hybridfree/eevblog-posts huggingface dataset:
HV (1500V) DC and AC power supply 500µA - Page 1
Forum section: electronics / projects

author: luky315
author_rank: Regular Contributor
timestamp: January 22, 2014, 09:15:29 am
content: I'm searching for ideas to generate a high voltage power supply (1500V) with an accurate (+-5%) 500µA current limit.My problem is that I need DC and AC currents. Is it better to design 2 separate units, one for AC and one for DC?
HV AC RMS current control... - Page 1
Forum section: electronics / projects

author: nickds1
author_rank: Contributor
timestamp: March 02, 2015, 04:44:15 pm
content: Hi...I'm looking for thoughts on how to control the RMS current through a device - the voltage across the device may be up to 1000VAC @ anything from 50Hz to 40kHz... I need to control the current in the range of 5mA - 100mA... +/- 10% or better. The DUT has a variable resistance over which I have no control - I just mustn't over-drive it...At the moment I have a small CT device sensing instantaneous current - an ISR in a small micro performs continual, rolling, RMS calculations (the waveform is not a good sinusoid) and can provide a feedback loop to control a FET or something similar to act as a variable resistive load. The uP is doing a bunch of other stuff too...The use of a current-limited PSU is not an option, unfortunately, as there will be a number of these devices in parallel and each much be managed independently.Ideas would be very welcome - I'll need some sort of galvanic isolation between the uP and the current-limiting-device.....Oh, and the application is pretty price-sensitive. Safety is a must. Cheap is very good tooMany thanks people!Cheers

author: nickds1
author_rank: Contributor
timestamp: March 02, 2015, 05:00:51 pm
content: Quote from: blueskull on March 02, 2015, 04:56:37 pmThanks for the reply - I'm already using an tinyAVR for this, indeed with a Hall-effect sensor - the real-time RMS bit is fine. However, I've not yet found a HV CS device that is in the range I need, i.e. sub 100mA. Most are 1A -> 10A or so, so my signal is very subject to noise and loss of accuracy.If anyone knows of a suitable integrated Hall device for sub 100mA with a decent galvanic rating, I'd be very interested !Thanks

author: dannyf
author_rank: Super Contributor
timestamp: March 02, 2015, 05:09:50 pm
content: QuoteA typical way to use a dc deivce to control an ac load is to put a rectifier around that dc device and float it. It can be easily done.It becomes a little bit more complicated if you have a closed loop control -> that means you need to sense the ac current -> one simple way to do it is to use a sense resistor + transformer to provide isolation.

author: nickds1
author_rank: Contributor
timestamp: March 02, 2015, 05:13:19 pm
content: As I mentioned, I am already using a Hall device to compute the RMS current in real-time.I'm familiar with using a full bridge plus a DC device for control, but its a complexity I feel just should not be necessary in this case... A decent HexFET in its linear region should do, but I'd like to explore other simple options...

author: VEGETA
author_rank: Super Contributor
timestamp: March 02, 2015, 05:35:12 pm
content: Use the IC called LTC1968 from Linear technology. It is RMS-to-DC converter, this helps you measure RMS signals. Use it according to your design.
HV Electrical Isolation - Page 1
Forum section: electronics / projects

author: rockbassist90
author_rank: Contributor
timestamp: July 01, 2014, 07:49:57 pm
content: I maybe overthinking this.I've designed controls for an assembly located in a 60kV environment where all electronics are at the same potential...but there is not yet software support, and we'd like to test positional accuracy of my servo loop by sending commands via serial comm (RS-232).To do this I would have to send commands via an ASCII terminal (laptop), all this is setup, but how can I safely isolate this DB9 at such a high voltage? Normally I would go with an optical isolater, but I have yet to find one with 70kV (10kV safety margin) isolation...Help please?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 01, 2014, 07:55:39 pm
content: Fibre optic or wireless

author: rockbassist90
author_rank: Contributor
timestamp: July 01, 2014, 08:03:49 pm
content: Do you have any suggest parts? The board uses an RJ12 connection.

author: Neilm
author_rank: Super Contributor
timestamp: July 01, 2014, 08:46:56 pm
content: I tend to use IrDA transceivers when communicating over a High potential barrier. Goes through plastic, easy to line up and dead simple to use.

author: rockbassist90
author_rank: Contributor
timestamp: July 02, 2014, 03:05:25 pm
content: Quote from: Neilm on July 01, 2014, 08:46:56 pmI'll look into it thank you!

author: qwaarjet
author_rank: Regular Contributor
timestamp: July 08, 2014, 03:39:53 am
content: I've used bluetooth to rs232 adapters before for like 600V isolation but there no reason the transceiver couldn't float at some higher voltage. However if you're getting arcs that might prevent the radio from being reliable, though 60kv arc would probably make anything without a faraday cage unreliable. In which case fiber optic would be better. IrDA would probably work if the environment allows safe use of it and you don't need a ton a bandwidth.

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: July 08, 2014, 03:51:11 am
content: just for weirdness sake - ultrasound can carry some bandwidth too thru air or as waves in solid insulationhttp://rbsfm.org/Downloads/Datasheet/LM/LM1812.PDF
HV generator integration - Page 1
Forum section: electronics / projects

author: sdouble
author_rank: Frequent Contributor
timestamp: February 07, 2018, 07:01:38 pm
content: Hi friends,I do play with (very) low noise charge integrator . My design is quite successful. My input referred noise is about 200 electrons, which is satisfactory.Now, I try to integrate a High voltage supply into my PCB.I need very low power (<1mW) and relatively high voltage (800 V) . Therefore, I went for an integrated EMCO (now XP power) module (P12P).In principle, the module is shielded again radiated noise.Since my design is highly noise sensitive, I wonder if I should take special care to the design :additional shield onto the provided one ? Slot in the ground plane ?all suggestions are highly welcome.
HV Generator - Page 1
Forum section: electronics / projects

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 21, 2014, 09:52:25 am
content: Going to be doing some highish voltage experiments soon, so I'm going to need something like this:Linear controlled Royer oscillator, typically runs around 60kHz. Adjustable 220-2070V output. Seems to be fairly low ripple, but there may be some instability under certain operating conditions (~half scale voltage, half to full load?), which I think has to do with either parasitic instability in the oscillator itself, or RFI pickup by the poor LM358.Don'cha just love how professional it makes things look, just having that damned yellow tape handy?Efficiency ranges from 10-20% at low voltages up to 60, maybe 70% at full voltage. Good for 5-10mA (varies by voltage), so yes,watch your fingersladies and gentlemen!At full output, I can draw a pretty reasonable "medium temperature" arc, using a 50k 5W (wirewound) resistor for current limiting.Tim

author: mathias
author_rank: Regular Contributor
timestamp: May 29, 2014, 04:07:43 pm
content: Nice! Very interesting to see how you've done it.If I'm reading your schematic right, it's linearly regulated, but limiting the current. Have you tried anything new with this converter, like switch mode regulation?

author: SeanB
author_rank: Super Contributor
timestamp: May 29, 2014, 04:13:18 pm
content: Even more professional if you use varnish to hold the tape down. Very nice build there.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 29, 2014, 07:53:04 pm
content: Thanks!Haven't screwed with it, no. It would be possible to drive from a buck, using a sufficiently large inductance (and a frequency either orthogonal to the oscillator's, or directly locked to an even harmonic -- dunno which would be better), in which case the circuit overall is exactly the same (including the regulator section), except you have a pulse width modulator and driver replacing the follower.The oscillator isn't the best approach for wide range; it gets squirrely at low settings and light loads, since even if the supply goes to cutoff, the gate bias remains (which is sufficient to develop a few hundred volts on its own).The Jim Williams solution might be to run it at full power, and pass or shunt filter with an Eimac 25T -- at even more cost to efficiency, but it sure would be simple and robust.Tim
HV load idea -- I`m looking for some criticizm - Page 1
Forum section: electronics / projects

author: 001
author_rank: Super Contributor
timestamp: July 07, 2018, 12:17:29 pm
content: I`m going to buid DC load for 0-400V 0-2АThe idea is to connect MOSFET and common light bulb(s) serialThe benefits of light bulb is low cost and compact size (instead of power resistors)But I knew what impedance of light bulb is not constantIs it problem?Any opinions?

author: Cliff Matthews
author_rank: Unknown
timestamp: July 07, 2018, 12:48:52 pm
content: That's 800 watts max.. no small project if you expect fine linearity. Tungsten filament bulbs are low resistance when cold, so at lower currents your MOSFET will have to dump most of the heat. Maybe 8 in parallel (each with 2 60-watt series connected bulbs, resistor divider and op amp feedback loop)? Just guessing..*edit: Have you given thought to NiChrome heater element configurations? (such as those found in common hair dryers)

author: daqq
author_rank: Super Contributor
timestamp: July 07, 2018, 02:54:49 pm
content: If you're going for cheap, as was suggested look into heater appliances, kettles, immersion water heaters, electric water heater elements, that sort of thing. They are generally pretty rugged. Also, they are by definition easy to get heat out of, especially things like electric water heater elements.QuoteWell, yeah, but you still have to deal with 800W of heat. Only a VERY small portion will end up being light, the rest is heat. The same goes for any kind of load. 800W is a LOT of heat to deal with.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: July 07, 2018, 03:01:08 pm
content: Quote from: daqq on July 07, 2018, 02:54:49 pmThe light ends up as heat also.
HV MOSFET vs. HV BJT for Nixie cathode driving - Page 1
Forum section: electronics / projects

author: shadewind
author_rank: Frequent Contributor
timestamp: April 24, 2011, 04:24:43 pm
content: I designed a little board which uses a 16 output decoder (74HC154) driving a number of MMBTA42 high voltage NPN transistors (that's the SMT version of MPSA42) which drives the cathodes on a Nixie tube. The reason I chose the MMBTA42 is that everyone doing Nixie stuff seems to be using it (or rather the MPSA42, but you get what I mean).This got me thinking... is there any particular reason why it's better to use this rather than a HV MOSFET? Wouldn't that also eliminate the need for a base/gate resistor or is that needed anyway to limit the current spike when switching? HV MOSFETs have high Rds(on) but I doubt that really matters in this case since it is still very small compared to the anode resistor for the Nixie.
HV piezo supply recomendation - Page 1
Forum section: electronics / projects

author: grouchobyte
author_rank: Regular Contributor
timestamp: October 11, 2016, 01:34:03 am
content: One of my consulting clients needs a very compact and very low current supply for a piezo-driven optical scanner in a medical probe. We need about 150 volts and less than 2 mA from a DC source like under 12 volts. The formfactor must be small and this solution is too largehttp://www.xppower.com/Portals/0/pdfs/SF_AG_Series.pdf?ver=2016-07-22-085731-773I can design a cockcroft multiplier but I am not sure I can get the total volume solution any lowerAny ideas?@grouchobyte

author: Someone
author_rank: Super Contributor
timestamp: October 11, 2016, 01:54:14 am
content: Before looking at the link I imagined how small I could squeeze such a specification, not much smaller than they have. Anything under 400V is usually easier and can be done in a direct boost if you don't mind the noise or use a tinycoupled inductor, and while getting to half their size is possible, a quarter would be very hard.

author: grouchobyte
author_rank: Regular Contributor
timestamp: October 11, 2016, 05:58:00 am
content: Quote from: evb149 on October 11, 2016, 03:43:02 amevb149Thanks for your posts. Seems you've been down this path before. The project I am doing consulting work on is confidential and I have signed an NDA on it so I am sworn to secrecy since its a patented medical device we are trying to commercialize and miniaturize. I will review some of these suggestions and possible try some of them out in the lab.@grouchobyte

author: eliocor
author_rank: Unknown
timestamp: October 11, 2016, 11:17:54 am
content: Maybe you can use the following transformers (1:10):TDK ATB3225: they are rather small.They are even not too expensive:http://www.digikey.com/product-detail/en/tdk-corporation/ATB322524-0110/445-8636-1-ND/3008154followed by 1 stage multiplier the complete power supply should not require too much space.

author: daqq
author_rank: Super Contributor
timestamp: October 11, 2016, 01:28:45 pm
content: You can get really small with a boost DC DC converter, perhaps with an external transistor.See the UC3845B (http://www.st.com/content/ccc/resource/technical/document/datasheet/b6/e8/cc/ba/4f/cd/42/9b/CD00000966.pdf/files/CD00000966.pdf/jcr:content/translations/en.CD00000966.pdf) - I used it for the same purpose recently - get +250V @ 6W from a +12V DC source. I just added an external transistor, caps, inductor, diode and the proper feedback divider. There are other, similar ones out there.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: October 11, 2016, 01:40:01 pm
content: You'll probably struggle to get much smaller than a commercial DC-DC unless your output requirement is a lot lower than the nearest model.Look at (magnetics for) supplies for electroluminescent displays which are in a similar ballpark voltage-wise.Small DC-DCs tent to use high frequencies ( low MHz) but this gets less practical at higher voltages due to capacitive losses.
HV9910BLG-G replacement? - Page 1
Forum section: electronics / projects

author: xavier60
author_rank: Super Contributor
timestamp: September 14, 2021, 07:24:41 am
content: The Microchip HV9910BLG-G is out of stock at all main distributers with new stock not being expected until mid next year.I bought some IXYS MXHV9910BE parts expecting them to be a drop in replacement but they are not.Is anyone else in the same situation and has found a suitable replacement for the Microchip part?

author: DeanA
author_rank: Regular Contributor
timestamp: September 14, 2021, 10:30:04 am
content: Sorry, can't help, we use (a lot) of the HV9931, if that becomes unobtainium we will be in real trouble.

author: xavier60
author_rank: Super Contributor
timestamp: September 14, 2021, 10:39:17 am
content: Quote from: DeanA on September 14, 2021, 10:30:04 amThe good news is you might get yours earlier next year.https://au.mouser.com/ProductDetail/Microchip-Technology/HV9931LG-G?qs=%2Fha2pyFaduhkyVs2j4g%2FV3a%2FRSJM%252BA2Pe9Ao33A4VG8%3D

author: DeanA
author_rank: Regular Contributor
timestamp: September 15, 2021, 12:40:09 am
content: Quote from: xavier60 on September 14, 2021, 10:39:17 amBad news is I warned purchasing about this possible shortage back in April when there was still stock around and they did nothing about it.

author: xavier60
author_rank: Super Contributor
timestamp: September 15, 2021, 01:01:24 am
content: "An Arrow company"https://www.verical.com/pd/microchip-technology-led-driver-HV9931LG-G-1221478?utm_medium=aggregator&utm_source=findchips&utm_campaign=verical_2021&utm_content=bnl_1

author: xavier60
author_rank: Super Contributor
timestamp: September 15, 2021, 01:29:16 am
content: Alsohttps://www.tme.eu/en/details/hv9931lg-g/led-drivers/microchip-supertex/?utm_campaign=compare-2021-09&utm_medium=cpc&utm_source=findchips.com

author: xavier60
author_rank: Super Contributor
timestamp: September 17, 2021, 09:05:29 am
content: This is interesting. While searching for my part, I discovered the HV9961.It functions the same as the HV9910 excepting that it senses and regulates average inductor current rather than peak current.It will be useful for LED current drivers where the load voltage isn't closely known.http://ww1.microchip.com/downloads/en/DeviceDoc/20005588A.pdfExtra: I bought a few on Aliexpress to experiment with. They appear to be genuine Microchip parts and work according to the data sheet claims. As a replacement for the HV9910B, it needs about 1.5V on the LD pin and RT needs to be tied to ground. It operates in constant-off-time mode only.
HV9910C duty cycle - Page 1
Forum section: electronics / projects

author: 22
author_rank: Contributor
timestamp: June 13, 2017, 02:01:56 pm
content: Here is a datasheet for HV9910Chttp://ww1.microchip.com/downloads/en/DeviceDoc/20005323A.pdf.Can anyone tell if that IC is capable of 100% duty cycle without any hidden limitations ? The ic will be working in constant off-time operation. I know there are similar IC from the same manufacturer, but they all have limit to 80-93% duty cycle. Thanks.

author: RobK_NL
author_rank: Frequent Contributor
timestamp: June 13, 2017, 07:34:06 pm
content: At least the original Supertex datasheet (from 2004!) states 100% as maximum dutycycle.

author: MagicSmoker
author_rank: Super Contributor
timestamp: June 13, 2017, 08:01:15 pm
content: Quote from: 22 on June 13, 2017, 02:01:56 pmI don't need to look at the datasheet to answer your question: no, you can't reach 100% duty cycle if there is a constant, non-zero off-time per switching cycle. That should be self-evident.

author: RobK_NL
author_rank: Frequent Contributor
timestamp: June 13, 2017, 08:16:25 pm
content: Quote from: MagicSmoker on June 13, 2017, 08:01:15 pmBut if the current through the LED(s) does not reach the threshold value, there will be no switching cycle ...

author: 22
author_rank: Contributor
timestamp: June 13, 2017, 10:55:57 pm
content: Quote from: RobK_NL on June 13, 2017, 07:34:06 pmThanks!
HVAC/PLC Universal Input Design - Page 1
Forum section: electronics / projects

author: StuntMonkeh
author_rank: Newbie
timestamp: January 10, 2014, 03:59:22 pm
content: I have been working on a universal input design to be used with an MCU from some existing schematics I found.I was lucky enough to find the resistor network to setup the input in a datasheet from one controls manufacturer but I have been trying to figure out what other components were required to make it resistant to the expected voltages without killing the MCU ADC input.Is what I have done so far correct, can anyone suggest any improvements upon this?

author: SeanB
author_rank: Super Contributor
timestamp: January 10, 2014, 04:14:52 pm
content: Other than the LM358 being the wrong choice with the supply voltage you have all else will work and survive pretty much anything up to mains being applied ( except in current mode where the resistor will die a fast death) to the input.

author: StuntMonkeh
author_rank: Newbie
timestamp: January 10, 2014, 04:37:45 pm
content: Yes input to expect up to 24vAC no higher.I wasn't sure what type of opamp, I need to really investigate that part further although the datasheets I can find indicate most LM358's are 3.0v to 30v.Can anyone point me in the right direction of how to choose correct opamp selection.

author: orion242
author_rank: Unknown
timestamp: January 10, 2014, 04:38:52 pm
content: That diagram looks identical to the inputs on the controllers I use.What brand did you hock that from?

author: SeanB
author_rank: Super Contributor
timestamp: January 10, 2014, 06:07:15 pm
content: LM358 may be rated from 3V but at 3V it can barely do 100mv in the middle. You need a rail to rail input and output opamp to work off 3V properly.

author: StuntMonkeh
author_rank: Newbie
timestamp: January 10, 2014, 09:27:34 pm
content: Am I on the right track if I read this?http://www.ti.com/lit/an/sloa098/sloa098.pdf
HVDC Capacitor Charger Help - Page 1
Forum section: electronics / projects

author: Goature
author_rank: Contributor
timestamp: June 06, 2014, 07:48:22 pm
content: Hello! I'm working on a HVDC capacitor charger. I've made it work, and it charges the capacitors to around 400V. This is the circuit:... and here's my problem:When i discharge the capacitors over a large inductor (you can probably figure out what i'm doing here) different parts of the circuit fails; specially the 555 and the mosfet. I've concluded that it's probably caused by a large negative ripple the second the inductor is discharging. How can i protect my circuit from this ripple, and still get it to charge as it sould? (U2 and U3 are connected to the capacitors)Bonus round: Do you have other improvements for the circuit?Thanks!

author: johansen
author_rank: Super Contributor
timestamp: June 06, 2014, 07:55:57 pm
content: you have to disconnect the capacitor from the charging circuit.when you discharge a capacitor into an inductor, the energy is conserved, the current will continue to flow through the boost diode and the mosfet body diode.most likely neither of which can handle the current, and the leakage inductance of the circuitry means some of that voltage will blow up everything else as well.

author: Goature
author_rank: Contributor
timestamp: June 06, 2014, 08:01:47 pm
content: Quote from: johansen on June 06, 2014, 07:55:57 pmThat's true! I forgot to mention that the diode also blows up often. I guess a hefty relay of some sort would help? Maybe a smaller contactor? Got to look into that!

author: tautech
author_rank: Super Contributor
timestamp: June 06, 2014, 08:08:10 pm
content: Glaring omissions to manage the Back EMF are:SnubberDiode ratings ?Series diode before L1IC de-coupling capEDITAnd R3 4R7R4 1K

author: Goature
author_rank: Contributor
timestamp: June 06, 2014, 08:39:57 pm
content: Quote from: tautech on June 06, 2014, 08:08:10 pmD1 is a MUR1560 (http://www.onsemi.com/pub_link/Collateral/MUR1520-D.PDF):VRRM: 600VAverage current: 15AD2 is a simple 1N4007 (1000V, 1A)Thanks for the suggestions!

author: max_torque
author_rank: Super Contributor
timestamp: June 06, 2014, 09:04:54 pm
content: For anything like this^^ you can't beat a proper physical "disconnect". Use a relay with suitable rating (and contact gap!) to break both the +ve and ground lines to the HVDC cap and firing circuit

author: doktor pyta
author_rank: Frequent Contributor
timestamp: June 06, 2014, 09:37:56 pm
content: HiIf You want to obtain high efficiency it's better to have current- control SMPS IC.Similar thread was discussed few years ago on a Polish forum.Below link.http://www.elektroda.pl/rtvforum/topic556770-0.htmlThe guys are helping each other and the final schematic is the "schemat4.gif".You should use Google translator, but basically schematics are universal language. Like music...

author: Goature
author_rank: Contributor
timestamp: June 09, 2014, 07:35:04 pm
content: Quote from: doktor pyta on June 06, 2014, 09:37:56 pmVery interessting! I'm going to have a look at that!
HVDC power supply for tube circuits NEED ADVICE - Page 1
Forum section: electronics / projects

author: Beauregard42
author_rank: Newbie
timestamp: April 24, 2024, 02:50:10 pm
content: Do you guys have any good designs for high-voltage DC power supplies (up to 500 volts, at 1 amp. I might need to drive at least 8-10 tubes in certain circuits)I ain't rich, nor do I live near any electronics supply stores, which means I have to scavenge for components, or make my own components. (I know how to make capacitors, both electrolytic and non-polarized, and everyone can wind coils if they have hands)I have about 80 vacuum tubes to play with, so I'm good on that front. Not really any sockets, though, so I might have to do wire-wrap for that. I also used up all my solder six months ago hehe.Thanks.

author: tmd63
author_rank: Contributor
timestamp: April 24, 2024, 05:56:19 pm
content: Have you tried the old american radio magazines website?https://www.americanradiohistory.com/ETI_Magazine.htmhttps://www.americanradiohistory.com/Practical_Electronics.htmhttps://www.americanradiohistory.com/Everyday_Electronics.htmSome Useful articles there dating from way back when
HW-585 fan controller - Page 1
Forum section: electronics / projects

author: tony359
author_rank: Frequent Contributor
timestamp: September 06, 2022, 07:26:11 pm
content: Hello all,I have a cheap fan controller board which sets the speed of the fan based on the temperature. Temperature delta are set and can be chosen via dip-switch. I would like to change the range of intervention as I need something more 25-35 degrees and the lowest range I can select is 35-45.The circuit has been reverse-engineered here:https://www.electroschematics.com/fan-speed-controller/There is an NTC sensor which is wired like the attached.I found that replacing those two 103 (10K) resistors with a 12K one, the intervention range lowers so that the fan starts speeding up slightly at room temperature. Is that the correct approach? Can I add a resistor in series/parallel to the NTC instead to achieve the same thing? Maybe a variable one?Thank you!
HX711 - Page 1
Forum section: electronics / projects

author: alizare368
author_rank: Regular Contributor
timestamp: December 09, 2018, 02:03:55 pm
content: HiI designed a board for weight measurement with load cell sensor and using HX711 for high accuracy.How can I calibrate it for milligram(mg)?the output of ADC(HX711) and C CODE contract in txt files.How can I stable the output?How can I implementation it with order 10 FIR lowpass filter?

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 09, 2018, 03:14:00 pm
content: don not triple post, its a violation here the mod may ban you.you can edit your post in the first thread (with people replying below) to add your attachment,no need for reply here to avoid confusion and abberation of informations...continue here...https://www.eevblog.com/forum/microcontrollers/hx711/?topicseen
HX711 + DRV8833 = cheap ac bridge measurements? - Page 1
Forum section: electronics / projects

author: wilhe_jo
author_rank: Regular Contributor
timestamp: April 16, 2018, 10:20:16 pm
content: Hi there,anyone already tried this? I need a dirt cheap solution for a weight scale with as good temp-stability as possible (for that little money).The HX711 is dirt cheap, as is the DRV8833 ... so why not combining both???I mean you'd just need to use the output of the v-reg of the HX711 as Vm (motor supply) of the DRV8833 and do some magic in the uC controlling everything...Anyone any thoughts about that???73
Hy-link HLK-PM01 Non-isolated SMPS - Page 1
Forum section: electronics / projects

author: Glion
author_rank: Newbie
timestamp: January 28, 2023, 12:29:45 am
content: Hi,I'm working on a circuit that has a power meter to a MCU. The power meter chip ATM90E32 measures mains voltage directly (via a resistive divider). This is shown in the application notes for the device on page 4 (link below).I'm going to power the circuit via a SMPS the HLK-PM01.What is the correct way to handle the Ground (this is the circuit ground) and Natural connections?- Ground and Natural could be joined this is the easy option.- The ATM90E32 has both analog and digital grounds so this gives the option to have them separate.https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ApplicationNotes/ApplicationNotes/Atmel-46103-SE-M90E32AS-ApplicationNote.pdf

author: moffy
author_rank: Super Contributor
timestamp: January 28, 2023, 04:00:20 am
content: You should not join ground and neutral in your device, it might have unintended consequences. That should only be done at the supply board if required. Since you are measuring between active and neutral, neutral becomes your ground and this is shown on page 4 of the App Note where UN(Voltage Sampling) is shown as the ground.
HY50-P/SP1 current transducer - Page 1
Forum section: electronics / projects

author: gaminn
author_rank: Frequent Contributor
timestamp: May 23, 2024, 11:11:59 am
content: Hi,I'm repairing an inverter and it has HY50-P/SP1 50A 5V single supply current transducer inside which seems to be broken as its output at 0A current is 0 V (should be 2 V according tohttps://www.lem.com/sites/default/files/products_datasheets/hy_10__50-p_sp1.pdf) and the output doesn't change when current flows via primary. Anybody any idea where to buy this transducer or where to get a replacement? Unfortunately it looks like this is already discontinued part.

author: moffy
author_rank: Super Contributor
timestamp: May 23, 2024, 11:29:02 am
content: They have stock at Digikey:https://www.digikey.com.au/en/products/filter/current-sensors/525?s=N4IgTCBcDaIBYE8CsAGADiAugXyA

author: gaminn
author_rank: Frequent Contributor
timestamp: May 23, 2024, 11:31:07 am
content: No, unfortunately they don't have it in stock. It is probably HY50-P you see they have in stock which has different pinout and supply voltage.

author: moffy
author_rank: Super Contributor
timestamp: May 23, 2024, 12:47:51 pm
content: Second times the charm, 2 in stock:https://fastron.com.au/products/hy-50-p-sp1

author: gaminn
author_rank: Frequent Contributor
timestamp: May 23, 2024, 01:08:23 pm
content: Thanks a lot but unfortunately, I need multiple pieces and also the price is completely out of my budget.The nearest replacement I found is pin incompatible ACS772ECB-200B, 10mV/A sensitivity. Unfortunately the zero of the output is at 2.5 V, not at 2 V as for HY50-P/SP1. So it will need an adapter and some circuitry around to have 2V zero of the output.
Hybrid low noise amplifier - Page 1
Forum section: electronics / projects

author: edgaras006
author_rank: Contributor
timestamp: February 11, 2025, 01:07:35 pm
content: Hi,In the ADA4807-2 datasheet I found very interesting schematic. Figure 70 fromhttps://eu.mouser.com/datasheet/2/609/ADA4807_1_4807_2_4807_4-2955808.pdfdatasheet.How are qn0, qn1 biased? Shouldn't qn1 have base collector shorted?As I understand the intention was to bias qn0 at 5mA. Opamp between jfets sees -0.5V between its inputs. With gain of -6, output is 3V.What about jfets? They saturate at -1Vgs, so how does this thing work.Thank you.

author: jwet
author_rank: Frequent Contributor
timestamp: February 11, 2025, 01:57:31 pm
content: That is real exotica. Its pretty tricky. I'll give it a stab by inspection. Maybe we can iterate. Don't laugh at my mistakes.The ADR510 is 1v, so the R7 drop is held at 1v. Its bottom is at -5v so the emitter of qn0 is at -4v, current is 1/200 = 5 mA. So that part is a 5 mA sink with a compliance of -4v.The left amp is a servo that is looking at the voltage drop across the 100 ohms. It controls the drains to the matched FET's. (there is also trim at op). Assuming V- and V+ are centered at ground, the sources will be at about 1v. The servo will push on the drains to maintain its inputs at zero differential. This will be satisfied when IR2 = IR3- they both come back to qn0 collector. Since R3/R2 is 10x, this maintains this current ratio of 11x. If I total is 5 mA, approx 4.5 mA flows through R2 and .45 ma flows through R3. This .45v gets gained up by R4 (transimpedance almost) and keeps something like 2v on the output of the servo. It really doesn't care what this voltage is as long as the 10/1 and I total is satisfied.Wow- isn't analog design fun.! I'd have to think more why the designer went through all this- I think its just a nice voltage limited current source that gives a high impedance current source without the use of any large resistances to keep noise low. That must be an electrometer front end or something.I think also, not shown is going to be some overall feedback that wraps around the whole circuit including amp2 to maintain V-/V+ at 0V.Thanks for the diversion.NB- poked around on Linear Systems site- the FET Supplier. They have some app notes written by Bob Cordell- a legendary preamp designer. That's a $10 transistor!
Hybrid power supply whith switching pre regulator - Page 1
Forum section: electronics / projects

author: harchom23
author_rank: Newbie
timestamp: January 09, 2016, 06:39:59 pm
content: I designing my new power supply, i going to use switching preregulator (step-down) whit TL494. in principle I start form datasheet schematic and use diferent voltage control and diferent transistor switching (FET). I can calculate inductance for output chock, for constant voltage, but I need adjustable output (aprox. 80V-5V)... then I need to calculate whit maximum out voltage? or middle?this is my first post, thank you for soon answer

author: Marco
author_rank: Super Contributor
timestamp: January 09, 2016, 08:00:19 pm
content: I'd start with two COTS 48V switching power supplies, that way you don't have to deal with mains. Costs you efficiency, but 80-5V is hard to do efficiently without complexity any way.

author: harchom23
author_rank: Newbie
timestamp: January 09, 2016, 09:29:21 pm
content: yes, supply voltage is 96Vdc from power transformer, OK, then call it buck...efficiency is not problem...ok, i calculated it for d=50% and try tu build prototype...
Hydra Meter - Open Source Electronics Multimeter - Page 1
Forum section: electronics / projects

author: EEVblog
author_rank: Unknown
timestamp: December 26, 2024, 09:22:31 pm
content: Open source multimeter project:

author: rteodor
author_rank: Frequent Contributor
timestamp: December 26, 2024, 09:42:16 pm
content: Also mentioned here:https://www.eevblog.com/forum/oshw/hydra-meter/

author: EEVblog
author_rank: Unknown
timestamp: December 26, 2024, 09:48:09 pm
content: Quote from: rteodor on December 26, 2024, 09:42:16 pmOops. Will probably get more traction in the test equipment section here.

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 26, 2024, 09:48:18 pm
content: I'll put a link to the repo here:https://github.com/jduffy105/HydraMeter_0.4(it's also in the other thread)

author: coppercone2
author_rank: Super Contributor
timestamp: December 27, 2024, 12:41:25 am
content: I did not look through schematics and designs yet but I think a good feature would be to add a solder pad to attach a 'finger' to, so if you make it, and use some kind of shield like paint, tape, plating or just metal panel, it can ground to a good point on the PCB. It might get rid of issues that are likely to arise from walki talki and stuff like that. Its a zero cost feature (for the PCB) that can potentially save some users alot of trouble.Most meters at least have a spring finger and a small metal sheet in them to act as a partial shield on the back cover.fluke often has some version of thishttps://lh4.googleusercontent.com/-7XFkS10TFfY/VE7yZJFR3zI/AAAAAAAAAPw/Yq-aHcAMank/w762-h572-no/04.JPGThey will just have a springy metal piece soldered to the PCB that touches it when you close it uphttps://www.eevblog.com/forum/testgear/fluke-179-teardown-photos/it was added to some meter because they were acting funny around VHF. I suspect it might be a common problem for similar class of electronics.
hydrogen fuel cell voltage output characteristics - Page 1
Forum section: electronics / projects

author: sarepairman2
author_rank: Frequent Contributor
timestamp: January 30, 2016, 08:59:47 pm
content: So i saw mike tear down a hydrogen fuel cell cellphone charger and rant about how useless it is.how does the voltage output of these devices look like in terms of things like 1/f noise, etc? i would buy one if it has some weird esoteric property that would make it superior to a battery powered device (assuming you use a linear regulator instead of whatever switching thing it has in it)the engineering that went behind it is too nice, perhaps it has a use in the laboratory! or as a circuit element.be creative, please dont turn this thread into a rant. i am just looking to find an alternative use for someones well designed if not misguided systemi really want this thing to somehow make a LTZ1000 better so I can build the worlds most ridiculous piece of test equipment

author: MagicSmoker
author_rank: Super Contributor
timestamp: January 30, 2016, 10:17:31 pm
content: Quote from: sarepairman2 on January 30, 2016, 08:59:47 pmThey deliver pure DC much the same as a solar cell or battery. One caveat is that fuel cells really don't like reflected ripple nor a rapidly changing load (the definition of "rapidly" varies greatly here, but assume a rate of change in the range of 1% per second).

author: sarepairman2
author_rank: Frequent Contributor
timestamp: January 31, 2016, 01:00:02 am
content: yes but I am interested in low level behavior. different batteries have slightly different output spectrums.granted they might be all lower then regulation circuitry. i just really want to figure out some logical reason to integrate a fuel cell into a circuit as a power source for a weird electrical reason.the more wacky and more engineering disciplines a circuit has the more interesting it is
Hysteresis For A Window Comparator - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: March 10, 2021, 10:32:26 am
content: When out=HIGH, want lower comparator's '-' input (TripL) to go lower. This means the output transistor is 'OFF' so the pull-up has a chance of working.But taking TripL low ALSO pulls TripH low. This could cause a valid input near to TripH to appear invalid, causing the upper comparator's transistor to turn on.The output is effectively "wired-NOR", with 00-->High for valid input inside the thresholds.TripL < U ---> Lower comparator sees valid input"OR"U < TripH ---> Upper comparator sees valid inputSo if out=HIGH, we want hyteresis to pull TripH 'upwards', and TripL to move downwards.Is there a neat, simple solution?

author: Zero999
author_rank: Super Contributor
timestamp: March 10, 2021, 11:54:03 am
content: https://www.eevblog.com/forum/beginners/window-comparator-hysteresis/msg575691/#msg575691

author: 741
author_rank: Frequent Contributor
timestamp: March 10, 2021, 01:18:32 pm
content: That is interesting - but I think it assumes the existence of nice low-impedance voltage references?It looks as if VRefh must be 'solid' in the face of varying feedback via Rf1. Or, possibly one could calculate the effect and allow for it.So long as I do not need 2x op-amp buffers to supply references.

author: Zero999
author_rank: Super Contributor
timestamp: March 10, 2021, 01:44:28 pm
content: Quote from: 741 on March 10, 2021, 01:18:32 pmHow much current can the references source and sink?Isink = (Vcc-VrefH)/(R1+Rf1+R2)Isource = VrefH/(R2+Rf1)Make Rf1 and R2 as big as you can and it won't be an issue.
I am building a ATX switching power supply auxiliary power supply board  - Page 1
Forum section: electronics / projects

author: sam_sam_sam
author_rank: Contributor
timestamp: February 27, 2021, 01:01:53 am
content: I have built a ATX switching power supply auxiliary power supply board input voltage is about 75 volts with no loadWith a load of about 4 amps the output voltage is about 50 voltsBut I have run into a brick wall with this project I am in need of a switching regulator that input voltage has to above 80 volts and can handle a current of about 4 to 5 amp would be nice if possibleI have looked for one but I can only find ones with the highest input voltage about 48 volts and this will not work correctly for what I want to do with itI am hoping that someone on this forum can help me out with project and the issue request that I have

author: sam_sam_sam
author_rank: Contributor
timestamp: February 27, 2021, 01:09:39 am
content: UpdateI have use another post for the other pictures

author: sam_sam_sam
author_rank: Contributor
timestamp: February 28, 2021, 06:31:37 pm
content: UpdateWould this workDC-DC Buck Converter Step-Down Power Supply Module in 20-70V Out 2.5-58V 30Ahttps://www.ebay.com/itm/DC-DC-Buck-Converter-Step-Down-Power-Supply-Module-in-20-70V-Out-2-5-58V-30A/124534306896?hash=item1cfed2b850:g:ecsAAOSwCi9gBloKBut unfortunately it to me is over kill in the amperage I am only looking for something that is about 5 or so

author: ajb
author_rank: Super Contributor
timestamp: March 01, 2021, 04:03:04 pm
content: Your link doesn't work. Looks like there is a bit chopped out of the middle?It's not clear what you're trying to do. Are you tapping into an ATX power supply and attempting to graft on an additional power rail? So you need a converter that can handle 80V input, and 4-5A, but what output voltage? And is that 4-5A the output current, or the max input current you can consume? Are you looking for a converter module, or an IC you can build a circuit around, or ?

author: sam_sam_sam
author_rank: Contributor
timestamp: March 02, 2021, 12:47:31 am
content: Quote from: ajb on March 01, 2021, 04:03:04 pm
i am looking a kit .. - Page 1
Forum section: electronics / projects

author: reeraslan
author_rank: Newbie
timestamp: June 27, 2011, 09:31:55 am
content: hi i am looking a kit that device is a Transceivering video and audio. Could you suggest anything about that device ?

author: sacherjj
author_rank: Frequent Contributor
timestamp: June 27, 2011, 04:32:48 pm
content: Why in the world would you post the same exact message in two forums on this board?

author: Zero999
author_rank: Super Contributor
timestamp: June 27, 2011, 05:17:08 pm
content: This happens quite often on other forums I visit, one of which I moderate. I just delete the thread, and PM them a polite reminder not to do it again.I've never understood why people do this, perhaps they think more people will look at their thread and give a helpful reply? The reverse is true most of the time and it's annoying when you've responded to one thread, only to discover someone posted exactly the same response to the duplicate thread.

author: ndictu
author_rank: Regular Contributor
timestamp: June 27, 2011, 05:28:24 pm
content: Quote from: Hero999 on June 27, 2011, 05:17:08 pmIt's one of those forum things like "google it" when there aren't any relevant results for your question, "never mind I solved it" without posting a solution and that thread is the only result for your problem and splitting one big question into several smaller threads, often on different boards.

author: sacherjj
author_rank: Frequent Contributor
timestamp: June 27, 2011, 05:46:45 pm
content: Original Poster, please provide TONS more detail before we can help. Wired or Wireless? What format video? Mono or Stereo audio?

author: johnboxall
author_rank: Unknown
timestamp: June 29, 2011, 06:12:44 am
content: Quote from: reeraslan on June 27, 2011, 09:31:55 amAs others have said - we need a lot more detail from you.Coincidentally I saw this advertised today, it may be of interest.http://www.jaycar.com.au/productView.asp?ID=AR1849

author: reeraslan
author_rank: Newbie
timestamp: June 29, 2011, 03:52:23 pm
content: thank you for all interests i found ithttp://www.gumstix.com/store/product_info.php?products_id=227

author: sacherjj
author_rank: Frequent Contributor
timestamp: June 29, 2011, 04:38:49 pm
content: Quote from: reeraslan on June 29, 2011, 03:52:23 pmCompletely different solution to the question you asked. Guess the audio and video is already encoded into TCP/IP.

author: Zero999
author_rank: Super Contributor
timestamp: June 30, 2011, 04:17:37 pm
content: Quote from: reeraslan on June 29, 2011, 03:52:23 pmDon't worry, next time you choose to spam the forum by creating multiple threads asking the same silly question I'll be ignoring it.
I am trying to build an active pickup, don't understand it's circuit tho. - Page 1
Forum section: electronics / projects

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: December 28, 2019, 08:21:13 am
content: so I am building an active humbucker pickup, I found an article on them but still don't understand it and the schematics are not there anymore since those websites were shut down I guess.AFAIK it uses some really clever techniques to change the tone and make it noiseless even without shielding and no ground to the strings.but I didn't understand it really.maybe someone here has a schematic for it or something or just gets it better.I found these forum treads on this:https://music-electronics-forum.com/showthread.php?t=9095http://www.freestompboxes.org/viewtopic.php?t=880&sid=a5aff6c9c99adfe8a9cc32b29ba5570a

author: rvalente
author_rank: Frequent Contributor
timestamp: December 28, 2019, 09:38:02 am
content: The first link takes you to a forum, the second is login protected.Please, post the circuit drawing directly.
Comparator input noise issue. - Page 1
Forum section: electronics / projects

author: kushal4269
author_rank: Newbie
timestamp: July 28, 2024, 09:09:23 am
content: I am using LM393 op-amp as zero crossing detection.circuit uses dual supply with positive and negative supply of 5V as I have differential signals.When I connect signal it creates square wave according to input, but due to inherent noise in input comparator output is also noisy near transition.Is there any way I can remove or reduce input noise when no signal is connected to opamp(i.e. inherent noise of input) So I can get clear output. I am using both the op-amps of dual op-amp IC LM393 as I have two different signals.

author: Circlotron
author_rank: Super Contributor
timestamp: July 28, 2024, 09:48:15 am
content: https://www.analog.com/en/resources/analog-dialogue/articles/curing-comparator-instability-with-hysteresis.html

author: moffy
author_rank: Super Contributor
timestamp: July 28, 2024, 12:05:32 pm
content: Further to what Circlotron has already mentioned, add some hysteresis or positive feedback to the comparator:https://www.ti.com/lit/ug/tidu020a/tidu020a.pdfhttps://circuitcellar.com/resources/comparator-hysteresis-2/
I bought cheapest $0.01 JFET so that you don't have to! - Page 1
Forum section: electronics / projects

author: dusan
author_rank: Regular Contributor
timestamp: April 08, 2025, 06:00:52 pm
content: Last month I was buying some parts and of course I browsed supplier's JFET section and saw this 1 cent JFET, the name is TF2123G-E5-AQ3-R and it's from UTC (Unisonic Technologies, Taiwan). They are for the capacitive (electret?) microphones, but JFET is a JFET right? I could not resist. So what's the catch for such a low price? The SOT-723 package is TINY. And I mean it, this is NOT the SOT-323, the smaller brother of SOT-23, this is even smaller package. I didn't have proper adapter board for it so I soldered it on SOT-23 adapter board (it doesn't fit but I soldered it anyway by using liberal amount of solder to bridge from the pad to the contacts, if this failed I would use MSOP-10 adapter board or something similar). Pinout is the same as MMBTJ201 (D, S and tip is G).It has slightly lower drain current than J201 otherwise is very similar. Interesting things happens in reverse mode (drain and source swapped), at 0.6V current suddenly starts rising, and indeed, datasheet shows reverse diode there and a resistor (multimeter shows 16MOhm in both directions, but hey, you save another cent for biasing resistor). I measured all the curves and then made a spice model, more info below.Once I had model I simulated simple common source amplifier and find maximal gain to be with 15k Rd, breadboarded it and it works, gain was 18x both in simulation and breadboard. All info including curves, charts and spice model is here:https://github.com/dvhx/jfet-model-maker/tree/master/data/TF2123G_E5_AQ3_R#readmeIn charts red is real, green is simulation.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: April 08, 2025, 07:53:21 pm
content: Quote from: dusan on April 08, 2025, 06:00:52 pmThe E5 grade specs 210-350uA at VDS =2V (which is quite a good banding for a JFET) - makes it a useful current source.What VDS did you test with, as your curve is slightly out of spec ?

author: dusan
author_rank: Regular Contributor
timestamp: April 08, 2025, 08:15:32 pm
content: 9V

author: Benta
author_rank: Super Contributor
timestamp: April 08, 2025, 08:17:54 pm
content: Quote from: PCB.Wiz on April 08, 2025, 07:53:21 pmVDS is uninteresting, but VGS=0 is, and will allow you to make 0.21...0.35 mA constant-current diodes. Cool for biasing purposes.