hybridfree/eevblog-posts huggingface dataset:
Power sequencing multiple VCCO? - Page 1
Forum section: electronics / projects

author: Pack34
author_rank: Frequent Contributor
timestamp: February 24, 2018, 10:48:49 pm
content: According to the design notes for the Spartan6, the power rails can be brought-up in any order. However, I believe it's still a good idea to sequence properly.Now, the question is what should happen when you have multiple VCCO sources? Can the output voltage regulators be brought up at once? I believe this is the case.I'm using a TI LM3880 for power sequencing. I would assume that there wouldn't be an issue connecting FLAG3 to the ENABLE pin of four regulators since the signal isn't driving anything. Is this the case? I'm not seeing anything in regards to output current for the FLAG signals in the datasheet.For this design I have three different voltage levels for the FPGA and since it's a development board design, I'm powering the microcontroller with a separate power supply so that I can pull-off some shorting resistors and get an accurate idea of how much current everything is pulling.In the end this will be a battery powered application.LM3880 Datasheethttp://www.ti.com/lit/ds/symlink/lm3880.pdf

author: danadak
author_rank: Super Contributor
timestamp: February 26, 2018, 01:50:19 pm
content: PSOC one possibility, however this capability inside PSOC a small fractionalpart of the overall capability of PSOC, at increased cost.But you have control over basically all parameters of a power sequencing system.See attached screen shots of IDE setup. Note you are not limited to 4 sequence channels.The low cost board to use for dev would be -http://www.cypress.com/documentation/development-kitsboards/cy8ckit-059-psoc-5lp-prototyping-kit-onboard-programmer-andRegards, Dana.

author: Simon
author_rank: Unknown
timestamp: February 26, 2018, 09:43:14 pm
content: err the question was not about the PSOC ?

author: AndyC_772
author_rank: Super Contributor
timestamp: February 26, 2018, 09:47:13 pm
content: Quote from: Pack34 on February 24, 2018, 10:48:49 pmWhy?If the data sheet says they can be brought up in any order, then you don't need to sequence them.
Power source selection - Page 1
Forum section: electronics / projects

author: p07gbar
author_rank: Newbie
timestamp: May 28, 2012, 09:44:38 pm
content: I've been gently scouring the Internet for a while looking and thinking about a power selection circuit after someone asked, then I came up to a problem:Lots of boards give options for powering over USB or a barrel jack and therefore need a way to switch between: Arduino uses the op-amp as a comparator to switch a mosfet, but is it possible to use a mosfet just off the power rails or with single other transistors? The project I'm working on has quite tricky space and cost restraints so adding a op-amp seems kind of overkill.I've thought of using diodes to simply give priority however I feel there must be a neater way...Ideally I'd like to be able to draw about 300mA from the sources without anything getting too hot or magic-blue-smokey.I tried a fairly simple solution on a circuit simulator of using a "self-on" mosfet (Source and gate connected) on the dominant barrel rail and a p-channel with gate connected to barrel rail as well on the USB rail. I don't really know enough about MOSFETs to tell if this was working and the circuit sim. seemed to basically function with no components...Thanks in advanced for your help, I'm sorry to ask such a newbish question but the answer alludes me...

author: PA0PBZ
author_rank: Super Contributor
timestamp: May 28, 2012, 09:51:07 pm
content: Nothing wrong with diodes if you can afford the power drop, and otherwise you can always go old school: disconnect the USB power line when you insert the jack, like they do with battery/mains powered equipment

author: Psi
author_rank: Super Contributor
timestamp: May 29, 2012, 01:57:24 am
content: The common 1N5817 is about 0.32V drop at 300mA, that would make 4.68V available.I've also put multiple 1N5817's in parallel before to get the drop under 0.3v.There's also more specialized diodes like the LSM115J, which is 0.190V @ 300mA but a max of 15V(That one is surface mount)
Power Supply - Page 1
Forum section: electronics / projects

author: Ramzy
author_rank: Newbie
timestamp: December 08, 2017, 06:32:29 pm
content: Hi Guys,Thanks for stopping by. I just need some help with the two schematics I have. My idea was to build a power supply with protection on the outputs. I looked around online and found some videos and schematics that I'm using. The basic idea is to use a Buck-Boost setup to varry the voltage and the rest is done by the second schematic which will "protect the load". I just want to know:1. Is the idea feasible?2. In the schematics have I connected up everything up well enough to actually work?3. Any things I can eliminate.Any help is appreciated.Thanksps: Page 1 is the buck-boost section and Page 2 is the protection

author: David Hess
author_rank: Super Contributor
timestamp: December 09, 2017, 03:19:34 am
content: Quote from: Ramzy on December 08, 2017, 06:32:29 pmIt is feasible however I recommend against this method. The microcontroller is unnecessarily part of the feedback loop and this extra complexity results in lower reliability.A better way is to use external independent voltage and current control loops while having the microcontroller set the desired voltage and current limits while monitoring the results.

author: ocset
author_rank: Super Contributor
timestamp: December 09, 2017, 02:12:03 pm
content: yes agreed,and fig 3 pg12 of the LT3756 datasheet shows you a nice circuit to refer the high side voltage down to your ground referenceed protection.LT3756 datasheethttp://cds.linear.com/docs/en/datasheet/375612fb.pdf

author: Ramzy
author_rank: Newbie
timestamp: December 09, 2017, 04:51:21 pm
content: Thanks, so whay Im getting from the diagram treez pointed to is that I can make a constant voltage source from the setup.Fair and fine so I'm guessing I could simply remove the LED array. Would Rsen be therefore the current limiting factor? or have I lost it?With regards to what David said, how would you suggest I control the current through the microprocessor because I could see a way of controlling the voltage only through the mentioned Datasheet?
power supply - Page 1
Forum section: electronics / projects

author: electros6
author_rank: Regular Contributor
timestamp: February 23, 2014, 04:51:55 pm
content: hi guys,I am working on a power supply. I have attached the schematics herewith.basically the power transistor is fed from a constant current source . The conduction of the transistor is controlled by a opamp comparator using LM358. Everything works fine. I have two issues.1) when the power supply is loaded by 500ma the output voltage drops by around 200mv. The opamp is not correcting it.2) The output of the potential divider for sense , drops by more than 4 times even though the power supply output drops by only 200mv as said aboveeg) at 5 volt the potential divider out is 453mv but when it is loaded the putput voltage is around 4.83v by the potential divider output is drops to around 110mvplease help me

author: uwezi
author_rank: Unknown
timestamp: February 23, 2014, 07:53:58 pm
content: What's the positive supply voltage of your opamp?While the LM358 includes its own negative supply (GND in single supply configuration) in both its input and output ranges, this is not the case for the positive supply voltage.However, the voltage of your output potential divider should of coursealwaysbe 1/11 of the actual output voltage. This means for an output drop of 200 mV it should drop something like 18 mV. For 5 V at the output it must show 455 mV and for 4.8 V it must show 436 mV.If "it drops by more than 4 times" than something is wrong there! Or with the input of the opamp.
power supply - Page 1
Forum section: electronics / projects

author: Arlen moulton
author_rank: Regular Contributor
timestamp: November 18, 2014, 06:46:42 pm
content: I have a small Nokia 5volt transformer is there anything simple yet awesome I can do with it that doesn't envolve blowing it up?

author: Seekonk
author_rank: Super Contributor
timestamp: November 18, 2014, 08:38:39 pm
content: You could power that one transistor amp. It is what it is. If you bust it apart it probably has a zener in series with an opto isolator to control voltage. Replace that with a TL431 and it could be adjustable from about 4 to 12V. For those into solar, many of these electronic wall warts will work down to 50V (at reduced current) and provide an isolated source for a micro.

author: Paul Price
author_rank: Super Contributor
timestamp: November 18, 2014, 11:38:49 pm
content: It could be just a transformer, a simple non-switcher power supply as was first used with Nokia older cellphones.In this case, it would be just a small power transformer with rectifier diodes and a large valued filter capacitor, no regulation.If it is a wallwart type heavy, it's just using a transformer, otherwise it is a switchmode power supply.What it is good for is to supply a low-power around 3-5V /400mA circuit, and whether what it powers is something awesome or mundane is up to you to find.
Power supply - Page 1
Forum section: electronics / projects

author: Efichip
author_rank: Newbie
timestamp: August 05, 2024, 09:16:26 am
content: Hello.I make the flyback power supply with L6566B IC, but it's not starting. Can you help me to find the problem why it's not working, please?

author: Efichip
author_rank: Newbie
timestamp: August 05, 2024, 09:18:13 am
content: I make it by this project:
power supply - Page 1
Forum section: electronics / projects

author: kjn4685
author_rank: Regular Contributor
timestamp: April 12, 2015, 09:27:28 pm
content: Hi guys well I have another project. I have some power supplies that was found in a dumpster. They are kussmaul supplies so I am trying to fix them. The part number is 022-0082-1 they are 12v 20amp 115v in. I am wondering if anyone out there would have a schematic or block diagram. I would appreciate it very much. I also have a question what can I soak this pcb in to dissolve the coating on it.

author: kjn4685
author_rank: Regular Contributor
timestamp: April 13, 2015, 08:31:00 pm
content: I am sorry for putting this on the wrong topic. I could have put it on the repair topic.
Power Supply - Page 1
Forum section: electronics / projects

author: electronwaster
author_rank: Regular Contributor
timestamp: March 02, 2012, 11:16:48 pm
content: I'm designing and building a single linear power supply with controllable current and voltage, mostly to learn how these things work (i.e. how they regulate), and also as a way of furthering my basic understanding of electronics. I did post about this (at length!) in the beginners forum, but at least 60% of the discussion was about my chosen method of learning rather than discussing the power supply itself - perhaps that was my fault. I would rather discuss and improve the project itself, and I don't like to keep resuscitating an old thread, hence this new thread in projects.I've been watching Dave's PSU videos and learning lots, I think his overall design is focussed heavily on precision, low power, and microcontroller integration, not a perfect match for my needs, but I did pinch the idea about using a 1 ohm series resistor and some opamps to convert current to voltage, and then comparing that to a 0-1V pot for 0-1A and power the base of an NPN that controls output.The circuit that I ended up with at the end of the previous thread I made up onto stripboard and it's good, but not great. There is more voltage sag when I apply a load than the simulator simulated (surprise surprise), so I guess the internal resistance of the transformer is greater than I modelled, or some other departure from real life.Anyhow, that's done, and now I want to build one with a constant current mode too.My rough specs are as follows:0-15V output0-1A limitsingle input voltagesingle output voltageIf it works out, I'll just build another, and use them together as a dual supply with a nice toroidal transformer I have with two 25V secondary windings.I've attached a pic of the current circuit, it's not on the breadboard yet, before you ask. Can anyone suggest any improvements, or anywhere it might not work in real life?Thanks,electronwasterNotes:R15 is the load resistorR3+R4 is a facsmile of the current-control potentiometer, to turn the knob, I adjust the two valuesR5+R6 do the same for voltage.U1 spits out the voltage difference on either side of the 1 ohm sense resistor, R2U2 compares the 0-1V output of U1 with the 0-1V output of the current pot.Q1 can short the base of Q2 when in current limit mode, reducing the outputU3 is a buffer/voltage-follower, and needs to be rail-to-rail, to minimise load on the voltage pot, and drive the base of the pass transistor, Q2Please ask if anything is unclear.

author: TerminalJack505
author_rank: Super Contributor
timestamp: March 03, 2012, 01:02:15 am
content: Don't forget caps. Also, you'll need a resistor on the output of U3 to limit current when Q1 turns on.See attached. So far as the values go, they might need some tweaking.

author: electronwaster
author_rank: Regular Contributor
timestamp: March 03, 2012, 06:43:17 am
content: Hi Jack,Yes - I hadn't added a single cap yet, thanks for doing that for me. I'l add those to the circuit and reply to the thread with the updated version.Thanks,electronwaster
Power supply - Page 1
Forum section: electronics / projects

author: artur9n9
author_rank: Newbie
timestamp: July 24, 2012, 05:11:46 am
content: Questions:Every time when I put load around 2A the TR5 , TR4, and some times TR3 too blow up..Any idea??https://www.dropbox.com/s/khhrv33fxkycjfy/PS.pdf

author: David_AVD
author_rank: Super Contributor
timestamp: July 24, 2012, 05:49:09 am
content: What is the voltage on the input to the power supply?Also, what voltage did you have the output set to when drawing 2 Amps?

author: artur9n9
author_rank: Newbie
timestamp: July 24, 2012, 06:01:12 am
content: Input voltage is 45V and we are talking about 20v on the end.

author: David_AVD
author_rank: Super Contributor
timestamp: July 24, 2012, 07:09:34 am
content: OK, so that's a 25V drop (45V input - 20V output) across the series pass transistor.Multiply that by 2A (load current) and that's 50 Watts that the transistor needs to dissipate.That's within the transistor's SOA (Safe Operating Area) according to the data sheet, but is it on a substantial heatsink?

author: blackdog
author_rank: Frequent Contributor
timestamp: July 24, 2012, 08:50:35 am
content: Hi artur9n9The "designer" of this powersupply must be "Out Of His Vulcan Mind"...The biggest problem is the current limiter, this is so bad!!!It's at least 10.000 times to slow to protect TR5 and TR4.The parts around TR3 are also a mess, this wideband transistor wanna do only 1 thing "oscillate"Its a emittor follower with a low impedance base and a big capacitor on the emittor Bingo!!This powersupply "design" wil give you a lot of haedages.Kind regartsBram

author: artur9n9
author_rank: Newbie
timestamp: July 24, 2012, 06:21:05 pm
content: ***** The heatsink is realli big, with "hot pipe"( copper) and fan .***** Probably you are right. It is too slow.
Power Supply and Signal Generator Combo - Page 1
Forum section: electronics / projects

author: Russ1966nh
author_rank: Newbie
timestamp: March 11, 2014, 12:08:02 am
content: Hi All,My BK signal generator died this past Sunday...I will replace it later on this year, but in the meantime I had an idea I wanted to bounce off of the forum.I have been thinking about building a power supply with a built in signal generator. The power supplies that I have only go up to 12 volts and for most applications this is fine, but I would like to have on that goes up to 30VDC. Also, since I need a signal generator (just sine, square, and ramp) I thought I would just build everything into one unit...I figure it may be handy having everything in one box.I would run the signal generator off of a 12 volt tap coming off of the power supply. I am thinking of building a linear supply just to cut back on electrical noise, plus it's easier. I can foresee having to filter the power supply pretty well to keep transients out of the signals.Beyond this point (I am not at the design stage just yet) I don't see any real problems that would rule out doing this project, but I am wondering if anyone sees any problems that I haven't mentioned here.If anyone does see a problem or has suggestions I would love to have your input.Thanks in advance,Russ
Power Supply Box Project Questions - Page 1
Forum section: electronics / projects

author: OneADayTech
author_rank: Newbie
timestamp: July 24, 2014, 06:03:14 pm
content: Hello all!I'm building a wooden box to hold a 12V Power supply to power my lipo charger.I have a quick, extremely basic question. I'm still learning my basics and I'm just a little unsure about some things.Question 1:I ripped out an AC female power plug connector from an old power supply and it has this circuit board attached to it.Would it do any good to keep it on there or should I cut it off? It looks like it has a current transformer and a few other things on it.AC Connector:http://postimg.org/image/rmxkamz4nhttp://postimg.org/image/y7byw6babhttp://postimg.org/image/d0n911dm9http://postimg.org/image/qorcklm9pQuestion 2:I am also install an ammeter in the center of the box. Do all the the positive load lines need to be directly connected to the ammeter? Would my wiring diagram with two loads work?I'm having the pieces laser cut tomorrowThank you for any help!

author: void_error
author_rank: Frequent Contributor
timestamp: July 24, 2014, 10:17:24 pm
content: That's not a current transformer, it's a common mode choke, used for the PSU mains input filter. I assume the power supply you're using already has one built in so you can remove the one on the connector.The ammmeter should be in series with the loads.

author: tautech
author_rank: Super Contributor
timestamp: July 24, 2014, 10:44:10 pm
content: Your diagram looks correct.The wires from the current shunt to the meter do not need to be heavy cabling as the meter reads only the voltage across the current shunt.You will have to check the wiring polarity for the ammeter to display the correct current draw polarity.

author: OneADayTech
author_rank: Newbie
timestamp: July 28, 2014, 03:04:19 am
content: Thanks guys!Just thought I'd post the final results. Main goal was to win some cool points from my friendsTime to charge some batteries in style!

author: Ribster
author_rank: Frequent Contributor
timestamp: July 29, 2014, 04:36:33 pm
content: So much overkill, but so nice
Power supply circuit - looking for help. - Page 1
Forum section: electronics / projects

author: avitsur
author_rank: Contributor
timestamp: February 20, 2022, 12:08:41 pm
content: Hi,I've purchased this power supply kit from Aliexpress. it came without any documentation and I hope that you will be able to help.There are two potentiometers, marked "2" and "3" in the circuit diagram. if I'm not wrong, "3" is the output voltage setting and "2" is the current limit setting, indicated by the D12 led. what is the purpose of the trimpot marked "1" and how to set it?Thanx for your help and any additional info/remarks.psu.pdf(477.36 kB - downloaded 72 times.)

author: xavier60
author_rank: Super Contributor
timestamp: February 20, 2022, 01:18:30 pm
content: Quote from: avitsur on February 20, 2022, 12:08:41 pmYes, that's right about "2" and "3" and the LED, The trimpot is the offset null adjustment for the CV opamp.It's purpose is to adjust the PSU's output to zero volts when the voltage pot is set to minimum. It would be close enough anyway.
Power Supply Company Recommendations - Page 1
Forum section: electronics / projects

author: elimenohpee
author_rank: Contributor
timestamp: February 19, 2020, 06:48:04 pm
content: I have a project at work that requires some DC power supplies for use in some industrial applications. I've used Vicor in the past with good results, but I'm not aware of a similar company that has turn-key products that don't require a lot of development time. I wanted to compare products/capabilities before picking the first thing I saw.Does anyone have a recommendation for a similar company as Vicor that has a large catalog of DC power supplies that could be used in an industrial environment?

author: tooki
author_rank: Super Contributor
timestamp: February 19, 2020, 07:25:58 pm
content: There are these cool distributors that carry lots of brands, which is a great way to get an overview. Places like Digi-Key, Mouser, Newark, Avnet, Arrow...(In other words, do a bit of homework on your own first!)

author: elimenohpee
author_rank: Contributor
timestamp: February 19, 2020, 08:31:26 pm
content: I did a lot of filtering on digikey and mouser, I was just seeing if anyone had specific experience with a specific company.

author: Vgkid
author_rank: Super Contributor
timestamp: February 20, 2020, 12:25:05 am
content: Size ,power rating, voltage input, number of outputs...Traco, tdk/ lambda

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 20, 2020, 01:08:03 am
content: Mean Well is one brand that comes to mind.

author: ANTALIFE
author_rank: Frequent Contributor
timestamp: February 20, 2020, 02:11:59 am
content: I just made a list of medical grade power supply manufacturers:https://www.eevblog.com/forum/projects/list-of-medical-grade-power-supply-manufacturers/
Power supply connector  ??? - Page 1
Forum section: electronics / projects

author: TarHeelTom
author_rank: Newbie
timestamp: October 26, 2014, 07:21:53 pm
content: Found a good deal on several small multi-voltage power supplies.There is a connector to plug the incoming ac line into the board, but I don't recognize the type of connector.Can anyone identify this connector type for me?http://tomwade.me/tw/power_supply/ThanksTom

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: October 26, 2014, 07:48:57 pm
content: Bog standard MTA-100 or MTA-156?http://www.digikey.ca/product-search/en?s=4418&s=4419&FV=fff40016%2Cfff802f3&k=MTA&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=100
Power Supply constant current sink bulk capacitance application - Page 1
Forum section: electronics / projects

author: dtewksbury
author_rank: Newbie
timestamp: April 14, 2014, 10:29:42 am
content: Hello everybody, this is my first post on this forum.I thought I would share with you all a problem I am facing with one of our products we are developing, and the solution I came up with.The problem is that our application requires that we have large bulk capacitors across the output of our DC-DC converters, and by doing this we are pushing the converters into current limit every time the units is switched on. The engineers from the company supplying these converter modules were not happy with this situation.So I was sitting thinking about the the problem for a while and came up with the idea of having a sequenced start up circuit that would apply the output capacitance in a controlled way after the converter had stabilized. Unfortunately there is no adjustable soft start capability with these modules, and they are very expensive and we don't want to damage them.So I designed a circuit that after a pre determined delay, will apply a constant current sink to the zero volt side of the output capacitors and charge them until they are at rail voltage, at which time they are clamped hard to the rail.The circuit ended up being surprisingly simple, and as far as LTSPICE goes, works perfectly. I even simulated the load that our product put on the supplies to make sure there are no nasty surprises. At the time of writing this I am still waiting for the components to arrive from Digikey so I can bread board it and see it's performance.I have been watching a lot of Dave's videos and as a result this is my first LTSPICE simulation. I tried LTSPICE because Dave uses it and because I have been having a lot of trouble with the simulator I was using in the past.I will attach the LTSPICE file, so that anyone who is interested, can have a play for themselves.I hope this may be interesting, or even better still, useful for someone out there, and if Dave sees it, maybe he will find the way I did the constant current, without a current sensing element, quite neat.Note I added a .doc extension to the file that will need to be removed. I am not sure if I am violating any rules here. But the .asc extension was not supported. I am sure the moderator will remove it if it is not allowed, and in that case I will not do it again. Otherwise it would be nice to be able to share designs.
Power supply conversion for a simple analog project - Page 1
Forum section: electronics / projects

author: bsas
author_rank: Regular Contributor
timestamp: March 25, 2019, 06:24:41 pm
content: Hi all,Sorry for the very beginner/dumb question. I have a nice analog circuit that works fine for my needs (basically a white noise / pink noise generator) that works on +15V/GND/-15V DC power requirements and drains very little power (far less then 40mA). But, I was thinking about "boxing it" on a guitar pedal box and use regular guitar pedal power supplies, that are +9V/GND DC.So, is there any simple circuit I can do to make a (+9V/GND) to (+15V/GND/-15V) power rail?I was thinking about getting two "DC-to-DC" boost circuits and connect the (-)OUT side of one to the (+)OUT of the other and set each boost to 15V. Something cheap like this but I really don't know if that will work:https://www.amazon.com/gp/product/B07CNQPN94/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1Thanks!

author: Lee Leduc
author_rank: Regular Contributor
timestamp: March 26, 2019, 01:47:08 am
content: Do a search in Mouser or Digikey for a DC to DC converter. These are very common.Mouser has this. 9 volts in +/- 15 volts out. It may meet your needs.https://www.mouser.com/ProductDetail/RECOM-Power/RY-0915D?qs=sGAEpiMZZMvGsmoEFRKS8PNQK9Wr5ol%2FsW2YwSn9uUQ%3D
Power supply current regulation oddities - Page 1
Forum section: electronics / projects

author: madworm
author_rank: Frequent Contributor
timestamp: May 05, 2012, 07:12:51 am
content: I'm having some newly discovered issues (thanks to my new scope) with my old power supply. I've attached a photo of the analog part of it. It uses a TL084 quad opamp for the voltage and current control loops. The reference voltages are created by 2x 8-bit DACs (not shown), which themselves are controlled by a microcontroller. It takes care of the user-interaction.Issues discovered so far:* about 10% voltage overshoot when the output is activated (via relay) - this would kill 3.3V devices.* massive current overshoot, the current control loop seems deliberately slow.I've played with the relevant capacitor a bit (C26, top right opamp). If it is removed altogether, the thing never gets out of over-current mode once entered. Replacing it with 22pF makes it unstable. I will have to get a 5pF-ish trimmer cap. to experiment further.The way the over-current limiting is implemented here seems somewhat flawed to me. The time it takes to kick in is way to long and it also depends on the set-current. For low values (say 20mA) it takes quite a long time on a human timescale until current is finally limited.See the attached traces. The colors match the dots in the schematic.I'm not actually thinking about fixing or redoing the control circuitry at all, I'm just playing with it. Maybe there are some simple things to improve its behaviour. I thought about adding an external module to compensate for its flaws, but getting an all new power supply sounds more attractive. This things is about 20 years old btw.
Power Supply Design - Page 1
Forum section: electronics / projects

author: Poorly Calculated
author_rank: Contributor
timestamp: November 04, 2018, 06:57:30 pm
content: I am in need of some assistance for a proper power supply for my project. I am using a Linear Technology LT6207 quad-op amp IC. I will be using the YPbPr to RGB "Typical Application" example provided in its datasheet, found here:https://www.analog.com/media/en/technical-documentation/data-sheets/620567fc.pdf.The example circuit shown has a +5V and -5V supply. At first, I thought I would try out two 100kOhm resistors in series to divide some V. Then I'd set a reference ground to be between the two resistors, giving me +V/2 and -V/2. Then I'd add some smoothing capacitors and a 7805 and 7905 regulator to each output respectively. But here is where another problem comes up, the only usable voltages I can find (in the tube TV this is going into) are 120V AC, 165V DC, 12V DC, and 5V DC. Using my voltage division method won't work with the 12V or 5V because the dropout voltage of the regulators I want to use are too high to work with +6V and -6V. Also, the 165V DC is too high and will definitely destroy my regulators. And I don't want to mess with 120V AC if I don't have to.So I am kind of stuck between a rock and a high voltage place here. Do I just buy an off-the-shelf solution? Or do I use a DC-DC converter? Any and all comments are greatly appreciated.

author: Zero999
author_rank: Super Contributor
timestamp: November 04, 2018, 09:14:55 pm
content: Schematic?The problem with using resistors to divide the voltage is the output impedance is equal to the values of both resistors in parallel, which will be 50k in this case. It won't be an issue if the potential divider is being used to bias an op-amp's input, but it won't work for an appreciable load.

author: spec
author_rank: Frequent Contributor
timestamp: November 04, 2018, 10:28:17 pm
content: Quote from: Poorly Calculated on November 04, 2018, 06:57:30 pmAlthough you do not wish to mess with 120V AC mains, considering the other options that you mention, that is exactly what I would advice. But you would not have to do much messing with 120V.I would recommend getting two 5V off-line 120V isolated switching power supplies, which are available quite cheaply from a number of sources, including ebay.You then wire the 5V DC outputs to give you two nice, +&- 5V supply lines for your high frequency amplifiers.This makes for a modular approach which is fairly independent of the circuitry of the mother unit.I don't know how much experience you have with high frequency work, but just in case be advised that layout decoupling, screening are critical to make high frequency circuits even work half decently.And ground loops and cross coupling are major problems. But, by using isolated independent supplies it is easier to minimize these problems.If I am telling an old hand at HF techniques the obvious- my apologies.
Power supply design approach - Page 1
Forum section: electronics / projects

author: Red_Micro
author_rank: Regular Contributor
timestamp: February 07, 2020, 02:51:25 pm
content: Hi,I want to design a power supply with these specs for metering purposes:Input voltage = 100-600VAC three phase (RMS line to line)Output voltage = 48V and 3.3V/200mAI'm looking into two approaches: A cap dropper and a flyback SMPS. Flyback has higher efficiency at the expense of higher cost and complexity. Cap dropper is kind of a cheaper option but capacitors at this high voltage are also expensive.I'd appreciate any suggestions on trade-offs.

author: moffy
author_rank: Super Contributor
timestamp: February 08, 2020, 09:16:15 am
content: Why the three phase input? You only need a single phase.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 08, 2020, 09:31:29 am
content: For the low power one can likely use just a single phase. However if available anyway it is only 2 more diodes and fuses to save on the filter cap.The flyback converter would also need high voltage capacitors of some kind, though possibly a little less. The more tricky part could be the semiconductor: 600 V AC results in up to som 900 V DC worst case. So it would need really high voltage switches (e.g. 1500 V types).

author: trobbins
author_rank: Frequent Contributor
timestamp: February 08, 2020, 10:32:48 am
content: The OP appears to only have 3 phases, no neutral, so the minimum 'single phase' is to use a 'floating' phase-to-phase level that can get to 600Vac.Is a mains frequency transformer out of the question for some reason?

author: David Hess
author_rank: Super Contributor
timestamp: February 09, 2020, 01:23:03 am
content: Wide input range switching regulators exist but a 1:4 ratio is typical. Some support an even wider input range but finding a suitable one would be a problem.The usual problem is preventing or handling the transition between discontinuous and continuous conduction modes as the input voltage and output load current vary over their entire range because frequency compensation requirement are variable in discontinuous mode where the duty cycle varies. This can mean using a much larger inductance to prevent discontinuous mode operation, which compromises performance, or using a topology like constant off-time which does not care.For safety reasons, it might be acceptable or desirable to use a power transformer for input isolation *before* the switching regulator despite the extra weight and cost. Some old test equipment did this like the Tektronix 2225 series of oscilloscopes even though off-line switching regulators were available at the time.
power supply design help - Page 1
Forum section: electronics / projects

author: majorkuso
author_rank: Contributor
timestamp: June 20, 2015, 04:59:54 pm
content: I am wanting to design a power supply for my coherent 12w laser module I was planning on using a pc power supply to power it and using a couple of lm338 regulators to supply an adjustable voltage with current limited to 8 amps.

author: jeroen79
author_rank: Frequent Contributor
timestamp: June 21, 2015, 05:53:35 pm
content: I see no question in your post. What is it exactly that you want help with?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 22, 2015, 02:20:00 am
content: Quote from: jeroen79 on June 21, 2015, 05:53:35 pmWhich eye to vaporize first?

author: jeroen79
author_rank: Frequent Contributor
timestamp: June 22, 2015, 03:11:59 pm
content: Quote from: Alex Eisenhut on June 22, 2015, 02:20:00 amBetter put up a sign:
Power supply design question 2 / 2 - 120V conversion - Page 1
Forum section: electronics / projects

author: metertech58761
author_rank: Frequent Contributor
timestamp: August 04, 2024, 04:55:14 pm
content: Here's the second question I have on this circuit.Before continuing, as we're talking about mains voltage, I want to make it clear I have NO intention of doing ANY modification, but I want to get an idea of how it would have been done.There is NO chance of the original manufacturer documentation surviving, as the original manufacturer sold the division that made this product in the late 1990s, a few years after they officially moved this particular product into 'end of life' status. Any information the buyer did not take in the transaction would have been discarded when the original manufacturer moved into a newer facility. Even so, the buyer did a major housecleaning some years back and purged any information on long-obsolete equipment (and their last remaining examples of same).Anyway, if you look at the schematic, you can see it was designed to be powered from a 240V 3-wire circuit, the default voltage provided to residential services in North America.Line 1 would connect at E22, the neutral at E21, and Line 2 at E24.However, there are a few cases where the customer would have an older 120V 2-wire circuit, and looking at this circuit, it appears that this could be reconnected to configure the unit to work properly with just one hot wire and the neutral.PW1 is a trace that could be severed if necessary, E11, E19, and E20 are pads on Panel B and D that are not connected. Also, W1 and W3 are jumper wire pads, with pin 1 being the larger of the two pads.I could probably reason this out myself, but I want to see if anyone else would be able or willing to try and suggest how this would have been done.Again, I have no interest in trying to do the conversion as some of the bespoke coils change value for 120V operation (I know this as I was looking up something else and chanced across a notation of parts values for the 120V / 240V versions of this product). I just want to know how it would have been done.
Power supply discharge at power off. - Page 1
Forum section: electronics / projects

author: DavidDLC
author_rank: Frequent Contributor
timestamp: September 21, 2010, 05:38:29 pm
content: I have a power supply based on the LM regulator series, when the power supply is turned off, it takes long time to discharge.I have a voltage panel meter connected to it, and don't like the fact that the LCD will go off after some (long) time after shutting down the unit.So is there a technique to automatically discharge faster the power supply when turned off ?Something I can add to the power supply output (without modifying the existing PS), but of course the idea is that when the PS is on this circuit will present a small load to the PS.Please comment or suggest.

author: Zero999
author_rank: Super Contributor
timestamp: September 21, 2010, 06:00:07 pm
content: Use a double pole switch, one pole for the mains and the other for the DC side but make sure the switch has adequate isolation between poles.

author: DavidDLC
author_rank: Frequent Contributor
timestamp: September 21, 2010, 06:20:10 pm
content: Good idea, but I want to avoid changing the current PS and would like to add something to the output.I also would like to avoid mechanical devices like relays or switches.

author: Time
author_rank: Frequent Contributor
timestamp: September 21, 2010, 06:23:45 pm
content: Why would you want to avoid a relay? Thats the typical solution for this situation, that or the switch as mentioned.

author: Zad
author_rank: Super Contributor
timestamp: September 21, 2010, 07:05:19 pm
content: Surely a 10k or so bleed resistor will drain the caps in not-very-long without massively compromising the drive current?

author: Unknown
author_rank: Unknown
timestamp: September 21, 2010, 08:11:48 pm
content: Quote from: Zad on September 21, 2010, 07:05:19 pmThis also seems the obvious solution for me. Especially since this doesn't look like an application that need to conserve every last uA.

author: Zero999
author_rank: Super Contributor
timestamp: September 21, 2010, 10:37:38 pm
content: A small incandescent lamp is probably idea as it will also function as an additional power on indicator which will prove the meter is working properly.

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 22, 2010, 12:42:39 am
content: Use a watchdog chip to monitor the transformer secondary. Could be as simple as a charge pump based on a few discrete capacitors and diodes.

author: Simon
author_rank: Unknown
timestamp: September 22, 2010, 06:44:57 am
content: just fiddle with some resistor values and see hos small a value you need to discharge it in the amount of time you want, then see if your happy with the current draw of that resistor when power is meant to be on
power supply dought - Page 1
Forum section: electronics / projects

author: electros6
author_rank: Regular Contributor
timestamp: October 19, 2014, 02:14:17 pm
content: Hi guys,I tried to do study the HP E3620. So I build the circuit and did various test and I work like a treat. So I tried to do the next version using DAC and microcontroller just like agilent E3634A . I got one dought whether the reference voltage is set based on the calculated value or any feedback loop is used to control the DAC . what I am trying to say is suppose consider in order to set 5V out if DAC to set 1V , whether 1V is set directly or feedback loop is used to monitor the out value and set the DAC value accordingly.why I ask this is if the DAC value is set directly due to aging the calculated value may differ, right?

author: Marco
author_rank: Super Contributor
timestamp: October 19, 2014, 02:45:24 pm
content: Sure, the DAC can drift ... but so can the ADC.
Power supply fails to start - Page 1
Forum section: electronics / projects

author: itdontgo
author_rank: Regular Contributor
timestamp: March 09, 2016, 11:46:29 am
content: Hi,I'm a little baffled by this issue. Initially this prototype board we have worked fine. It then appeared to struggle to start but touching the soft start capacitor made it run. Eventually though it would not reliably start regardless unless you started it at 30V! This is the same circuit we have built many times although in the past it has had a different PCB layout. The main supply chip is the AOZ1284http://www.aosmd.com/res/data_sheets/AOZ1284PI.pdfWhen it runs it's a nice power supply with low noise. All of the main parts have been changed. When we changed the coil it worked perfectly but this had nothing to do with the coil.We accidentally knocked the boot strap capacitor off. It always starts with this removed, however, runs noisily at high voltages but does not take excessive current.I'll be honest I don't understand the issue. The general PCB layout is good when it runs.

author: Apollyon25_
author_rank: Regular Contributor
timestamp: March 13, 2016, 08:59:48 pm
content: Sounds like you took a perfectly good design and changed too much of it.Schematic, PCB??You have all the keys to answer this - you've mentioned many of them.

author: rx8pilot
author_rank: Super Contributor
timestamp: March 13, 2016, 09:15:17 pm
content: post the schematic and all layers of the pcb. It's almost always thelayout. Few people give enough credit to the impact of parasitics of the PCB. They will stop any converter.Sent from my horrible mobile....
Power supply filtering for a µA range amplifier  - Page 1
Forum section: electronics / projects

author: PeterFW
author_rank: Frequent Contributor
timestamp: March 19, 2015, 04:20:35 am
content: Hello!Before is set out and stumble right into the next hole id would like to ask if someone has allready done something similar and might share the outcome.I build a PIN diode radiation detector using the design from opengeiger.de and modified it slightly.The circuit runs fine of a 9V battery and only draws about 5mA.Everything is stuffed inside a shieldet, grounded and blessed enclosure, there is a basic LC filter on the input.The circuit runs ok of my linear bench power supply, there is occasional false triggering caused by noise, at least that is what my scope tells me.Now i would like to explore the possibilty to run the circuit from a boost regulator of a single cell, i hate 9v blocks.This is a bad idea since miniscule noise on the power supply will wreak havoc with the amplifier and comparator.The DCDC converter and the detector would be in two seperate enclosures.My first idea is a ferrite on the cable that connects both units and a PI filter on the power input of the detector matched to the switching frequency of the DCDC converter.Followed by some smoothing capacity, then a decent linear regulator and some bulk capacity after the regulator.Anny thoughts?Greetings,Peter
Power supply for a tube based car radio - Page 1
Forum section: electronics / projects

author: orbanp
author_rank: Regular Contributor
timestamp: February 07, 2017, 06:49:47 pm
content: Hello Everyone,I was asked to restore/convert a tube based car radio.So far I am collecting information on the best way to accomplish this.Originally the radio was powered from a 6V positive grounded supply, using a vibrator for the B+ supply.The car it would be used in has the electrical system converted to a 12V negative grounded system.The radio is a Stewart-Warner R-3271, the car is a '40 Packard.The owner is fine with a non-authentic restoration, though I will save all the original parts removed/replaced.It looks like the vibrator part of the radio is toast, the transformer has spilled its guts, the tar spilled from the sealed transformer. My guess is that one of the contacts of the vibrator shorted, got welded shut, and that overheated the transformer.So far I have not made any measurements, repair, or disassembly of the radio, just visual inspection.As the 6V vibrator based HT system can not be used, I am thinking about building a modern DC-DC converter for the B+ supply.The filaments can be rewired for 12V, there is an even number of 6V filament tubes with equal filament currents.The B+ requirement is about 250VDC, 80mA to 100mA.I have been looking at resonant Royer converters, as they have low noise. Linear Technology has a number of excellent application notes on these by the late Jim Williams.I have also came across ready made units on eBay that would fit the bill at the first look, one like this:http://www.ebay.ca/itm/DC-DC-8-32V-to-45-390V-High-Voltage-Boost-Converter-ZVS-Step-up-Booster-Module-/322374615632?hash=item4b0f064250:g:DuUAAOSw5cNYZm5VI would never be able to beat the price and build quality of such a unit, but I am curious about the circuit and the noise it would generate.Anyone familiar with the design of that unit? - TI has a number of app notes about ZVS-converters.The DC-DC converter unit will be located outside of the radio, probably next to the head unit, and I could probably shield it and filter the inputs outputs.I would appreciate any comments and suggestions regarding this conversion!Thanks, Peter
Power supply for Class D amplifier - Page 1
Forum section: electronics / projects

author: Adgj533
author_rank: Contributor
timestamp: March 19, 2019, 03:40:35 am
content: Hello guys, I am trying to build a class D amplifier at home on a breadboard(schematic attached). I am going to do this on a PCB as well but I used a breadboard to test it and see how it works etc. My question is I am having trouble connecting the power supply to this. I built the power supply circuit (2nd schematic) and I am not sure how to connect it to my power supply. The PSU I have is this: (the model I have is 3 A in series and 6A in parallel, this model has higher current but everything else is the same):https://www.amazon.com/Precision-Triple-Output-Linear-Quadruple-Display/dp/B00B03X90YI used + terminal of one side and put the - to the ground to get +30V and the other side I did the opposite to get -30V. Is that how I am supposed to do it? Also my PSU can only do 3 Amps max in series, is that enough to power this amplifier?Thanks for taking the time to read this.Any help is greatly appreciated
power supply for electrostatic corona discharge separator - Page 1
Forum section: electronics / projects

author: kriswillems
author_rank: Newbie
timestamp: April 15, 2024, 03:47:54 am
content: Hello all, this is my first post, so please forgive me if I get some things wrong.My son is trying to build an electrostatic separator to separate beach sand and microplastics for a school project.He has 3D printed some parts and built a prototype, which kinda works in lab circumstances.As a power supply he uses a 20KV power supply used for arc based cigarette lighters. (it's a 2 dollar tiny Chinese thing).This supply is lithium ion battery powered an delivers 20KV AC.Actually we don't know how much volt it generates because we don't know how to measure it. But it manages to generate a plasma arc on corona wire electrode starting from a distance of about 1.2 cm.He rectifies the AC of the supply using a single microwave diode, without capacitor.We have the following questions:- The output of an electrostatic cigarette lighter is AC. It is not deadly when touched. But does it become deadly when being rectified to DC?- Does using a bridge rectifier instead of single diode actually improve the amount of corona discharge?- Does the efficiency of the corona discharge increase when we add a smoothing capacitor to the rectified output? (We don't want arcing/plasma, just ionization)- If we add a capacitor, what is the maximum capacitance we may add that won't kill you when touching the supply, assuming the supply is 20KV-DC. The supply voltage collapses under load (a human touching) but the capacitor might hold enough power to kill someone....- Are there any better high voltage DC voltage power supplies for sale that are better for the purpose, that don't kill you?- How do we measure high DC voltages without very expensive equipment?