hybridfree/eevblog-posts huggingface dataset:
High Voltage Generator Mosfet drive flyback transformer - Page 1
Forum section: electronics / projects

author: mu34tant
author_rank: Newbie
timestamp: June 29, 2022, 11:14:48 pm
content: I want to use this driver board (https://www.ebay.com/itm/384300834133) with this transformer (https://www.ebay.com/itm/402679163644). The driver board is designed for 12v. The transformer is primary is setup for 125v. The driver board uses UC3845b timing chip and can be powered offline. I will have a 125v source (https://www.ti.com/lit/ds/slvs036n/slvs036n.pdf) figure 13. I am going to use this mosfet that has characteristics of the 110n8f6 except a much higher Vds (https://www.mouser.com/datasheet/2/196/Infineon-IPP051N15N5-DS-v02_01-EN-994624.pdf) 051n15n5. There will be a common ground for the 12v and 125v supply. There is a 1ohm 5w resistor between 12v supply and mosfet source. I was thinking of going with a 0.1ohm 5w resistor between 125v source and 051n15n5 source. Is this a good idea?
High voltage, high current MOSFET based analogue switch - Page 1
Forum section: electronics / projects

author: perdrix
author_rank: Frequent Contributor
timestamp: December 09, 2023, 05:44:46 am
content: I'm trying to find an analogue switch that will handle at least 30Vrms, and at least 3.5Arms(100Watts into 8 Ohms).If there ain't no such animal off the shelf, how would I build one?Do the available power supply/gate drive limit this?Failing that are there any relays that don't suffer from dry-switching problems at low signal levels but that can handle with this type of signal?PS if could find these packaged as the equivalent of a DPCO (DPDT) relay even better, but I doubt that exists.

author: moffy
author_rank: Super Contributor
timestamp: December 09, 2023, 06:26:03 am
content: The following reference shows a photovoltaic operated MOSFET AC switch:https://toshiba.semicon-storage.com/ap-en/semiconductor/application/smart-plug/articles/ac-switch-example-using-photovoltaic-coupler-and-mosfet.htmlalso:https://www.bristolwatch.com/ele3/1g.htmhas an example.Photovoltaic switches are relatively slow to switch.P.S. You will need to choose the devices to suit your application.
high voltage inverter circuit - LOTS of noise when powered from LDO - Page 1
Forum section: electronics / projects

author: ChristofferB
author_rank: Frequent Contributor
timestamp: November 30, 2019, 07:41:27 pm
content: Hi, so I'm having this issue with a high voltage generator circuit I've made for a DIY geiger counter.It's the inverter circuit from an electric fly swatter. I havent traced the circuit but it's a completely standard topolygy seen in those, a 5-pin transformer, a transistor and some resistors on the input side, a series diode and a parallel capacitor on the HV side.I've modified the output side slightly, putting a series resistor to limit current before the HV capacitor, and then a string of zener diodes and resistors to reach around 400V. A bit crusty but it has worked great so far. Problem is, I've always operated the circuit with two power sources: a 9V battery feeding the audio amp and a 7805 regulator to feed some digital logic, and 2 AA batteries for the HV supply. This is awkward though,and now i've replaced the 2 AA batteries with a L78L33ABZ fed from the 5V reg. Now there's a HUGE amount of noise everywhere, with 50 mv ripple between the 9V battery terminals, and almost half a volt on the 78L33 output! Issue is, if I add smoothing capacitors on the 3,3V reg output, it changes the frequency of the HV inverter, easily detected because it's in the audible region both before and after.How do I solve this? CAN i even solve this, or is the 3,3V reg just unsuitable for the purpose?Thanks in advance.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 30, 2019, 08:31:21 pm
content: It's drawing more than 100mA, get a bigger regulator.Tim

author: ChristofferB
author_rank: Frequent Contributor
timestamp: November 30, 2019, 08:56:42 pm
content: Ah. So the oscillations is the regulator over-current'ing and then switching off repeatedly? That makes sense! I'll get the 1.5A version, thanks!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 30, 2019, 09:20:50 pm
content: Not switching off, limiting and the load browns out.Unless you have other loads on the supply, and as long as you have enough output, it probably doesn't matter.The linear regulator(s) and always-on HV supply won't do you any favors for battery life, of course.Tim

author: ChristofferB
author_rank: Frequent Contributor
timestamp: November 30, 2019, 09:31:22 pm
content: well, it matters because there's an audible screech on the AF output!But lets say battery life isn't really an issue, is there anything wrong with putting the HV circuit directly on 5V with a dropper resistor in series to drop the voltage to 3V?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 30, 2019, 09:47:39 pm
content: It shouldn't care much, no.Tim
High Voltage LCD Driver HI-8010 alternative - Page 1
Forum section: electronics / projects

author: R_A_F
author_rank: Newbie
timestamp: September 25, 2021, 06:28:08 pm
content: Hello,I'm converting an old piece of avionics for sim use. It has a liquid crystal display with an integrated IC to drive it. The whole thing is pretty simple. Two knobs (dual concentric encoders) and a display. Well due to my lets say carelessness, I've managed to kill that driver. It's a Holt HI-8010. I've looked everywhere for a replacement, no joy. It's a 30 volt (-30V to 0V) display driver. Link to the datasheet - (http://www.holtic.com/documents/90-hi-8010_v-rev-gpdf.do).Is there any LCD aficionado here who could tell me if there's a suitable off-the-shelf alternative for such driver? Could I possibly use a VFD display driver and limit its voltage?Thanks for any input.Here's a photo of said display:

author: coromonadalix
author_rank: Super Contributor
timestamp: September 26, 2021, 02:31:26 am
content: Your luck will be to get a quote for the part ??https://www.digipart.com/part/HI-8010SM-50https://www.win-source.net/holt-integrated-circuits-inc.-hi-8010sm-32.htmlthis part seems unobtanium ??

author: dmendesf
author_rank: Frequent Contributor
timestamp: September 26, 2021, 03:58:05 am
content: If you have space you can program a small microcontroller (PIC?) to emulate the shift register and use a totem pole per pin to do voltage translation. Can fit an small board.

author: R_A_F
author_rank: Newbie
timestamp: September 26, 2021, 12:09:53 pm
content: Quote from: coromonadalix on September 26, 2021, 02:31:26 amI contacted Holt directly as well. We'll see. I was hoping someone would know a possible alternative to that IC. Pretty much all of the mainstream LCD drivers are low voltage.

author: R_A_F
author_rank: Newbie
timestamp: September 26, 2021, 12:10:55 pm
content: Quote from: dmendesf on September 26, 2021, 03:58:05 amThanks. Yeah, if I can't find a replacement I'll have to resort to building my own driver.
High voltage leakage / breakdown tester project - Page 1
Forum section: electronics / projects

author: TheDefpom
author_rank: Frequent Contributor
timestamp: August 15, 2018, 06:17:28 am
content: I have been working on a project for a little while for a high voltage leakage tester.It is arduino based, and is actually pretty simple, it generates a DC voltage up to about 500V (depending upon how it is constructed), the arduino measures the supply and DUT voltages, and also the voltage across a current shunt. This is then displayed on an LCD.I wanted to make this after coming across a problem with a high voltage transistor which was leaking and shorting only when exposed to high voltages (when I was repairing my Fluke 5200A AC calibrator), I had no way of easily testing, so I wanted to build something to do it, it can also test for capacitor leakage, or anything you need to check the current draw of at high voltages.I have the unit completed (sure it could still be improved further but it does what I set out to do) the video series is on my channel, I am releasing the project, code, gerbers, eagle design files etc so that anyone else can build one too, should be easy to make the design choices and do the build after viewing the videos.The final video is scheduled to go live on Saturday morning, I will post add it here too once it is live.Part 1 (experiments)https://youtu.be/ZiIs51Hmw24Part 2 (more experiments)https://youtu.be/M2OIeLoNTyEPart 3https://youtu.be/pIapvtBjeZgPart 4https://youtu.be/dfjhZ9M052kPart 5https://youtu.be/3uy47Ye6_aQPart 6https://youtu.be/ptXElF7cFQUPart 7Coming soon...

author: TheDefpom
author_rank: Frequent Contributor
timestamp: August 17, 2018, 09:22:45 pm
content: Part 7All project and design files are here:http://www.thedefpom.com/projects/index.php
High voltage medium frequency AC switch - Page 1
Forum section: electronics / projects

author: poorchava
author_rank: Super Contributor
timestamp: June 07, 2013, 10:03:13 am
content: Hello,I have a design, which involves switching ~200 Vpp, ~1kHz AC signal (in other words: EL driver + sequencer). I have seen it being done with phototriac+triac (like the sparkfun boards).Phototriacs are available only in fairly large packages (smallest is 6-lead smd-dip 0.1"), and so are triacs (smallest I have found is SOT223) and i need the pcb to be as small as possible.Do you know of any more compact ways to switch such signals? I was thinking of SSRs, but the prices are a blocker (suitable ones from omron and panasonic are ~4-5€ a piece).

author: Rerouter
author_rank: Super Contributor
timestamp: June 07, 2013, 11:14:13 am
content: the fact your switching 200V means your going to be hard pressed finding much more compact as you have to worry about clearance issues,

author: Paul Price
author_rank: Super Contributor
timestamp: June 07, 2013, 12:54:33 pm
content: It is easy enough if there is enough space to switch high currents, but I cannot imagine anything smaller than the .1-in pin to pin packaged 6-leaded triac being available. Part of the problem is that the package size has to be big enough to handle the high voltage and currents to be switched. My way below takes up a lot of room. Leakage paths and arc overs are a problem with tiny dimensions. Seems with small project volumes and a tiny space requirement that 4 to 5 euro is a bargain for a tiny SSR.There are many ways. Use a high speed (if required for your application) opto-isolator that directly controls the TRIAC in all 2 or three quadrants of possible triggering with a single negative bias voltage (resistor current limited 24mA applied to the gate). Motor control circuits have been doing this for years in high current 240V appliances like washing machines.The problem here then is how to generate the negative voltage... there are many easy solutions to this. In one of my projects I just stole the 240V cellphone regulated power supply circuit out the tiniest cellphone charger I could find to supply the bias voltage. If you have both ends of the 240VAC just add a tiny transformer and rectifier and filter cap for the bias.
High voltage PNP in DPAK package...... - Page 1
Forum section: electronics / projects

author: Smokey
author_rank: Super Contributor
timestamp: May 06, 2016, 07:54:21 pm
content: I'm having a hell of a time finding a second source for a high voltage (400V) PNP transistor in a DPAK package.I'm using the Rohm 2SA1807TLP now but it's not in stock anywhere. Something similar to that would be prefect but I'll take anything close that has the right package at this point.There are lots of parts in smaller packages like SOT-23, SOT-223, and TO-92 but nothing in the bigger surface mount packages.Any ideas?

author: danadak
author_rank: Super Contributor
timestamp: May 06, 2016, 08:19:33 pm
content: Something here -http://www.diodes.com/catalog/Transistors_%3E100V_118Regards, Dana.

author: Smokey
author_rank: Super Contributor
timestamp: May 06, 2016, 09:02:06 pm
content: The closest diodes inc looks likehttp://www.diodes.com/catalog/Transistors_%3E100V_118/MJD350_7345it's only 300V

author: edavid
author_rank: Super Contributor
timestamp: May 06, 2016, 09:13:44 pm
content: MJD5731 is 350V

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 06, 2016, 09:51:39 pm
content: Nope, not much.Any chance you can mod it to use, say, depletion mode MOSFETs?Tim

author: Smokey
author_rank: Super Contributor
timestamp: May 06, 2016, 10:00:37 pm
content: Unfortunately not. The circuit was originally set up to use one of the smaller packages, but I increased it for creepage and clearance reasons. The layout is pretty tight already around the DPAK. Not much room for alternate circuits without tearing up a TON of other stuff.

author: Smokey
author_rank: Super Contributor
timestamp: May 06, 2016, 10:05:00 pm
content: Quote from: edavid on May 06, 2016, 09:13:44 pmIt looks like I'll have to evaluate if 350V is enough. That might be the way I'll need to go and see if it works in the circuit.

author: danadak
author_rank: Super Contributor
timestamp: May 06, 2016, 10:35:33 pm
content: You could contact appropriate vendors to see if they would do a test offat 400V for you, maybe a lifetime buy would incentivize them. Keep inmind if datasheet says 350, the actual test has margin in it. And characterizationdata to be a xxxV part has to show yield with margin, usually one sigma ormore.Regards, Dana.
High voltage PSU Mosfet choice - Page 1
Forum section: electronics / projects

author: MarcusFunt
author_rank: Contributor
timestamp: August 20, 2022, 10:53:18 am
content: Hi!I am building a device for a national competition ("Unge forskere") That should be able to sterilize hands with nothing but electricity.For this project, I need a High-Voltage power supply, capable of delivering 12(or so)kV at 30-100khz.Therefore my head automatically went to the very popular "ZVS driver" because I want a very efficient operation without much heat as it will be placed in a closed box.You can look at my current schematic in the attached picture.I modeled the schematic in lTSPICE and found that 71v spikes occur at startup, and therefore can't use the 60v IRFZ44N I originally wanted to use.Now the problem is that I don't know what other MOSFET I can use.I don't care if it is SMD or THT.I found a few FETs I think will work, but I'm not certainhttps://www.mouser.dk/ProductDetail/onsemi/NTP011N15MC?qs=DPoM0jnrROX1k1aAlpufTw%3Dhttps://www.mouser.dk/ProductDetail/onsemi-Fairchild/FDP085N10A-F102?qs=0lQeLiL1qyaFktU8QMby%252BQ%3D%3Dhttps://www.mouser.dk/ProductDetail/Infineon-IR/IRLR3110ZTRPBF?qs=Z8%252BeY1k3TILcI4snfu078g%3D%3DAny help, both with MOSFET choice and flaws in my design are greatly appreciated

author: jonpaul
author_rank: Super Contributor
timestamp: August 20, 2022, 12:50:16 pm
content: VERY DANGEROUS IDEAHigh frequency high voltage is a Tesla coil, possibly RF burns or heart failure if patients have pacemakerGet liability insurance and a very good lawyerSuggest that the project thème be changed.Design is impossible to comment on without complet schematic, Vcc, driver, transformers/ magnetic designBon courageJon

author: Ed.Kloonk
author_rank: Super Contributor
timestamp: August 20, 2022, 12:52:31 pm
content: Quote from: jonpaul on August 20, 2022, 12:50:16 pmI've heard of trying to eliminate the competition but I don't think that's what it means.

author: MarcusFunt
author_rank: Contributor
timestamp: August 20, 2022, 01:04:07 pm
content: My input voltage will be 12vdc from a commercial smps. but the voltage across the MOSFET is dependent on the resonant circuit formed by the primary coil and resonant capacitor. the resonant voltages and current are calculated by LTSPICE: 17A peak. 42vac peak. I will at max be drawing a few milliamps from the transformer.The MOSFETs will however only pass around 10A max.The gates will be getting 12v protected by Zener's and flyback diodes(probably not necessary)the inductance of my primary is going to be around 3-6microheny(very vague I know)I know my safety rules. I'm the only one going to be in contact with the device, and even then, I have plenty of safety mechanisms to ensure that no one is harmed
high voltage rail splitter ideas - Page 1
Forum section: electronics / projects

author: Smokey
author_rank: Super Contributor
timestamp: September 13, 2013, 10:54:52 pm
content: Anyone have any experience with high voltage rail splitters for creating a virtual common point? I'm talking about 150V (split to +/-75V), which in the grand scheme of things isn't that high, but it is higher than any single dedicated rail splitter IC can handle (that I am aware of at least).I probably need around 100mA referenced to that virtual midpoint.This site has some good info relating to low voltage audio stuff for some background.http://tangentsoft.net/elec/vgrounds.htmlIt looks like an active solution using a pair of transistors and biasing components is the way to go as long as I can get the heat out (which I shouldn't have a problem with with existing forced air cooling and heatsink).Thoughts, suggestions, rants welcome.

author: dannyf
author_rank: Super Contributor
timestamp: September 14, 2013, 12:06:11 am
content: QuoteThere is nothing special about those "rail splitters". If the load draws very little current, a resistive divider will work. If not, use a high voltage opamp - many audio power opamps can handle high voltage and I am sure you can find ones that fit your needs.

author: TerminalJack505
author_rank: Super Contributor
timestamp: September 14, 2013, 12:35:32 am
content: A unity gain, unipolar version of the circuit they're discussing inthis threadwould work as a high voltage rail splitter. The op amp's +/- 15V supply would have to be centered around your virtual ground. Then, to set the virtual ground output you'd just set the input at the halfway point.For more information regarding that circuit, you might look at theLT app note(that someone in that thread pointed out) where that circuit appears.

author: Smokey
author_rank: Super Contributor
timestamp: September 14, 2013, 01:38:47 am
content: Cool circuit. Ill give that a shot in the spice land and see if I can make that work.It looks like ill have to use a resistor divider to set the midpoint for the opamp reference and the +/-15 supply for the opamp but the rest of the current can come from the regulated output transistors.

author: TerminalJack505
author_rank: Super Contributor
timestamp: September 17, 2013, 09:16:01 am
content: For fun, I had a play around in the simulator with a couple of implementations of a 150V rail splitter.I don't know how well they'd actually work but I thought I'd share them in case they might give you some ideas.

author: dannyf
author_rank: Super Contributor
timestamp: September 17, 2013, 11:06:32 am
content: The zener is not really needed. For an open-loop buffer like that, transistors like SAP15P/N would be excellent.If you want a closed-loop solution, an opamp would work as well.Or to make it simpler, a high-powered audio amp can function as a rail splitter too.
High Voltage sampling with MUC - Page 1
Forum section: electronics / projects

author: anishkgt
author_rank: Frequent Contributor
timestamp: February 04, 2018, 08:34:41 pm
content: Hi All,I have a project where i need to sample the mains voltage into my MUC (an Arduino) and came up with this schematic of a precision rectifier, attached as CS.ExplanationIdea here is to detect when the secondary of the Transformer (MOT) is shorted. The LIVE LOAD here is a transformer (MOT) used for Spot welding, when shorted i can a voltage drop from 1.0vac to 0.5vac i just need to send this voltage to the ADC of an Arduino. So here for isolation i used a MOC3052 (https://www.digikey.com/product-detail/en/on-semiconductor/MOC3052SR2M/MOC3052SR2MCT-ND/1847083)optocoupler from fairchild. The LT1078 (https://www.digikey.com/product-detail/en/linear-technology-analog-devices/LT1078S8-PBF/LT1078S8-PBF-ND/889633)is a dual opamp precision rectifier from LT. C24 is a decoupling cap and C25 is to smooth the ac signal from LT. Then the second opamp is a buffer.WorkingThe the opto coupler would be triggered by the MUC via 220 \$\Omega\$resistor there by shoring the contact from the LIVE LOAD to the voltage divider and that goes on to send a dc voltage to the MUC. This happens when the MOT is powered.When the secondary is shorted now there would be a voltage drop at the primary contacts of the MOT and that would also be seen by the LT1078 and using code, the voltage drop would be sensed by the MUC then the the opto coupler would be disabled and the MOT would be powered for spot welding. Basically an Auto Sense, instead of having to press a button to weld.Then i noticed this schematic from TI, attached (http://www.ti.com/lit/an/sboa097b/sboa097b.pdf) page 4 Fig3 where a similar approach with less components. My basic requirement is to sense the voltage drop at the primary of the MOT.A silly question but am little confused as to which one to go with. I would really appreciate if somebody could advise/comment on the schematic. With the best of my knowledge and google i guess my schematic would work. I don't have the parts to test this out but before i do i just need some advise.
high voltage scope probe diy project - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: December 01, 2022, 09:35:50 pm
content: all details and all files are now freehttp://webx.dk/oz2cpu/hi-volt-probe/hi-volt-probe.htmenjoy

author: trobbins
author_rank: Frequent Contributor
timestamp: December 02, 2022, 03:24:00 am
content: Have you been able to check the frequency response?

author: lasmux
author_rank: Regular Contributor
timestamp: December 02, 2022, 09:24:06 am
content: Nice! You could put a trimmer cap in parallel with C6 to adjust for any parasitic capacitance in the circuit. Another thing to consider is the 3D printed case could have a finger guard to stop your hand slipping onto the DUT. I've seen a few HV probes with this.You really haven't taken any chances with your resistor chain! Lots of nice isolation. If you're measuring kV levels, have you checked that the creepages/clearances are okay?

author: oz2cpu
author_rank: Frequent Contributor
timestamp: December 02, 2022, 12:30:40 pm
content: no trimmer needed or wanted, i only want to use it together with my own scope,and it is only needed to be super fine tuned for very fast square signals,normally high voltage curves are rather slow on the edges, so in practice not a big deal.I have taken this one to 10kv a few times, just because it went lucky for me, is not the same thing as i recommend you do the same,5kV is the recommended max continues.no need to add finger hold back plastic, it is internal test equipment only to be used or made by people who knowhow hard 5kv kicks.but you are welcome to edit the STL files and reshare them, you are also welcome to get the fusion projectif you want to modify.

author: oz2cpu
author_rank: Frequent Contributor
timestamp: December 21, 2022, 09:33:55 am
content: here is another motivation to go DIYhttps://dk.farnell.com/tektronix/p6015a/probe-high-voltage-75mhz-1000x/dp/4352580look at the cost :-)
High Voltage supply for old CRT tube ? - Page 1
Forum section: electronics / projects

author: lordvader88
author_rank: Frequent Contributor
timestamp: March 16, 2018, 01:09:08 am
content: I have a RCA-WO33A CRT oscilloscope from he 1960s, and the transformer is busted, I've yet to take it apart, maybe its fixable. But if not, what are some ideas to make 600-700V at 10-20mA I think.I have 3-4 CRT TV PCBs with SMPS, and 1 from the 1970's, not sure if it's linear or switching kind. I have 2 microwave transformers that could maybe be rewound ? Or make a SMPS from scratch ? For now I don't want to spend much money, and I guess any suitable off the shelf transformer would be +$50 easy w/shipping

author: AutogolazzoJr
author_rank: Regular Contributor
timestamp: March 16, 2018, 01:54:18 am
content: I don't think a microwave transformer would get anywhere near the voltage you need. It would probably saturate. Perhaps an ebay flyback transformer?

author: Rog520
author_rank: Regular Contributor
timestamp: March 17, 2018, 12:28:42 am
content: You could probably find a cheap, used plate transformer (for vacuum tube equipment) at auction. Or find a transformer with a more common, lower voltage secondary and use a voltage multipler to get your required output. An SMPS in a scope is a bad idea unless it's specifically designed to be very low noise.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 17, 2018, 06:29:52 am
content: Some of the older radios (from the 1930s & maybe early '40s) used 285v a side " or even "385v a side" transformers with tube full wave rectifiers.The full voltages of these centre tapped secondaries are 570v & 770v respectively.Used with a bridge rectifier, these would give dc voltages of the order you require.1950s & 1960s transformers usually had secondaries of from 450 v to 480v total, but would work with a voltage multiplier.Unfortunately, these smaller transformers aren't as common in the USA as in Oz, as they used transformerless construction for most of their "mantel" radios.
High voltage transformer for 1kVdc 10mA supply - suggestions? - Page 1
Forum section: electronics / projects

author: Yansi
author_rank: Super Contributor
timestamp: April 21, 2022, 10:51:58 pm
content: Hello,for a project I need a 1kV regulated DC supply, that could deliver at least 5mA, better 10mA output current. For good repeatability of results, I would like to avoid winding diy transformers, so was looking into an option of repurposing a common CFL tube inverter transformers.These do have specs quite similar as to what I need, as the secondary voltage is usually specified in the range of like 1000 - 2000Vrms, so 1000Vdc after a rectifier would be definitely no problem. Power-wise, these transformers seems to also fit, as they usually are rated in the range of like 6 - 15W or sort of.However, I am having trouble finding a source of these transformers, where I could get a transformer including a full datasheet. (currently not in a mood of reverse engineering random Aliexpress transformers).How many pcs do I need? Say 10-20, likely not more.The only such transformer available in stock I could find with a spec sheet is this SGE2685-1G from Microsemi (or made for Microsemi? Datasheet attachedSGE2685-1G_transformer_CFL.pdf(162.35 kB - downloaded 204 times.)), which seems to be a spare for a LMT3210 TV set. These are available on Aliexpress. But just 7W, I would like to see bit more than that.Any ideas, where to look for these transformers, where one could locate a specsheet for them? Found some listed on Digikey (Coiltronics CTX410809-R), however 0 stock, deprecated, not manufactured. Or what other options of transformer to repurpose do I have for this task?Thanks for ideas.Y

author: moffy
author_rank: Super Contributor
timestamp: April 21, 2022, 11:23:28 pm
content: A simple flyback transformer would do the job, especially in that power range. CFL transformers are semiresonant and tend to be specifically to match the characteristics of the tube they are driving.

author: Marco
author_rank: Super Contributor
timestamp: April 21, 2022, 11:31:40 pm
content: CCFL inverters aremore easily available in module form. Also a lot of people have used them in the past for kV range power supplies.Of course CFL inverters are easily available from CFL

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 22, 2022, 12:04:59 am
content: That part seems rather small, with the #46 wire. Voltage should be about right.How about multipliers, could use a say 20W flyback in reverse? 12V in, 240V out, quadrupled or so.Tim
Higher capacity drop-in replacement for AT93C86? - Page 1
Forum section: electronics / projects

author: Unixon
author_rank: Frequent Contributor
timestamp: September 11, 2019, 06:12:29 pm
content: Hi, everyone.I'm kind of stuck with boards routed for 93C86, but I think I may need a higher capacity one.While browsing through catalogs I noticed that many ICs in active production use different pinouts.Can anybody tell off the cuff what EEPROM series are pinout compatible with AT93C86 (SO8 package, 3.3V operation) ?
Higher Melting Point Solder? - Page 1
Forum section: electronics / projects

author: ROBOT
author_rank: Contributor
timestamp: March 05, 2016, 11:21:12 pm
content: Anyone know where I can find some high melting point solder? I need it to be higher temp then the typical lead free.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: March 05, 2016, 11:28:38 pm
content: ebay

author: johansen
author_rank: Super Contributor
timestamp: March 05, 2016, 11:35:09 pm
content: Lead free plumbing solder melts at 450-460F95% Tin and 5% Antimony.

author: ROBOT
author_rank: Contributor
timestamp: March 06, 2016, 12:00:41 am
content: That's extremely low.. I'm looking for something above 270C

author: bmwnomad
author_rank: Contributor
timestamp: March 06, 2016, 12:18:17 am
content: How about some Sn05Pb95 (5% Tin, 95% Lead)? 301-314C melt range.http://www.kester.com/kester-content/uploads/2013/06/Alloy-Temperature-Chart-15Feb11.pdf

author: calexanian
author_rank: Super Contributor
timestamp: March 06, 2016, 02:43:56 am
content: Eventually you will get up into brazing alloy range. Typically you need a torch for them but I have seen some that flow at dull red heat. They are very common in auto body repair.

author: pelud
author_rank: Regular Contributor
timestamp: March 06, 2016, 03:46:47 am
content: Here is some multicore HMP series (SN5/PB93.5/AG1.5), and melts around 296-301C:http://www.digikey.com/product-detail/en/multicore/397952/82-140-ND/2498938

author: Whales
author_rank: Super Contributor
timestamp: March 06, 2016, 05:54:07 am
content: Straight lead.http://www.garelicksteel.com/pdfs/Melting_Points_of_Common_Metals.pdfBe wary with any solution: what you are soldering to will alloy with your solder. This may have a lower melting point. If possible, go for crimps.

author: PointyOintment
author_rank: Frequent Contributor
timestamp: March 06, 2016, 07:00:56 am
content: Here you go—pick one:https://en.wikipedia.org/wiki/Solder#Solder_alloys

author: blufeb95
author_rank: Newbie
timestamp: June 27, 2016, 03:22:05 am
content: don't know if you are still looking for higher melting point solder but you can score 1lb rolls of Kester 44(RA) or 285(RMA) Sn10Pb88Ag02 for quite cheaply, the Melting Range is 514-570°F / 268-299°C

author: HighVoltage
author_rank: Super Contributor
timestamp: June 27, 2016, 09:53:50 am
content: What is your target melting point?Felder in Germany will mix solder for custom specificationshttps://www.felder.de/
Higher sound pressure from a MAX98357A ?? - Page 1
Forum section: electronics / projects

author: espena
author_rank: Contributor
timestamp: September 11, 2023, 07:22:50 pm
content: I'm working on a IoT doorbell circuit:https://github.com/espena/dual-button-doorbell. It's a hobby project, and it works very well except for the speaker's sound pressure being a little bit on the low side. I'd wish for the output to be more audible.I went for the MAX98357A amplifier (U2 on the schematic) - assuming 3W output would do the trick. Still, the sound pressure is a bit too low using this 3W / 4ohm speaker:https://no.mouser.com/ProductDetail/DB-Unlimited/SW1000304-1?qs=DPoM0jnrROUOabiEq0xXSQ%3D%3D.The sound pressure is rated to 106 dBA (EDIT: at about 10 cm), I assumed that would suffice (wrong?). Don't know if my actual output is anywhere near that limit. If I increase the volume further, it seems to overdrive the amp/speaker.I've tried a 5W / 4ohm speaker as well. It resulted in better sound quality, but the sound pressure is of course pretty much the same.Having no experience with audio designs, I would love to hear from you: What would a proper design look like if it should replicate the audio output one usually expects from a loud doorbell? Another amplifier chip? More watts? Different kind of speaker? Additional circuitry? Other suggestions..?Ive seen some very small designs emitting impressive sound levels - so how do professional designers go about to get there?RegardsEspen

author: TimFox
author_rank: Super Contributor
timestamp: September 11, 2023, 07:43:40 pm
content: From a typical website list:100 dB(A) is a jet take-off at 305 meters.110 dB(A) is an auto horn at 1 meter, a normal sound level at a teen-age boomety-boom concert, and a typical threshold of pain in a human ear.Note that this reading is meaningless for a source unless you specify the distance from the source.How much sound does your dog need to bark at the door?

author: espena
author_rank: Contributor
timestamp: September 11, 2023, 07:50:43 pm
content: Thanks for pointing that out. I think the 106 dbA rating was specified at 10 cm distance

author: TimFox
author_rank: Super Contributor
timestamp: September 11, 2023, 07:55:50 pm
content: In my house, the distance between the doorbell sounder and my living-room couch is roughly 5 meters, so by inverse square law the sound level would be (5/0.1)2or 34 dB lower.Edit: corrected calculation

author: Zero999
author_rank: Super Contributor
timestamp: September 11, 2023, 08:01:54 pm
content: Use a more efficient speaker such as a reflex horn. It won't have such good sound quality but will produce a much louder sound, given the same power level in.

author: moffy
author_rank: Super Contributor
timestamp: September 11, 2023, 11:14:35 pm
content: With a speaker it is important to seal the back from the front so that air doesn't flow directly from front to back severely reducing its efficiency.
higher voltage reg - Page 1
Forum section: electronics / projects

author: p.larner
author_rank: Frequent Contributor
timestamp: March 06, 2024, 10:15:12 pm
content: is there something similar to the lm-723 that can stand a v+ of say 60-100v as oposed to the normal 40v?.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: March 06, 2024, 10:27:58 pm
content: Did you try looking at Digikey et al, and sorting for regulators > 60V ?Such a search returns 223 stocked choices.

author: mag_therm
author_rank: Frequent Contributor
timestamp: March 06, 2024, 10:33:54 pm
content: TL783
Highest REsistance Value for a low price manufacture - Page 1
Forum section: electronics / projects

author: sheitbrink
author_rank: Newbie
timestamp: January 21, 2015, 10:10:31 pm
content: Hi all,I was wondering what the highest value resistance you would be comfortable using on a board, given that their may be flux residue etc. My boss wants to build an oscillator with the lowest possible current, but I also know their is a good chance he will go for an inexpensive assembler. On top of all this the boards are going to be in cars, so the climate the boards are exposed to will run the full gambit of temperature, and humidity. I know flux residue will start conducting if they are exposed to allot of humidity. I was wondering if anyone had any resistance values I could stay well bellow to be sure to avoid any problems.Thanks

author: dannyf
author_rank: Super Contributor
timestamp: January 21, 2015, 10:37:23 pm
content: QuoteI know, Gohm or more: two open contacts on a pcb.
Highlighting nets in Eagle layout - Page 1
Forum section: electronics / projects

author: rithi3
author_rank: Newbie
timestamp: December 17, 2012, 08:28:42 am
content: Hi All, I'm a beginner in Eagle layout. I want to highlight nets in different colors. And also want to apply various design rules for different nets like different trace widths for different nets. Plz help me.

author: AndyC_772
author_rank: Super Contributor
timestamp: December 17, 2012, 08:40:43 am
content: Surely this stuff is in the manual, isn't it?

author: mamalala
author_rank: Unknown
timestamp: December 17, 2012, 05:37:31 pm
content: Quote from: AndyC_772 on December 17, 2012, 08:40:43 amLast time i checked, yes, it was all in the manual. But who know, may have changed during the past 10+ yearsGreetings,Chris

author: westfw
author_rank: Super Contributor
timestamp: December 18, 2012, 12:02:59 am
content: AFAIK, you can only have Nets in the "Nets" layer, so you're probably restricted to one color.You can vary the width manually, of course.Automatically changing the width of a net, or overlaying it with an additional line on another layer, based on network name, ought to be well within the capabilities of an eagle "User Language Program"
Highly accurate high voltage sensor circuit - Page 1
Forum section: electronics / projects

author: Stiive
author_rank: Newbie
timestamp: June 20, 2012, 06:20:17 am
content: Hi Guys,I'm new on this forum, I am from Melbourne and did my undergrad at Swinburne in Robotics & Mechatronics Engineering.I'm currently trying to design a 3-phase inverter for an induction motor.I am trying to work out what would be the most accurate method to sense my ~400V phase leads. The sample time will be 5uS, and has to be an instantaneous representation of the phase voltage, which will either be high (close to DC bus voltage ~400V +- voltage sag/ripple/switching losses), or low (close to GND). The voltages will be driven by square pulses 5uS in width, and can therefore can go from 0V -> 400V, 400V->0V (or stay roughly the same) in 5uS. The pulse may also last a few seconds in duration. Since I will probably only be able to get 1 reading of each phase in that 5uS, i was thinking of sampling just before the end of the pulse to give it time to settle.As these voltages are the most important part of my control code, what would be the most accurate method to sense these voltages with my 0-3.6V ADC? A transformer of known turns ratio? Voltage divider with ultra-precision foil resistors? Some precision IC chip?Currently my design uses foil resistors with an instrumentation amp as a unity buffer for my STM32F4 DSP chip. I'm also using a small cap to filter out some of the noise on my otherwise digital signal. As the phase voltage can go negative a few volts, and to cover noise, i have added in an offset of 312mV (~40V before 141:1 divider). I also need a quick clamping method to stop the instrumentation amp from going into overload (takes too long to recover), and to protect the ADC.I'm not sure about the zener on the input of the instrumentation amp, but i'm hoping i can find one which will have negligable (<pA) of leakage at 312mV. Is there a better clamp method I could use here?I'm going to get this made soon and want to try make sure its right the first time, as it will be costly (time&money) if its not.I think the filter cap needs to be a bit smaller, probably want a 5*RC<2.5uS to get me enough time to sample the signals. I also think i may need to decrease the output current of the voltage divider to give my clamps a bit more chance incase of large voltage spikes, but i don't want too small a current cus of any noise.Any thoughts/improvements/suggestions would be greatly appreciated.Stiive.
Highly Flexible Yet Durable Circuit Materials? - Page 1
Forum section: electronics / projects

author: d1ode
author_rank: Newbie
timestamp: May 23, 2018, 02:00:06 pm
content: I'm trying to put LEDs on a flexible PCB that is very durable. It needs to be able to be practically folded from any angle, with repeated flexing. I'm thinking of some sort of copper flex that would be laminated on both sides with some sort of polymer to increase the durability. It will need to handle 500mA and would be nice if it had some thermal conductivity to keep it cool.Any recommendations for the best flexible circuit board materials or manufacturer that would be most durable for repeated flexing?

author: Marco
author_rank: Super Contributor
timestamp: May 23, 2018, 03:47:51 pm
content: On a hunch I googled for polyurethane flexible PCB (polyurethane tends to be the best at so many things).Multiplecompaniesoffersolutionsbased on it for repeatable flexing.Actual folding might be pushing it though. Maybe they could put a conductive polymer on top of the copper so if a break occurs the polymer bridges it?

author: SiliconWizard
author_rank: Super Contributor
timestamp: May 23, 2018, 04:04:20 pm
content: Properly designing copper traces will also help tremendously (staggered traces, teardrops...)

author: jbb
author_rank: Super Contributor
timestamp: May 24, 2018, 12:14:50 am
content: Maybe a single layer 0.5 Oz flex PCB using polyimide base? This is used for inkjet printer stages, which whip back and forth for many many cycles. You could add stiffeners under the LEDs to reduce the stress concentration on the solder joints.
Highly integrated single cell Li* solution - Page 1
Forum section: electronics / projects

author: PeterFW
author_rank: Frequent Contributor
timestamp: May 17, 2016, 04:39:39 pm
content: Hello!Could not find one, so i am asking here. I have build my own lithium fuel gauge/charger/protection circuits that work well.But... id like to have something more compact to get more board space on a 2 layer board that is only populated on one side and has not too small features.Is there something compact out there that has protection, charging, current senseing and so forth all in one handy package?It should not be a BGA package, everything else is fine.Greetings,Peter

author: nctnico
author_rank: Super Contributor
timestamp: May 17, 2016, 04:41:54 pm
content: Texas Instruments and Linear have many battery management solutions. Did you already look at those manufacturers? With your requirements I'd start at Linear.

author: PeterFW
author_rank: Frequent Contributor
timestamp: May 17, 2016, 05:13:23 pm
content: Quote from: nctnico on May 17, 2016, 04:41:54 pmYes i ditThe most in one package i can get is a fuel gauge and protection in one ic, wich requires still two external mosfets and a seperate IC for the charging and power management.
Highly loaded (large fanout) 0-10V PWM output for HVAC  - Page 1
Forum section: electronics / projects

author: dmg
author_rank: Regular Contributor
timestamp: December 15, 2015, 02:53:56 pm
content: Hi,I need to design something that can drive groups of several PWM HVAC blowers (several ranging from 3 to 8 ). Each group of blowers need to be controlled by the same signal. There are blowers that accept 0-5V PWM input and blowers that accept 0-10V PWM input for speed control. All blowers in a system will be the same, I.E. either all work at 5V or all work at 10V, they won't be mixed.The PWM signal will be generated by a microcontroller. The problems I see are that:1- I don't know and can't find any spec on PWM frequency for typical blowers, I've been given datasheets of blowers but that information doesn't appear.2- The PWM output will be loaded with up to 8 blowers, control wiring can be long. I expect a relatively high capacitive load at this output due to the wires, and the control wiring won't be any sort of transmission line with predictable impedance.3 - I'm not very sure of what kind of protections would be required for this output. This is for an automotive application. I assume I should protect the output for ESD, have current limiting and protect it for short to 24V/Ground.I've seen examples doing this with open-collector/drain outputs with a pullup connected to the required PWM voltage, but I'm not sure if this scheme will be strong enough for such high fanout. I don't really know how long and what kind of cables will they use for the control signals (in fact that's arbitrary) so I can't predict how much load capacitance will they have. I've also thought about using automotive line drivers for high fanout applications like HEF4050B-Q100 plus a prior voltage translator, but this application is cost sensitive.Anyone can help me? I don't have experience with automotive stuff...
Highly selective band pass filter vs circulator? (IMD) - Page 1
Forum section: electronics / projects

author: Plasmateur
author_rank: Regular Contributor
timestamp: June 12, 2017, 02:29:18 am
content: I have a particular project in which I will be exciting two loop antennas within very close proximity to one another. The frequencies I expect to excite these antennas at are around 60MHz, and there will be a difference of about 1MHz in frequency with respect to one another.I expect there to be some kind of induction causing intermodulation distortion within these antennas. In order to minimize this I wanted to use a highly selective band pass filter on each antenna. However I don't believe such a filter commercially exists for such a narrow range between the two antennas.What if I were to use a circulator before each loop antenna? Would the induced signal from one antenna simply pass through the other port of the circulator, acting as a highly selective band pass filter?

author: David Hess
author_rank: Super Contributor
timestamp: June 12, 2017, 04:06:54 am
content: Most of the intermodulation will be produced in the amplifier so filtering will help. Circulators will help but do not have much directivity. 6 meter cavity filters would work if they can be tuned to the operating frequencies but they are pretty big. Helical resonators would work, are much smaller, and can be home made.

author: jbb
author_rank: Super Contributor
timestamp: June 12, 2017, 10:11:17 am
content: Can you adjust the locations of the 2 coils to reduce their coupling? That can get you 20 dB or more.Either twisting one 90 degrees or offset half a radius laterally. Depends on your requirements.

author: dmills
author_rank: Super Contributor
timestamp: June 12, 2017, 10:36:15 am
content: Very high Q 1/4 wave stub lines can be useful for this, think large bore heliax or copper water pipe with an air spaced cap at the top to tune the notch and the bottom shorted with a copper disk.You will really want access to a VNA to tune this sort of thing, but it used to be fairly standard on colocated band II PMR sites.73 Dan.
Hiland kit for dual/symmetric bench power supply? - Page 1
Forum section: electronics / projects

author: jaudo
author_rank: Newbie
timestamp: December 23, 2019, 12:17:23 am
content: Hi guys,I want an adjustable dual power supply both voltage and current to power op-amps.My goal is to have an electronics workbench and so far the only thing I lack is a dual power supply.Because standard dual bench power supplies are pretty expensive, I decided to buy a couple of Hiland kits linear adjustable power supply and a couple of 24 VAC transformers.I have mounted them and work. Now I would like to connect them in series to use them as a dual power supply.The only problem is that I don't know if with this kit the units will blow up.Below you can find the circuit diagram of the hiland kitAnd this is the link of the product. I'm sure more than one person here knows this kit.https://www.banggood.com/0-30V-2mA-3A-Adjustable-DC-Regulated-Power-Supply-Module-DIY-Kit-p-958308.html?rmmds=searchShould I be worried when connecting the supplies in series?Other products like the DPS and RD series don't allow connection in series or parallel, as stated by the designer.Does anybody know an affordable adjustable symmetric power supply?thanks in advance.

author: not1xor1
author_rank: Frequent Contributor
timestamp: December 24, 2019, 07:01:42 am
content: D11 should allow serial connection, but that circuit is really bad and unreliable.There are other threads dealing with that and suggesting possible improvements.Just use the search function of the forum.

author: Kleinstein
author_rank: Super Contributor
timestamp: December 26, 2019, 10:20:34 am
content: That kit has quite some weak points. The main problem with the circuit is that the OPs are operated way beyond there rated voltage. So there is a good chance they will blow up and the supply could than deliver full voltage or current. So even if it works now, it is not reliable.The easy to fix part is increasing R18, so that the maximum current is reduced to a safer 1-2 A level.The other point is using OPs that can stand the voltage - even if just 741s, like in the original version of this circuit.If used in series D11 should be powerful enough to carry the full current, possibly more. So it should be more like a 3 A diode like 1N5401.