A- PWM frequency ~ @19KHz ishPower MOSFET -PSMN1R0-100ASE- a beast transistor capable of handling 430A Ggs=100V, Rds_on=0.82mOhm, ~ $8 eachGate Driver -1EDB8275F- isolated, 5A/9A, Diff-input, Separated Source/SinkSensing current -INA241A3- gain 50V/V, 110V-CMR*CircuitI have question regarding placing a gate driver close to power MOSFET. I decided to place them on the power board to reduce gate ringing because of high gate currents and capacity. But I'm scared of switching EMI can do some weird things with the driver itself. For my first routing iteration, I placed it right above the power MOSFET but later I shifted it a bit to the side. If someone could explain the common practice of driving high capacity gates....*PCB designI'm not relying on the PCB copper as a major carrier of high currents. All power lines before and after FETs will be filled with 1mm copper strip or 1.5mm copper wires.After estimating worst case scenario resistance between wires and FETs, resistive power losses (board) totaling @300A 6..8W.Power Losses on the FETs, fully on, excluding switching losses ~41W @200A, 93W @ 300A.I have run an LTSpice simulation using this transistor and various inductive load, and cannot produce any ringing, switching is looks like instantaneous ( Toff ~60ns ltspice, 99.6ns calculated worst ). But not sure if I'm calculating the switching time correctly. I'm purely rely on the assumption - transistor gate is a capacitor, and not counting for Gate-Drain capacitance and Miller Effect.( Not sure how to write formulas here, but you can find some of my calculation on the circuit diagram )The reason I have selected this transistors - the heatsink pad is on the back side of the transistor. The transostor itself is capable of conducting 1.4KW of power @t=25C. I have more modest requirements.I was thinking, how can I improve heat dissipation, so I'm thinking, what if I make a small Aluminium-Substrate board with 2 pads (for isolation) in size of FETs rear pads, and then solder this aluminium board directly to the FETs back using low melting point solder, eg Sn42/Bi58 - 135C, as result - insulated, single larger pad for mounting to the heat-sink . But I'm not sure, if this will be a better solution then simple silicone pad. Any ideas ?PS.This is my first time posting here... and I not sure how to properly upload images.Thanks in advance,MeNot sure why my circuit wasn't attached