hybridfree/eevblog-posts huggingface dataset:
PSU Choice Help - Page 1
Forum section: electronics / beginners

author: dindondee
author_rank: Contributor
timestamp: March 23, 2015, 05:15:20 am
content: Hello,I would like to go ahead to purchase my first PSU. I've been using wall-warts and batteries and work mostly with micro-controllers and low power devices. I'm thinking a triple output between the Rigol DP-832 or the GW Instek GPD-3303S. What about the GPD-4303S, does anyone think that'll be better with the price difference?Or do you know something better, somewhere cheaper?Any help is appreciated. ThanksGPD-4303S -http://www.amazon.com/dp/B0094JU260/ref=biss_dp_t_asnGPD-3303s -http://www.amazon.com/dp/B005DTDZ8C/ref=biss_dp_t_asnRigol DP-832 -http://www.tequipment.net/RigolDP832.html

author: tautech
author_rank: Super Contributor
timestamp: March 23, 2015, 06:57:28 am
content: Have a look at the Siglent SPD3303 range:http://www.siglentamerica.com/pdxx.aspx?id=175&T=2&tid=17MemberFrankBussdid a review thread 18 months ago, there you can follow its development to the unit memberrf-loophas recently posted about.https://www.eevblog.com/forum/testgear/siglent-spd3303d-review/msg288251/#msg288251PS. Put your country flag in your profile for local market advice.

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: March 23, 2015, 09:21:00 am
content: I cannot recommend a specific model,but if you are mostly doing low power microcontroller stuff, I would recommend touse a PSU that does not have a fan. No need of large power, no need of noise.Two outputs is useful as you can pair them to get +/- power for some opamps. Precise voltage setting is better.I recently modified my PSU to get better voltage setting than in my original (low quality chinese ) 0-30V 3A PSU.https://www.eevblog.com/forum/projects/changing-pots-to-multiturn-in-a-30v3a-psu/
PSU Design Question (how does this work?) - Page 1
Forum section: electronics / beginners

author: g0mgx
author_rank: Regular Contributor
timestamp: November 12, 2017, 06:00:50 pm
content: HI All,I've been learning about linear PSUs and have come across an old schematic which uses Zener diodes to create a -4.7V 0V +33V rails, but I am very confused about the role of C1 which is an electrolytic, the +ve end of which seems to be connected to AC.Is anyone able to help me understand this please? Schematic excerpt attached.Many thanksMarkG0MGX

author: capt bullshot
author_rank: Super Contributor
timestamp: November 12, 2017, 06:19:41 pm
content: This circuit is an old trick to create an auxiliary voltage from a single secondary. It does AC couple the transformers output into the rectifier circuit D1/D2, providing an AC voltage shifted by a DC level. Rectifying this brings you the negative voltage. C1 gets charged when D1 is conducting because the transformers output waveform is at it's positive peak, and discharges then into C2 through D2 when the waveform is on it's negative peak.

author: Benta
author_rank: Super Contributor
timestamp: November 12, 2017, 07:56:18 pm
content: Yep, also known as a "charge pump". Simple and works well for low currents.

author: jimmc
author_rank: Frequent Contributor
timestamp: November 12, 2017, 08:14:48 pm
content: Note that the current drawn from the main (positive) supply must exceed that drawn from the negative supply for this to work.Jim
PSU for Commodore 64 - Page 1
Forum section: electronics / beginners

author: Lotus
author_rank: Contributor
timestamp: July 17, 2012, 11:45:58 pm
content: I would like to get my old C-64 running again.But the PSU is broken, and i need 5VDC, so I have been wondering!I got a LiPo charger, which can charge with 5VDC - BUT it will also supply a constant current ( i believe? )Wouldn't it break my old beauty if I forced it to accept 1-2 ADC ?

author: Ketturi
author_rank: Regular Contributor
timestamp: July 18, 2012, 12:03:59 am
content: C64 also needs 9VAC for sound chip and some other chips.QuoteLike wikipedia says.It will not work properly with only 5V DC.Also you might use that charger for 5V, but it charge voltage is probably over nominal 5 volts. PSU cant push more amperes in device than it takes at specific voltage. Constant current means that it gives no more than specified amperage by lowering voltage. I=U/R.I don't encourage to try with it nor built your own psu. My best opinion is to try find working original transformer, or buythisfor example(expensive thou). Or find cheap 5V switching wall pack and 9V transformer and connect them together to DIN connector.Do you still have orginal PSU? Somebody could be able to fix it.

author: amyk
author_rank: Super Contributor
timestamp: July 18, 2012, 10:30:50 am
content: I agree with fixing the old PSU.http://s3.postimage.org/lkxsv5fjl/untitled.pngLinear supply, extremely simple.

author: Nermash
author_rank: Frequent Contributor
timestamp: July 18, 2012, 10:57:31 am
content: If you are lucky to have the non-potted version...

author: Lotus
author_rank: Contributor
timestamp: July 18, 2012, 12:24:42 pm
content: The old PSU is embedded in some kind of gel stuff, completely inaccessible.I got the 9 VAC ready, I just need to find a 5 VDC source which can supply some where close to 1.5 A.

author: T4P
author_rank: Super Contributor
timestamp: July 18, 2012, 01:08:07 pm
content: 1.5A? No problem. They're everywhere and you can also probably use 2A
PSU - getting +12, -12 and 0 volts - Page 1
Forum section: electronics / beginners

author: level6
author_rank: Regular Contributor
timestamp: February 21, 2019, 08:33:12 pm
content: I just purchased a Siglent SPD3303X-E bench power supply. It has three outputs, one of them being a range of fixed voltages, the other two being fully adjustable.What I need is to be able to get +12, -12 and 0 volts from the unit. Would I do this by setting the outputs to independent mode, set both to 12 volts, then combining the inner + and - terminals to get my zero volt, using the remaining terminals for the + and - voltages?

author: MarkF
author_rank: Super Contributor
timestamp: February 21, 2019, 09:37:25 pm
content: Answered in another thread.https://www.eevblog.com/forum/testgear/positive-n-negative-voltage-with-siglent-spd3303x-e/

author: jeroen79
author_rank: Frequent Contributor
timestamp: February 21, 2019, 09:42:25 pm
content: Going by the datasheet it supports independent, series and parallel modes.Series mode is what you're looking for.

author: level6
author_rank: Regular Contributor
timestamp: February 21, 2019, 09:48:42 pm
content: Quote from: jeroen79 on February 21, 2019, 09:42:25 pmSo serial mode and combine the remaining terminals as the zero reference?

author: Moriambar
author_rank: Unknown
timestamp: February 21, 2019, 10:37:15 pm
content: Quote from: jeroen79 on February 21, 2019, 09:42:25 pmlet me add to this question: what would it happen if I were to short the + of one channel to the - of another channel (both active) in idependent mode?Cheers

author: level6
author_rank: Regular Contributor
timestamp: February 22, 2019, 01:28:13 am
content: I figured it out. Set to serial mode. The remaining terminals are zero volt. You can test by checking the voltage, should be 1/2 the output between the outer + or - terminals and any of the center ones.
PSU Lab - Page 1
Forum section: electronics / beginners

author: StormBugz
author_rank: Newbie
timestamp: September 07, 2021, 11:58:04 pm
content: Hello, I wanted to take a lab feed, I found several- Korad KD3005D- Korad KA3005P- Korad KD6002D- UNI-T UTP3315TFL- UNI-T UTP1310- UNI-T UTP1306SWhich would you recommend to me?Thanks

author: t1d
author_rank: Super Contributor
timestamp: September 10, 2021, 01:24:38 am
content: Hi, StormBugz, and welcome to the forum.I see that it has been a couple of days and you have not had any replies. I didn't want for you to feel ignored and I thought you might could benefit from some tips about this forum.The culture, here, seems to be that the "community" expects you to do your own research. You have asked a very broad question about very specific PSU models.1) It is not likely that any single person is going to know the features of all those models and have made a comparison to know which is "best."2) Which is "best" is very much a function of what your particular needs are. You have not stated your needs.At most you could have only hoped that someone would have directed you to some general introduction to PSU functions. The worst that you could have expected is what you got - silence.So, let's work together toward getting the information that you need and want... Here is what I suggest:- Google for PSU types and functions. YouTube has great electronics videos.- Make a list of the functions you need and what you would like. That is two different things.- Determine your budget. Even if you do not have much money, do not become discouraged. For a PSU, there are lots of ways to make your own.- Determine very specific questions about comparisons between particular models and post you those questions on this forum.I am not a forum moderator, or anything like that. I just want people to feel included and to get the information that they want. We would love to help you sort through the information that you find.

author: perieanuo
author_rank: Frequent Contributor
timestamp: September 10, 2021, 09:13:01 am
content: you put up here apples and pears, 30V and 60V ps'syou didn't specify what you need in voltage/amp, so we cannot adviselab is vague, there are all sort of labs, if you gonna so smartphone repair, nu need for 60V but for 5A or moreall that hw you pointed is for hobby, the lab ones are some other storyfor a real lab, you need more than one ps, at least one analogic one, more current capability (yes, in any lab at one time you need more than 5A), etcaetera
PSU & PCB Placement - Page 1
Forum section: electronics / beginners

author: jnestor481
author_rank: Newbie
timestamp: January 20, 2025, 07:03:28 pm
content: Hello All,So I'm doing a personal project PCB and am considering placing a small Traco power supply (PN: TMR 3-2423WI) on the board. The max current draw I expect to see is around 50mA on either rail. But I also have sensitive millivolt level signals coming from a sensor and going into an instrumentation amplifier on the board. I'm not certain if this is a wise idea or not.I was planning on having the board be about 2.25" (57.15cm) square, and have 4 layers with 2 power planes for positive and negative 15V, and the top and bottom would be signal layers with a ground pour stitched together with vias. But yea just not sure if placing a power supply about 3/4" (1.9 cm) away from sensitive millivolt level signals would be a dumb idea or not. Any advice would be much appreciated. Thanks.

author: thm_w
author_rank: Super Contributor
timestamp: January 20, 2025, 10:45:26 pm
content: Switching frequency says 100kHz minimum. So you may get some noise in that area. Though its a 3W converter, and 50mA is very little draw so if you shield the traces I can't see it being much.You can also consider what rail is powering the converter, and having a spot for filtering ahead of the converter. Which can be shorted out if not needed.Is your sensitive signal DC or relatively low frequency? If so most of the noise can be filtered out.

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: January 22, 2025, 12:43:16 pm
content: Place the power supply as far away as possible from the sensitive analog section. A distance of 3/4" may work. Isolate the power planes for the ±15V supply from the ground plane.These planes should not directly overlap sensitive analog traces on adjacent layers.
PSU precision requirements - Page 1
Forum section: electronics / beginners

author: kt315
author_rank: Regular Contributor
timestamp: April 20, 2013, 08:08:21 pm
content: There are currently a few threads in the projects section discussing PSU precision or voltage references (with intend to be eventually used within a PSU).What are the applications that would require sub millivolt precision/resolution from a lab PSU?

author: mikes
author_rank: Regular Contributor
timestamp: April 20, 2013, 08:28:03 pm
content: Quote from: kt315 on April 20, 2013, 08:08:21 pmWorking with thermocouple circuits is an obvious one.

author: c4757p
author_rank: Super Contributor
timestamp: April 20, 2013, 08:52:47 pm
content: Not a general list of applications, but just on my personal workbench:I have an ancient Power Designs model with rated 0.1% precision (usually tests around 0.05%) and 1mV resolution + vernier. I use it all the time as a variable reference just for the sake of convenience (e.g. if you're trying to measure the ratio of Vout/Vin, it's nice to be able to just set Vin to exactly 1.000V and have the ratio show up right on the voltmeter display), and I've used it in a pinch to calibrate shitty (analog) meters. I also have made up some bodgey "precision" gear (DC load, etc) that, instead of having a digital input, takes an analog input reference voltage, "borrowing" the precision decade dials for a cheap and convenient way to dial in an exact setting.

author: kt315
author_rank: Regular Contributor
timestamp: April 21, 2013, 02:32:09 am
content: It makes sense, I guess I can see how it can be used as a reference. Thanks.
PSU: recommended layout for the front panel - Page 1
Forum section: electronics / beginners

author: exe
author_rank: Unknown
timestamp: March 02, 2016, 08:36:55 pm
content: Hi!Which of those two layout would you prefer and why?(there supposed to be two pots, but at the moment I have only one). I'd go for the meter in the middle because this way I won't accidentally touch the output connectors while adjusting the knobs, and I will not touch the knobs while connecting something. The downside: the hand may cover the display while adjusting. The output is up to 15V if it matters.It's horizontal bench PSU.PS: Whoops, forgot to tell, there supposed to be two independent outputs. On photo there is only the first one...

author: Chalcogenide
author_rank: Regular Contributor
timestamp: March 02, 2016, 08:44:10 pm
content: Will you keep the meter on the bench or higher on a shelf?With the meter on the top of the panel your hands won't block the visibility while adjusting the pots if you keep it on the bench.

author: exe
author_rank: Unknown
timestamp: March 02, 2016, 09:21:02 pm
content: Quote from: Chalcogenide on March 02, 2016, 08:44:10 pmGood question! I'm going to keep it on the bench. I wanted to put my soldering station on it... Unfortunately, not the best arrangement because iron's wire get in the way... But just tried to mockup how I would use it and I think the "classical" knobs/meter arrangement is better anyway...*me scratching my head.

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: March 02, 2016, 09:21:28 pm
content: I don't think I'd put anything that close to the lugs. Can you put stuff on the right side of the case?

author: exe
author_rank: Unknown
timestamp: March 02, 2016, 09:54:39 pm
content: Quote from: Galaxyrise on March 02, 2016, 09:21:28 pmHuh, sorry, I forgot to say that there supposed to be two independent channels. Hence, I need to leave half of the space empty for another channel.I do realize that with such constraints there is no ideal solution. The reason I'm trying to put so many thing in one small box is the very limited bench space. Basically, all I have is a table 76cm x 59 cm (width and depth).

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: March 02, 2016, 11:41:15 pm
content: Hmm. Of the two options you presented, I think the "standard" arrangement would be the display on top.I don't see any consideration for power or channel on/off switches.Perhaps you could go for something less symmetrical, like this:

author: exe
author_rank: Unknown
timestamp: March 03, 2016, 09:29:43 am
content: Quote from: Galaxyrise on March 02, 2016, 11:41:15 pmI forgot it, thanks for reminding. But it is quite small (the PSU is only 30W), so I hope I still can fit it somewhere.Quote from: Galaxyrise on March 02, 2016, 11:41:15 pmThank you for your efforts. I considered this too, but I think there is a danger to confuse read outs. So I can look at the display and turn the wrong knob. This did happen to me, so I would like to go with a symmetrical design.
PSU repair questions - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: May 18, 2015, 10:41:54 am
content: I got an odd ball custom built PSU at a rally yesterday, for virtually nothing. Apparently custom built for some testing purpose in a production environment it basically consists of a computer SMPS unit in a nice case, with a bespoke PCB. feeding panel sockets. It appears in use it had USB control of some functions, and also has a serial port. The grey wire out the front of the panel terminates in a USB plug. The computer SMPS outputs are fed to the custom PCB and there are banana sockets on the front panel for +15V, -15V, +12V, -12V, +5V and -5V.I am seeing the following under test from these sockets, in the same order as above: 11.6V, -0.1mV, 12.16V, -11.3V, 5.05V and -5.04VI am guessing the 15v is derived from a DC to DC converter circuit from 12V perhaps, and that's what the coil and choke are for? You can see photos athttp://www.chriswilson.tv/psu/psu.htmlI will try and attach a few below, too. There are also some small IC's with two loops of insulated wire around them, and I have never seen anything like that before, any ideas why they have done this?I was going to use the supply (forgetting about USB /serial control) just to run breadboard experiments using OpAmps that need + and - 15 rail supplies. Without a circuit diagram I need assistance with ID'ing what part of the circuit may be at fault. The SMPS itself outputs sensible voltages to the PCB, although (assuming it's even used) the -12V is low at around -11.3V. I suspect they may have got the split 15V supply with a resistor divider network, hence perhaps the 4 big 1k resistors? Guessing though.... Thanks for any tips. I can upload more specific photos if desired.

author: alanb
author_rank: Frequent Contributor
timestamp: May 18, 2015, 11:32:38 am
content: ICs with wire round them - possibly Hall effect current monitoring.

author: tron9000
author_rank: Frequent Contributor
timestamp: May 18, 2015, 12:20:30 pm
content: From the very small ID number on the photo's, I Did a google search - could they be these?http://www.melexis.com/Current-Sensors/IMC-Hall-Current-Sensor-ICs/MLX91205-689.aspx

author: Chris Wilson
author_rank: Super Contributor
timestamp: May 18, 2015, 12:48:07 pm
content: Quote from: tron9000 on May 18, 2015, 12:20:30 pmOh! Wow! Well spotted, I have got a lens on them and they do indeed look like 91205 units! I guess the box of tricks was for testing some other device and moonitoring current consumed, maybe at different voltage levels, and logged via USB?After determining input voltages to the board wewre present I pulled the wired end electrolytics and tested them, all 4 were fine.I attach another photo, I have marked interesting IC's with part numbers.If we assume U12 is for current monitoring and it should have -15V on its current sense wire, it doesn't, I need to work out how the 15V levels are derived now.Thanks for the replies.
PSU voltage spikes when turning mains on or off - Page 1
Forum section: electronics / beginners

author: Mike Fikes
author_rank: Contributor
timestamp: January 12, 2018, 07:25:52 pm
content: I have a Korad KA3005D, which has an "Off/On" button for controlling whether the output is delivering power. This works fine in terms of regulating the voltage during these transitions.But, I've noticed that when pressing the mains power button, the voltages can involve significant spikes. (Attached is a capture of the voltages when turning off the unit, where the oscilloscope probes are connected directly to the PSU output leads.)Is this normal in PSUs? I'm still learning, but am presuming that, given this, it is prudent to not have the PSU connected to the DUT when turning mains on or off.

author: Mike Fikes
author_rank: Contributor
timestamp: January 12, 2018, 07:47:46 pm
content: I think I was too quick to post / blame the Korad for the spikes, as I see them (or similar ones) on the oscilloscope trace when the scope probe is connected to the DUT rails (otherwise floating, unpowered), and the Korad's power is simply turned on or off. Perhaps this is jut the Korad's transformer causing ground reference to waver?I have the Korad and Rigol both plugged into a Tripp-Lite Isobar power outlet strip (in separate "isolated filter banks", but perhaps this is insufficient to prevent the observed phenomenon).

author: mcinque
author_rank: Unknown
timestamp: January 12, 2018, 09:10:27 pm
content: Did you check it with a proper bnc cable connected to a banana adapter like this to avoid picking up any interference with the ground clip of the dso probe? The ground cable of the probe can act like an antenna and pick up noise in the surroundings.My rebranded KA3005D has some spikes at startup (not bad like that you posted, maybe you're picking some EMI coming from the power switch) but the worst feature is that it has 700mV overshoot for some mS when you enable the output. It's considered somewhat "normal" for a cheap programmable psu.

author: Mike Fikes
author_rank: Contributor
timestamp: January 12, 2018, 09:38:43 pm
content: No. Thanks. I'll look into getting proper BNC connectors.When enabling the power for 5 V, I can confirm that I see a 440 mV overshoot on the KA3005D.

author: mcinque
author_rank: Unknown
timestamp: January 12, 2018, 09:43:36 pm
content: Mine is worse than yours
PSU wiring dilemma... - Page 1
Forum section: electronics / beginners

author: LektroiD
author_rank: Frequent Contributor
timestamp: June 25, 2018, 02:56:17 pm
content: Hi, I just did a continuity check on my switching PSU but the ‘COM’ which I presumed to be common ground are not connected to each other and also isolated from the chassis of the PSU, I’m wondering if I should tie all the COM connections and the chassis to mains ground (is it safe to do so)?

author: bob225
author_rank: Frequent Contributor
timestamp: June 25, 2018, 03:05:22 pm
content: standard switch mode ? all the outputs are isolated and not reference on the dc-dc transformer - don't tie it to ground, and you don't really want it referenced to earth or the mains, that sort of defeats the filtering

author: LektroiD
author_rank: Frequent Contributor
timestamp: June 25, 2018, 03:20:30 pm
content: Yes, switch mode...So I'm guessing this is unusable for my purposes, as my power bus needs a common ground for all voltages... The +5V will not work from the COM of the +/-12V

author: stj
author_rank: Super Contributor
timestamp: June 25, 2018, 03:46:38 pm
content: you can tie the outputs if you need to i imagine.nice selection of voltages, where did you get it and what's the output ratings?

author: LektroiD
author_rank: Frequent Contributor
timestamp: June 25, 2018, 04:32:06 pm
content: Quote from: stj on June 25, 2018, 03:46:38 pmIt didn't explode, so all good.Quote from: stj on June 25, 2018, 03:46:38 pmOne of AliExpress' finest, although I cannot find that particular one now...Specs:+5V 5A+24V 1A+/-12V 1A

author: bob225
author_rank: Frequent Contributor
timestamp: June 25, 2018, 05:54:37 pm
content: it looks like one of the meanwell clones

author: stj
author_rank: Super Contributor
timestamp: June 26, 2018, 10:41:36 am
content: not good enough for me,i was hoping for 24v at 3A+ and 5v at 8A+
PSU with LM317 - Page 1
Forum section: electronics / beginners

author: Lyren
author_rank: Newbie
timestamp: September 21, 2014, 10:08:09 am
content: I have looked at thishttps://www.eevblog.com/forum/projects/bench-power-supply-0v-~-15v-cccv/msg264407/#msg264407But I am a bit confused about the current resistor, is it really only 0.01 ohm? After what I can see its not more than ~ 15 cm AWG24.Would it be possible to add a bypass NPN to increase the current to 3-5 A?

author: TriodeTiger
author_rank: Regular Contributor
timestamp: September 21, 2014, 10:22:24 am
content: Your homework: What configuration is the current sense amplifier opamp, and what is the gain?How many volts per amp of current (V = IR) will come out of the resistor, and the opamp, respectively?What voltage is being fed in to the current limit opamp to be compared to the current sense amplifier output, and what does it in fact try to regulate the current to since you know the voltage ratios? (random example: non-inverting = 1V, inverting input = 0.1V, and if at 1V per A, therefor it strives for a 100mA limit.)Why may a low value resistor be useful when high currents are used? Burden voltage, is a key term.QuoteAs long as the return path includes the sense resistor, I do not see why not!Tiger.

author: Lyren
author_rank: Newbie
timestamp: September 21, 2014, 11:42:08 am
content: The gain in current sense amp must be ~100 and at one Ampere we have .01x1x100 ~1V but the voltage divider 1K and 10k will give from 0 to 4.5 V so I fail to see how it works.I think the output voltage of LM317 is regulated by the voltage on adj. If the current and there by the voltage out of current sense amp gets to high it would lower the output voltage. But I fail to see how.

author: mikerj
author_rank: Super Contributor
timestamp: September 21, 2014, 09:48:08 pm
content: Quote from: Lyren on September 21, 2014, 11:42:08 amIt may work within a small range of the current setting potentiometer, but I agree that the divider is incorrect. R7 should be 23k to get 0-1.5 Amps range.

author: David Hess
author_rank: Super Contributor
timestamp: September 24, 2014, 10:35:07 am
content: Quote from: Lyren on September 21, 2014, 10:08:09 amA PNP bypass is simpler but it could be done by driving an NPN with a PNP.The current shunt is an usually low value because it directly degrades the load regulation in this design.

author: Lyren
author_rank: Newbie
timestamp: September 25, 2014, 12:13:18 pm
content: After I build the circuit and it is my impression that it is Current limit, not cc, is that correct.What I was after was a easy lab supply with cv/cc.
PSU Works on breadboard not on PCB? - Page 1
Forum section: electronics / beginners

author: lesabb
author_rank: Contributor
timestamp: March 22, 2015, 03:19:44 pm
content: Hello all, I have used the following shematics to build a 24V and 48V PSU. For various reasons I thought I would split the schematics in 2 pieces (2 PCBs) as shown in Schematics #2. Then I would simply connect the 24V PCB to the 48V PCB as shown in the 3rd picture. I also connected the ground planes. When I connect the 2, I get 24V on the 24V out BUT always get 67V on the 48V output as if there is no regulation. I can't find find any shorts and I printed the 48V PCB twice. Am I missing something on the ground planes?Thanks

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 22, 2015, 03:25:53 pm
content: Show your breadboard.

author: lesabb
author_rank: Contributor
timestamp: March 22, 2015, 03:30:00 pm
content: Sorry T3, I took it apart to assemble the PCB!!AND in fact I used the 24V board to send to the 48V on breadboard. I'm stumped.

author: albert22
author_rank: Regular Contributor
timestamp: March 22, 2015, 05:04:25 pm
content: check the diode in parallel with the 48v regulator you may installed it the wrong way.If ok then the regulator may be bad or a short in the pcb. Check with an ohmmeter.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: March 22, 2015, 06:31:16 pm
content: Hi,Remove C5. Connect the bottom of C4 to the top C6.I think it should work then.Regards,Jay_Diddy_B

author: lesabb
author_rank: Contributor
timestamp: March 23, 2015, 05:20:05 pm
content: Thank you all for pointing me to potential problems. Found it! The diode across the 783 was fried! So I'm assuming that everything was going around the 783?
PSU YP1504PG - Page 1
Forum section: electronics / beginners

author: Daxxin
author_rank: Regular Contributor
timestamp: April 13, 2017, 03:41:14 am
content: Power supply LG M1921A vga+tv tuner monitor faulty , very similar schematic instead 12v i have 15v but actually measuring +49v and +17v instead +5vshorted transformer? alredy check diodes mosfet and bridge all ok , optoisolator faulty can let the DC go till the output?

author: CJay
author_rank: Super Contributor
timestamp: April 13, 2017, 07:04:57 am
content: Check the capacitors on the output, if you're measuring the voltage with no load and they're faulty you will see some really odd voltages.
PSU's in series, common cathode Schottky diodes questiom - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: August 15, 2021, 11:45:08 am
content: 3 series connected SMPS units. I want to protect them with Schottky diodes on their outputs. I have three 30CPQ100PbF devices. TO247 cases. Common cathode 100V , 2 x 15A. Can I fit them to each supply so the junctions are in parallel, with the 2 anode wires in parallel to double the Amperage rating?Thanks.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: August 15, 2021, 12:21:24 pm
content: What is it that you are actually doing?When you put power supplies in series, they each have the same current.Paralleling diodes is not a good idea. Diode's have a negative temperature cooficient, so the hottest diode will carry the most current and get even hotter. You can put resistors in series to partially equalize these currents, but that causes extra power and voltage loss.What sort of power supplies are you using that 15A diodes are not enough?Find some diodes that can handle the current, or if that is not possible, then thermally coupling the diodes also helps.And why put a diode in series with each power supply? Each power supply has the same current when they are in series, so one diode (if used at all) is enough (but it must be able to block the combined voltage of those power supplies.

author: Chris Wilson
author_rank: Super Contributor
timestamp: August 15, 2021, 01:41:25 pm
content: I need 32 volts at about 32 Amps for a 2.4 GHz digital TV amplifier. Someone here in the UK has modified three HP server supplies to give about 10.57 Volts each instead of 12.4 volts by changing a resistor on one leg of the voltage trimmer pot inside and isolating the outputs from chassis ground. He puts them in series with a Schottky across each one. Each supply is good for about 80 Amps so they are not being run hard. Does that tell enough of what I am trying to do with the protection diodes? Thanks very much for the reply.http://www.chriswilson.tv/psu.docx

author: David Hess
author_rank: Super Contributor
timestamp: August 16, 2021, 01:59:55 am
content: Quote from: Chris Wilson on August 15, 2021, 11:45:08 amAs far as I know, double diodes can be used in parallel. Current sharing is considerably helped by having the semiconductor dies share the same substrate.

author: viperidae
author_rank: Frequent Contributor
timestamp: August 16, 2021, 02:24:10 am
content: If the diodes are across the terminals of each PSU in series, the only time they will pass current is when the corresponding PSU is turned off.It would prevent power being reverse fed back into the powered down PSU by the other two.Presumably only for fault conditions like over current cut out and power up sequencing.

author: Kleinstein
author_rank: Super Contributor
timestamp: August 16, 2021, 05:39:47 am
content: The double diode can be used in parallel. The current rating would no really double, but still get better than a single diode, as the heat removal is still limiting.With SMPS for computers one has to check if the output is connected to PE.
PT100 3 wire probe to Keithley 6100 - Page 1
Forum section: electronics / beginners

author: cowasaki
author_rank: Frequent Contributor
timestamp: May 31, 2018, 09:48:06 pm
content: I’ve bought a PT100 probe with three wires. Does anyone have details of how to connect this to a four wire multimeter. I have a Keithley 6100

author: C
author_rank: Super Contributor
timestamp: June 01, 2018, 02:46:32 pm
content: If you want a good remote sense you need to take the current used into account.A PT100 is a temperature controlled resistor.As temperature changes current changes and as all wires have resistance the voltage drop on the wires changes.So you have the current to run the PT100 changing.Your voltmeter is built to use very low current, so a voltage change is a small current change.A four wire PT100 would let your voltmeter measure the voltage at the PT100. Less wires then this will give you errors.A three wire PT100 interface is enough connections to correct for wire drop if you assume that the two wires that have PT100 current have the same resistance.From three wires you can measure three values.One of these is wire voltage drop.You then use the three values to computer the actual PT100 value.C
PT1000 Sensor Error - Page 1
Forum section: electronics / beginners

author: alnstn10
author_rank: Contributor
timestamp: July 04, 2022, 02:15:52 am
content: Why does the pt1000 sensor error when testing using the EVAL-CN0359-EB1Z analog device, even though when tested using a multimeter, the sensor still has a resistance of 1023 ohms and will increase as the temperature gets higher?Is there a way to fix it so that pt1000 can work again?

author: ledtester
author_rank: Super Contributor
timestamp: July 04, 2022, 03:01:23 am
content: If you don't get an answer here you might try asking in Analog's EngineerZone forums:https://ez.analog.com/subgrouplistThere have been a lot of questions asked there about the CN0359:https://ez.analog.com/search?q=CN0359
pt1000 sensor suddenly error  - Page 1
Forum section: electronics / beginners

author: alnstn10
author_rank: Contributor
timestamp: June 28, 2022, 08:26:42 am
content: If the pt1000 sensor suddenly error while testing the water temperature rise using the analog devices EVAL-CN0359-EB1Z, is the sensor damaged? how to find out the damage?

author: tszaboo
author_rank: Super Contributor
timestamp: June 28, 2022, 08:43:05 am
content: Water got into it. Maybe it dries out and then it works fine, but depending on the probe construction, it might have dissolved flux, and brought it where it's not supposed to. And made irreversible damage.
PTC for pasting on CHG/DSG mosfet for overtemperature protection - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: October 21, 2016, 07:16:31 am
content: 1. I have made a ckt on Bq40z50-R1. PTC is used for protection of thermal runaway of CHG/DSG mosfets.2. Datasheet recommends PRF18BA103QB1RB, whose datasheet can be found here:https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwiC1Pqwq-vPAhVHsI8KHRebAVIQFggkMAE&url=http%3A%2F%2Fwww.murata.com%2F~%2Fmedia%2Fwebrenewal%2Fsupport%2Flibrary%2Fcatalog%2Fproducts%2Fthermistor%2Fr01e.ashx&usg=AFQjCNGGoG30HwBUiS-u-NS4L9Z4vSz1bw&sig2=2t9uo3OeN1e1-fRCDuvxAg3. But I was looking for some thorugh hole PTC. Problem, is I am making this circuit for 15A current, So major current flows through CHG/DSg fets & tracks around are bigger, so I wont be able to closely place SMD PTC in close vicinity of fets. So I think in this case SMD ptc wont be able to serve anything here.4. I was looking something in this shape so that I can mount them on top of fets. This is NTC.https://www.google.co.in/search?q=10k+ntc&espv=2&biw=1366&bih=634&source=lnms&tbm=isch&sa=X&ved=0ahUKEwizyZ2JrOvPAhWMNY8KHZSVCNoQ_AUIBigB#imgrc=lt7bZbOTWrKlmM%3A5. I serached on digikey, but didnt find any suitable part.http://www.digikey.com/product-search/en/sensors-transducers/temperature-sensors-ptc-thermistors/1967095?k=ptc&k=&pkeyword=ptc&pv1989=0&pv866=7&FV=fff4001e%2Cfff803f7&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=256. Any recommended part?
PTC Resettable Fuse Identification - Page 1
Forum section: electronics / beginners

author: ziplock9000
author_rank: Regular Contributor
timestamp: December 29, 2016, 12:39:39 pm
content: I've got a lot of old components. Is there any way to identify PTC parts as none of the numbers of symbols are just codes and Googling doesn't help?

author: SeanB
author_rank: Super Contributor
timestamp: December 29, 2016, 01:56:40 pm
content: Well, the NTC thermistors and inrush limiters tend to be matt black, and the PTC fuses tend to be shiny yellow. Blue shiny tend to be ceramic capacitors though.

author: ziplock9000
author_rank: Regular Contributor
timestamp: December 30, 2016, 08:02:00 am
content: Quote from: SeanB on December 29, 2016, 01:56:40 pmThanks.
PTH test pins? - Page 1
Forum section: electronics / beginners

author: electrolust
author_rank: Unknown
timestamp: September 28, 2016, 12:59:08 am
content: I'm looking for test pins to put into a PTH. .030" dia .1" pitch. I found kinky pins andhttp://www.newark.com/oxley/028-30p-la-kp2-silver/terminal-kinky-pin-pcb/dp/11N6258?CMP=AFC-OPbut I can only find suppliers in the UK. Is there another vendor of this style test pin, with US availability? Keystone doesn't make anything this small AFAICT.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 28, 2016, 01:10:20 am
content: So a 5001 (et al) is off the table?http://www.newark.com/keystone/5001/test-point-pcb-through-hole/dp/62W5135Says 0.1" o.d., so they should stack (a little bit tightly) at that pitch. The hole will be a tight fit, but it looks doable..?Afraid I don't browse test points in detail, so I don't have anything to add that you probably haven't already seen or thought about before, anyway...Tim

author: tautech
author_rank: Super Contributor
timestamp: September 28, 2016, 01:12:28 am
content: These OK?http://www.digikey.co.nz/product-search/en/test-and-measurement/test-points/2294346?k=&pkeyword=&pv69=235&FV=fff40023%2Cfff8024a&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25Why not SMD, there's a much bigger selection.

author: Pack34
author_rank: Frequent Contributor
timestamp: September 28, 2016, 09:19:04 pm
content: I've always liked these:http://www.digikey.co.nz/product-search/en?keywords=5001K-ND
Public domain / Ancient programmable micro controllers? - Page 1
Forum section: electronics / beginners

author: maliqua
author_rank: Contributor
timestamp: February 06, 2015, 08:02:24 pm
content: Are there any ancient and simple by modern standards micro controllers that the schematics are publicly available for?I saw something that inspired me for another little side project, someone made a bench to look like a giant 555 timer, ti made me sad because it would have been easy to put a blown up sized 555 circuit inside of it, which made me want to do something similar, i want to try and un-miniaturize some ICs and make giant decorative ones. mostly because it sounds fun and not practical.here's a link the project that inspired my ideahttp://imgur.com/a/kTYBJ

author: DIPLover
author_rank: Regular Contributor
timestamp: February 06, 2015, 08:28:08 pm
content: Not a micro controller, but the Intel 4004 is arguably the first microprocessor and Intel have released the schematics for it.I don't think you will ever find simpler, but it is still a rather complex device (tremendously compared to a 555)http://en.wikipedia.org/wiki/Intel_4004is a good starting point.Please see attached schematic from Lajos Kintli (original Intel one was hand-drawn of course...).Schematic fromhttp://www.4004.com/Mask image also fromwww.4004.com, courtesy of intel.

author: amyk
author_rank: Super Contributor
timestamp: February 06, 2015, 08:54:32 pm
content: Here is an 8052:https://sites.google.com/a/satre-electronics.com/www/home/reverse-engineeringThere's also the famous 6502 which has been fully reverse-engineered:http://visual6502.org/

author: rdl
author_rank: Super Contributor
timestamp: February 06, 2015, 09:21:22 pm
content: There is a kit that's basically a giant 555 made from discrete parts. Dave did a review and build of it. If that's the kind of thing you want to do, you might want to check it out. Doing the same thing with even a simple micro controller would be a massive project.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: February 08, 2015, 03:49:34 am
content: Whoah, are you a set designer for old Dr Who?
Public Electronics lab in Toronto area (Mississauga/Brampton/Oakville) - Page 1
Forum section: electronics / beginners

author: Merlysys
author_rank: Regular Contributor
timestamp: June 14, 2015, 12:52:47 pm
content: I am setting up an electronics lab for hobbyists or even pros. It will be equipped with the usual scopes and meters etc. It will serve the communities as the distance from either of these 3 will be about 15 mins.It will be part of a larger Hackerspace/Makerspace. If you are able to help set it up please post details here or send me a private message (I think I can receive private messages, never tried to and I haven't posted here in a while). Space is already leased and we will begin moving the stuff on the 15th. No website yet so that is something to set up.

author: PeteH
author_rank: Unknown
timestamp: June 14, 2015, 08:18:23 pm
content: Even if I can in no way assist. It sounds like an interesting development for the area (I am not aware of any other labs like this in the area, I haven't actively searched though - maybe hacklab, far from west end though).My line of site from home to work is through two of these locations, feel free to keep us updated on the progress / any other set up tasks... maybe one will appeal to a passerby.

author: Tronto
author_rank: Contributor
timestamp: June 14, 2015, 08:26:29 pm
content: Quote from: Merlysys on June 14, 2015, 12:52:47 pmSounds great. Where are you setting up?

author: Merlysys
author_rank: Regular Contributor
timestamp: June 15, 2015, 04:53:16 am
content: Its at L7G 3P1Which is in a place that I don't like to mention the name of, Georgetown. I am afraid people will get discouraged because they never heard of it or think of it as some far off rural town. But upon visiting the site (driving from Mississauga) that I realized how accessible it is. From the 401's exit into Winston Churchill its just 15 mins away.I will have a pic of the building posted here soon.Any suggestions on where to advertise of its existence? I will post in the EDAboard and other forums, also on Kijiji and Craigslist community sections.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: June 27, 2015, 05:13:56 pm
content: Hi,Is there any news on this? I live in L7G xxx.Regards,Jay_Diddy_B
Published a board design, threw in an LTSpice tutorial - Page 1
Forum section: electronics / beginners

author: cellularmitosis
author_rank: Unknown
timestamp: March 22, 2015, 05:38:44 am
content: I recently designed a simple board to control headlight relays in my truck.In addition to publishing the KiCAD design on github, I decided to also document how I used LTSpice to simulate the circuit, and how that shaped the design process.I figured the beginners here might find it useful.https://github.com/pepaslabs/HeadlightRelayControlIn the future, I think I'll try to document my design process like this more frequently. Its very useful when you haven't touched LTSpice in 6 months and have forgotten everything you previously learned!
Pull down resistor on an RS422 receiver - Page 1
Forum section: electronics / beginners

author: Krumm
author_rank: Contributor
timestamp: April 22, 2016, 09:25:47 pm
content: Hello,If you could ahve a look at the attached circuit I have a 3 pin connector for an RS422 half-duplex signal and this is connected to a TI AM26LS33ACN (datasheet here:http://www.farnell.com/datasheets/1962946.pdf). However if there is nothing connected to the 3 pin connector, then according ot the receiver function table it outputs a high. What I'm wanting instead is for this to output a low.I'm going out on a limb here, but I think I need to put a pull down resistor between pin 1 and ground, and another between pin 2 and ground. I'm not sure if this is the correct way, or what resistor values to use?Thank you.

author: danadak
author_rank: Super Contributor
timestamp: April 23, 2016, 01:00:20 am
content: http://e2e.ti.com/cfs-file.ashx/__key/communityserver-discussions-components-files/142/2818.RS_2D00_422-Unused-Inputs.pdfMight be useful.Regards, Dana.
Pull down resistor question - Page 1
Forum section: electronics / beginners

author: Alfgan
author_rank: Contributor
timestamp: August 27, 2019, 05:27:03 pm
content: Hello everyone!Should I place pull down resistor near button? And if I should, what nominal it should be?

author: boffin
author_rank: Unknown
timestamp: August 27, 2019, 05:37:07 pm
content: Quote from: Alfgan on August 27, 2019, 05:27:03 pmYes, perhaps, and maybe. Depends on what you're using it for.In some cases you don't need a resistor at all as what you're feeding may already have a pullup (or pulldown) resistor.Case in point, the Atmel processors used in an Arduino, have a pullup you can enable with INPUT_PULLUP(aka pinMode(2,INPUT_PULLUP); to enable the pull up resistor. The only thing thing is you'll be hooking your switch from pin to ground instead, and your reading will show 0 when pressed and 1 when released, but that's easy in software.

author: Alfgan
author_rank: Contributor
timestamp: August 27, 2019, 05:47:15 pm
content: Thank you for informationSo in the situation above I do not need pull down or pull up resistor?This is a 555 dice and I want the dice to start when I press the button. I am not using arduino there.

author: Audioguru again
author_rank: Regular Contributor
timestamp: August 27, 2019, 06:01:40 pm
content: It is obvious that a pulldown resistor parallel with the pushbutton would keep the circuit acting like the pushbutton was continually pressed. Then the 555 would keep the LEDs spinning continuously.The transistor already has a pullup resistor (3.3M) that helps to turn it off as the 1uf capacitor discharges after the pushbutton is released.

author: Alfgan
author_rank: Contributor
timestamp: August 27, 2019, 06:22:09 pm
content: Oh thank you very much.

author: Damianos
author_rank: Frequent Contributor
timestamp: August 28, 2019, 09:10:03 am
content: The circuit operates with the resistance of a finger, that when touches the wires charges (partially) the capacitor and produces random results. If a button is used, then the capacitor will always be charged immediately to the battery voltage and the result will be more or less predicted.

author: Alfgan
author_rank: Contributor
timestamp: August 29, 2019, 09:29:56 am
content: Ooo oh okey thank you.So if I made a PCB with a button, should I just solder wire in the button footprint place?

author: Damianos
author_rank: Frequent Contributor
timestamp: August 30, 2019, 06:48:27 am
content: If you use the PCB alone, make two pads that can be easily touched by a finger. If you will use a box for the circuit, bring two wires with the "naked" ends attached to the outside, in a way that the sharp ends do not harm a finger.
Pull down resistor through LED? - Page 1
Forum section: electronics / beginners

author: MarkS
author_rank: Unknown
timestamp: August 01, 2023, 01:59:06 am
content: I have a series of signals that need to be pulled down, but need to have an indicator as to when they are at a logic high. I've never seen this done, although I assume it should be possible. The LED will obviously affect the pull down resistance and current. How should I account for that?

author: John B
author_rank: Frequent Contributor
timestamp: August 01, 2023, 02:07:30 am
content: Assuming a red LED, R26 could be increased maybe to 1.8k or so, then it would also be a good idea to add a resistor parallel to the LED, maybe 10k.

author: DavidAlfa
author_rank: Super Contributor
timestamp: August 01, 2023, 02:23:25 am
content: No, remember the led will drop 2V or so, so this won't be a proper pull.But you can place another resistor in parallel with the led+resistor, it will do the pull down properly and the led will work as intented.