hybridfree/eevblog-posts huggingface dataset:
DC Power Source for PWM Motor Controller - Page 1
Forum section: electronics / beginners

author: TimeBandit
author_rank: Regular Contributor
timestamp: March 02, 2022, 11:48:12 pm
content: I'm new to PWM Motor Controllers. I see many reference using a battery(s) for the DC source. Any reason an SMPS can't be used, assuming the output voltage is in the range spec'd by the controller, and the amps are sufficient for the motor in question?

author: jwet
author_rank: Frequent Contributor
timestamp: March 16, 2022, 03:28:30 pm
content: A DC power supply Linear or Switcher would work. There are a few things to watch out for though.Batteries are a pretty nice source and are unconditionally stable with any load, you may wear them out a bit quicker with big pulsed loads but they won't misbehave. Regulated power supplies aren't like this- they can overshoot and in extreme case oscillate with squirelly loads. I'm not trying to scare you but weird things can happen.A run of the mill SMPS(Chinese/Ebay) might not like having its output hammered on by a rapidly pulsing inductive load that a PWM would give it. This is actually a common torture test for power supplies. I would add a large capacitance to the output of the switcher with a PTC device in series to limit the inrush current to the caps to something like the max rating of the supply. If the supply makes noise when you turn it on, there is likely too much inrush. Once these caps are charged, they will handle the fast edges and the supply will only have to refresh their charge and won't have too much trouble. Be a bit careful with layout too- don't have a lot of excess wire wiring around with high frequency PWM signal on it. The wires have inductance and will try to store the current spikes and generate voltage spikes, etc. It would be good to look at the supply output with a O'scope if you have one. Measuring inrush current with a low value shunt would be good too.Another option which is probably cheaper is a unregulated linear power supply. This is just a transformer, bridge rectifier and bulk caps like above. Get a transformer with an AC output of about 80% of your required voltage, add a bridge and a cap and then use this to run your PWM. This kind of supply is common for pwm stepper drivers and audio amps- you don't need precision regulation, the pwm speed control does this basically and the voltage regulation stuff actually gets in the way. There are online calculators for designing these circuits- google around a bit. The better ones will even show you what the ripple etc will look like on a scope trace.Good luck,
DC Power Supply Amperage  - Page 1
Forum section: electronics / beginners

author: sci4me
author_rank: Regular Contributor
timestamp: March 07, 2015, 05:18:49 pm
content: Hi all. I am working on a project that will use about 4.8 amps of power. I am currently looking for a power supply for it. I want something like this:http://www.adafruit.com/product/658.My question is how much extra is acceptable? I assume that that PSU is pretty overkill right? Would 5 or 6 be okay?

author: Zero999
author_rank: Super Contributor
timestamp: March 07, 2015, 07:36:19 pm
content: Yes more current is fine.The only possible problem is if there's a short circuit and the wiring is too thin to take the current, in which case a fuse is a good idea.

author: rdl
author_rank: Super Contributor
timestamp: March 07, 2015, 08:13:00 pm
content: Often the cheaper switch-mode power supplies will have "optimistic" specifications. I have for example, a 9 volt 1 amp supply that works pretty well up to about 700 mA, but trying to draw much more than that causes the voltage to drop significantly. I would say using a 10 amp rated supply to get 5 amps is a probably a good place to be.

author: AmmoJammo
author_rank: Frequent Contributor
timestamp: March 07, 2015, 09:15:09 pm
content: I spent an hour trying to get an oldish touchscreen LCD panel to do anything!It would power up, but never display an input signal..... I replaced all the electrolytic capacitors, as the screen was getting on a bit, and had spent a fair bit of its life in a vehicle...Turned out, the 12volt, 2amp power supply was dropping to 9volts with a 1amp load, so the screen was never powering up properly...Tried it with a 12volt, 1.5amp supply, and it worked fine...
DC power supply mp710086 - problem to keep output ON by default - Page 1
Forum section: electronics / beginners

author: nudist
author_rank: Newbie
timestamp: January 23, 2022, 06:51:38 am
content: Hi,I am using this new DC power supply mp710086. Since there are frequent mains power failures, at every reboot it needs a manual operation to start the output by pressing the ON button. Is there a way to to keep output ON by default after a reset of mains input supply.Please suggest,Thanks a lotV

author: Manul
author_rank: Super Contributor
timestamp: January 23, 2022, 02:46:28 pm
content: I'm not sure if it is a good idea to start messing around with the internal circuit. If it can be controlled externally by RS232, just add some arduino thingy with RS232 converter to send the command. As a bonus it would allow you to do much more, not just activating a channel. If your ever need more.
DC Power Supply Question - Page 1
Forum section: electronics / beginners

author: Gooch
author_rank: Newbie
timestamp: October 26, 2013, 11:57:29 pm
content: Hi everyoneI am new here been watching Dave's video's and reading posts I play around with diy audio build a few things now and want to up my game and learn more about electronic. I was given a Lambda LP412A-FM power supply I know it's kinda dated piece of equipment it seems to work ok. So my question is I was testing a zener diode I set my voltage to 20V and about 10mA current I put a 1k load resistor in line on the negative rail under load it's dropping about 6 volts is this normal.ThanksDave

author: Unknown
author_rank: Unknown
timestamp: October 27, 2013, 12:36:34 am
content: Lambda made (and makes) excellent power supplies, so I see nothing wrong with starting with this power supply. Apart from obvious limitations like no computer control and only a single channel this power supply should perform very similar to new power supplies, and is better made than the cheap power supplies that go under various names often sold new on eBay. If you didn't get a manual, you can get a PDF copy atArtekManuals, but I don't really see a reason to need this manual unless you need to repair it or want to use the remote programming / sensing connections at the back.According to Ohm's law, putting 20 V across a 1 kohm resistor would cause 20 ma current to flow. You don't mention the zener voltage, but from your description I assume it would be about 5V, so the same argument would still apply (15V across 1 kohm would mean 15 mA would flow, more than the 10 mA limit). Since you limit the current to 10 mA, the power supply will reduce the voltage to keep the current under 10 mA. Increase the current limit and you should see that the voltage remains stable under load.

author: Gooch
author_rank: Newbie
timestamp: October 27, 2013, 01:15:22 am
content: Thanks for the reply almThats good to know about the power supply the zener's where 9v and one 6v I build this preamp kit a few years ago and just couldn't get it to work I got tiered of pulling parts of the PCB hoping it would work so I put it a side. Now I have decided to give it ago again so I been trying to really wrap my head around it and under stand it I am not an EE this is also to only kit I built where I didn't source the parts myself so I might have had a bad part from the beginning thanks again.RegardsDave
DC Power Supply Recommendation - Page 1
Forum section: electronics / beginners

author: bsnbipen
author_rank: Newbie
timestamp: May 08, 2024, 03:07:37 pm
content: I have an AMP that requires a supply of +_100V and 0-2A. What would be a good go-to budget power supply?

author: themadhippy
author_rank: Super Contributor
timestamp: May 08, 2024, 03:40:54 pm
content: what makes you think you'll get a different reply to those you received on yesterdays post asking the same question?https://www.eevblog.com/forum/beginners/a-not-too-expensive-dc-power-supply/msg5488645/#msg5488645

author: Simon
author_rank: Unknown
timestamp: May 08, 2024, 07:52:56 pm
content: Duplicate threads just annoy everyone and eventually you get banned.
DC power supply salvage - Page 1
Forum section: electronics / beginners

author: martik777
author_rank: Newbie
timestamp: May 22, 2014, 09:30:22 am
content: Got this from a colour laser. It has +12, -12 and 5vdc outputs which measure accurately on my meter. However, when I connect up a 10w 12v led it flickers (seems like 60hz flicker) draws about 900ma. Same flicker on the 5vdc line with a 1watt led. What could be causing the flicker?Thanks

author: potatogun96
author_rank: Contributor
timestamp: May 22, 2014, 05:03:20 pm
content: I would try adding some large capacitors on the outputs. However, this won't help if the output current is too low.

author: edpalmer42
author_rank: Super Contributor
timestamp: May 22, 2014, 05:26:32 pm
content: Some switching supplies require a minimum load before they start to work right. If this power supply was designed specifically for this unit, it could be expecting to see that specific load, or close to it. Sometimes the load only has to be on the main output - whichever one that is.Ed
DC powered device : is a fuse needed ? - Page 1
Forum section: electronics / beginners

author: ratatax
author_rank: Regular Contributor
timestamp: August 25, 2019, 08:18:05 am
content: Hello,I'm designing a pcb for a device that will get 12V DC from a power adapter. The power adapter itself is well protected against short circuits, over voltage and is certified in almost all countries.I'd like to know if a fuse is still needed on my 12V input. Would you put one ?I can tell my users to only use the provided adapter so I'm not faulty if they use a shitty one that catches fire, but I'd like to know what is the best practice here, what choice would you take for your project.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 25, 2019, 08:34:51 am
content: Best practices is to put a fuse if there is a risk to catch fire.The whole idea of having a fuse is to protect against firewhen things go wrong in unpredictable ways, so relying on the power supply protections is not good enough.Also, the "not my fault" approach if the customer uses a wrong power adapter will still hurt your product badly. If a single unit will catch fire, no matter the reason, people will find out and avoid your product(s) in the future or, someone else might make a product review and point out your product can set the house on fire. Not good for business.As an example, PC motherboards (DC powered) have fuses for the external connectors that carry enough power.

author: radiolistener
author_rank: Super Contributor
timestamp: August 25, 2019, 01:03:57 pm
content: If your power supply can provide high power, then fuse definitely must have.For 13.8 V 40-60 A power supply I also recommend to use thyristor over-voltage protection and reverse polarity protection, because if something will going wrong, such power may burn in fire even PCB of your circuit and make serious damage.The idea is that thyristor make short circuit in case of over voltage and take all power through self to protect your circuit.For example, BT152-400R can handle 200A for 10ms, which should be enough to burn out fuse:

author: Zero999
author_rank: Super Contributor
timestamp: August 25, 2019, 01:26:07 pm
content: Quote from: ratatax on August 25, 2019, 08:18:05 amHow thick is the cable?If the power adaptor can output a higher current, than the cable can take, before it cuts out or current limits, then a fuse is required.For example, suppose your adaptor is only 1A and the cable has a cross-sectional area of 0.52and insulation which can take 60ºC, then there's no need for a fuse, as the cable will be able to handle the short circuit current. On the other hand, if the power supply is capable of 15A, then you definitely need a fuse, as the cable will start to smoke, if there's a short circuit.
DC Protection circuit - Page 1
Forum section: electronics / beginners

author: braintree
author_rank: Newbie
timestamp: April 17, 2025, 09:20:00 am
content: Hi all,Can anyone help me understand what's going on in this circuit? Here's a Falstad linkhttps://tinyurl.com/2bds334yIt's supposed to do polarity correction, overvoltage & short circuit protection for a DC supply.I can follow the polarity correction easily enough, it just looks like a MOSFET rectifier, but I'm struggling to understand what's happening with the overvoltage & short circuit protection. I've been playing with it for a while, and I'm really stuck
DC PSU Design - Page 1
Forum section: electronics / beginners

author: echen1024
author_rank: Super Contributor
timestamp: September 02, 2013, 12:28:31 am
content: I need a good, linear based power supply design. I have a simple LM317 connected according to the datasheet, but I would like to improve it with a rotary encoder and error amplification, and constant current. Any suggestions and part numbers are very much appreciated. I mainly do digital, so this is not my domain.

author: c4757p
author_rank: Super Contributor
timestamp: September 02, 2013, 12:32:41 am
content: Dude, asking for linear power supply designs on an electronics forum is like asking for porn on the rest of the Internet. Search and ye shall receive results beyond your wildest dreams.

author: Paul Price
author_rank: Super Contributor
timestamp: September 02, 2013, 01:32:11 am
content: https://www.eevblog.com/forum/beginners/adding-current-regulation-to-a-variable-lab-power-supply/

author: peter.mitchell
author_rank: Super Contributor
timestamp: September 02, 2013, 02:32:59 am
content: Quote from: c4757p on September 02, 2013, 12:32:41 amProbably the single most accurate description i have heard.

author: BravoV
author_rank: Super Contributor
timestamp: September 02, 2013, 02:38:32 am
content: Quote from: peter.mitchell on September 02, 2013, 02:32:59 am+1 , and sig worthy too, done, new sig applied, c4757p, you're now famous !!

author: KJDS
author_rank: Super Contributor
timestamp: September 02, 2013, 08:52:40 am
content: Quote from: peter.mitchell on September 02, 2013, 02:32:59 am. ...and like a lot of porn, a lot of PSU stuff isn't very satisfying.

author: echen1024
author_rank: Super Contributor
timestamp: September 02, 2013, 02:11:38 pm
content: Quote from: KJDS on September 02, 2013, 08:52:40 amExactly. But I must admit, that was pretty funny.

author: 6502nop
author_rank: Regular Contributor
timestamp: September 02, 2013, 03:42:31 pm
content: QuoteWorse yet, following a link for a schematic or YouTube guide, and realizing that you've just clicked on the electronics equivalent to "Two Girls, One Cup".nop
DC pulse and current limiter - Page 1
Forum section: electronics / beginners

author: Darlington
author_rank: Contributor
timestamp: February 28, 2025, 05:22:55 pm
content: I am studying a constant current limiter so as to keep the current drawn by the LED constant.Everything works fine with a constant voltage generator, but if I try to see the behavior of the circuit with a pulsed DC voltage the graph shows me positive and negative spikes.I now assume that the spikes are due to the intervention of transistor Q2.How can I get a current limiter that is also good for limiting current with a pulsed DC generator?

author: Benta
author_rank: Super Contributor
timestamp: February 28, 2025, 09:47:47 pm
content: That circuit is potentially dangerous EMI-wise, it tends to oscillate in the +100 MHz region. There are several threads on this forum about the issue.A suggestion is that you replace Q1 with two 1N4148s in series, then it will always be stable.Also, increase R1 to 10 kohms or more.The spikes may also be related to too small a timestep in the simulation.This is the circuit I use myself. R2 is crucial, as it prevent the oscillations I mentioned above:

author: D2236
author_rank: Regular Contributor
timestamp: March 01, 2025, 04:10:40 am
content: Quote from: Darlington on February 28, 2025, 05:22:55 pmBe careful when doing your simulations. Quite often some of the default values for the pulse source is set to unrealistic values. For instance, look at the values for rise-fall times, and make sure it is not set to something silly like 1 ps. Take note that a good quality function generator used in university labs will have their fastest rise-fall times in the order of 10 ns. Try to evaluate your circuit with this in mind, and you should get better results.

author: Darlington
author_rank: Contributor
timestamp: March 01, 2025, 12:03:39 pm
content: I tried your circuit and it seems to work well. I followed your suggestions and actually the rise time and fall time were set to 10ps, changed them to more real values like 10ns and they seem to be fine. I also found a constant current settable led driver the PSSI2021SAY by NXP Semiconductors. I tried it in the simulation and it seems to work well even with a pulsed DC generator. Is this simulation reliable?What leaves me in doubt is that the on/off control and power supply are the same thing, while the datasheet suggests another configuration.In my case, actually the power supply acts as a control, if no current flows the generator will not work.What do you guys think?
DC- regulator - Y or X-class capacitor? - Page 1
Forum section: electronics / beginners

author: Tantalum
author_rank: Regular Contributor
timestamp: May 15, 2024, 02:25:20 pm
content: HelloIn the datasheet of an isolated DC-DC regulator module (not AC-DC!) is written that there should be a decoupling capacitor betweenthe grounds of both sides (C3). The value is indicated (470pF/2kV) but not the type of capacitor.Should it be a normal, a Y- or a X-class capacitor???(I have read somewhere that X capacitors are for differential mode EMI and Y for common mode EMI)Thank you

author: exmadscientist
author_rank: Frequent Contributor
timestamp: May 15, 2024, 05:33:51 pm
content: X and Y are safety classes for capacitors that touch mains. In summary, Class Y is required for capacitors that go mains line to protective earth. Class X (or Class Y, Y can always be substituted for anything lesser) is required for mains line to line.If you don't have mains involved, you don't need X/Y caps.(The idea behind this is basically that lightning and giant industrial motors and rogue squirrels and basically all sorts of things are found on the mains. So mains capacitors need to be very strong to withstand that stuff. It's not about the voltages or the currents. It's about the raccoons (the pulsed, very-short-duration, single-event raccoons). No mains, no mains rating needed. But it never hurts, it's just big and expensive.)

author: Tantalum
author_rank: Regular Contributor
timestamp: May 17, 2024, 03:18:26 pm
content: Thank you for the explanation

author: soldar
author_rank: Super Contributor
timestamp: May 17, 2024, 05:14:08 pm
content: X Y caps

author: Zero999
author_rank: Super Contributor
timestamp: May 17, 2024, 06:34:10 pm
content: What are the voltage ratings of the DC:DC converter?It might not be for mains, but it's still possible a Y capacitor is required for C3. For example, if the input voltage is >120VDC, or the isolation voltage rating is >120VDC, a Y capacitor is required for safety reasons, just like on mains.

author: Tantalum
author_rank: Regular Contributor
timestamp: May 18, 2024, 12:55:32 pm
content: 24VDC -> 5VDC
DC signal condititoning - Page 1
Forum section: electronics / beginners

author: Algojervia
author_rank: Unknown
timestamp: November 02, 2016, 10:52:46 am
content: Hello there.I have been working a small circuit that's just two 555 timers acting as a servo motor controller and that works great but now I want to control it via a NTC resistor. As you can see in the schematics bellow in my latest try I use an op-amp as a comparator and that in turn manipulate the voltage of pin 5 of the second 555 timer via the pots R7 and R8 that set the upper and lower voltage level. This works OK but can get a bit hysteric when the temperature changes slowly, making the servo go back and forth like crazy. I don't think this is particularly bad for the motor but it is not the nicest design. And what I really wanted to do was to make to servo open gradually over a span of a few degrees.And thereof the title but do any of you have a completely different design, i'm interested as along as it does not involve a µC. If I have a signal from a voltage divider of a NTC I can easily clip the voltage level with a diode but how do I set a lower voltage limit without distorting the signal. So I have a input signal that can swing between something like 1-4 volt but I'm only interested in the range of 2-3 volt and when the in signal is higher I wan't it to cap a 3 volt and when it is lower I want it to stay at 2 volt. I also want to be able to adjust the max and min levels. I think the problem I run into is that there is a lot of information on mixing ac components of a signal but I can't find anything about this type of DC mixing, maybe it is so trivial it is not worth a note? Also I do know how to clip the upper part but my attempts to set a minimum has only resulted in me adding a minimum level to the input signal instead of superimposing it.//A

author: Ammar
author_rank: Regular Contributor
timestamp: November 02, 2016, 11:21:03 am
content: A completely different design could involve an ADC connected to an FPGA. Doesn't even use a uC

author: Cliff Matthews
author_rank: Unknown
timestamp: November 02, 2016, 11:29:02 am
content: Maybe it's just me, but that schematic needed some help.. Here ya go!

author: Ian.M
author_rank: Super Contributor
timestamp: November 02, 2016, 03:10:08 pm
content: That's a grossly over-complex circuit. Ignoring passives, you only need one 555 and a couple of steering diodes to produce a voltage controlled servo signal, and to make it thermistor controlled, simply add a single supply rail to rail opamp, configured as an inverting amplifier, with the thermistor in a bridge feeding its inputs. The amplifier gain sets the transition range and the resistor in series with the thermistor sets the midpoint. When the output is railed or below 1/3Vcc it will have no further effect on the timing. If the servo movement is in the wrong direction, swap the thermistor and the resistor in series with it in the bridge. See attached LTSPICE sim for details.
dc sweep convergence issue for cmos inverter  - Page 1
Forum section: electronics / beginners

author: promach
author_rank: Frequent Contributor
timestamp: January 13, 2019, 11:24:53 am
content: I am having some convergence issue with DC sweep for a CMOS inverter.To duplicate the exact issue, see the following log as well as the attached netlist files, together withmodelcard.nmosandmodelcard.pmosI have tried various suggestions online (such as bypassing .op analysis , using smaller dc sweep step, use .ic initial condition, add parasitic resistance to circuit nodes), but those do not help in my case.ngspice run logQuotetest_CMOS_Inverter.netCode:* gnetlist -L ../.. -g spice-noqsi -o test_CMOS_Inverter.net test_CMOS_Inverter.sch* SPICE file generated by spice-noqsi version 20170819* Send requests or bug reports to jpd@noqsi.comX1 Vin vout INV1Vs Vss GND 0VVin Vin GND AC 1Vd Vdd GND 'SUPPLY'V_IP_out Cout vout DC 0VR2 GND Vin 100GR1 GND Cout 100GCout GND Cout 1n.PARAM SUPPLY=3.3v.options TEMP=25.IC v(Vin)=1.65 v(Vout)=1.65.MODEL n1 NMOS.MODEL p1 PMOS.GLOBAL Vdd Vss.INCLUDE CMOS_Inverter.net.controlsave all @m.x1.m1save all @m.x1.m2save all @m.x1.m1save all @m.x1.m2*opprint alldc Vin 0 Vd 0.01ac lin 100 1 10Glet Gm=(i(v_ip_out))/Vinplot Gmprint Gm > Transconductance_of_CMOS_inverter.log.endcCMOS_Inverter.netCode:* gnetlist -L ../.. -g spice-noqsi -o CMOS_Inverter.net CMOS_Inverter.sch* SPICE file generated by spice-noqsi version 20170819* Send requests or bug reports to jpd@noqsi.com.subckt INV1 2 1*M2 1 2 Vdd Vdd P1 l=0.4u w=3u m=25M1 1 2 Vss Vss N1 l=1.2u w=3u m=25*.ENDS
DC Swich mode on/off - Page 1
Forum section: electronics / beginners

author: kasparbp
author_rank: Newbie
timestamp: January 10, 2015, 09:48:28 am
content: HelloI am trying to design a PCB which have both a LDO and a switch mode DC-DC converter (MAX1688), I wan't to preserve as much power as possible so I want to shutdown the switch mode converter most of the time.According to the datasheet I can shut the switch mode supply off by driving the ON pin low on the IC, so thats easy, however my atmega that are controlling the supply is running on 3.3v from the LDO and the input to the switch mode supply is 3.6v.The datasheet says that the ON pin only need to get above 1.5v(or thereabout) to turn on, so the 3.3v should be enough, however I am concerned about current running back or something weird like that, I never mixed 2 different supplies like that.In all the schematics I have been able to find they always seem to tie the ON pin to Vin, so always on, no help there. The datasheet does not say much about the pin either.I have attached 2 solutions I am considering, are they any good? (i probably need to adjust the resisters but besides that is an transistor even needed?)

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 10, 2015, 02:26:01 pm
content: Input pins will not source current, so it is acceptable to drive an input (to a device on a higher supply) from an output (on a device with a lower supply). The second case is preferred. Probably 10k ohms would be fine for a pull-down.Tim

author: RR
author_rank: Contributor
timestamp: January 10, 2015, 09:01:23 pm
content: That N mosfet will not work like that. Dont forget that for switching its voltage between gate and source of mosfet not just gate-gnd. And 1m is what 1mili or Mega? Anyway just driving it from mcu with pulldown should be okay.

author: kasparbp
author_rank: Newbie
timestamp: January 11, 2015, 07:50:44 am
content: Thanks guys, going with the pulldownLooks like the mosfet option was bad design either way, i will have to read some more on the subject before trying to use any of those/Kaspar
DC relay circuit - Page 1
Forum section: electronics / beginners

author: seanf
author_rank: Contributor
timestamp: March 13, 2025, 10:02:43 pm
content: Been looking at the circuit of a mechanical relay thats on a microcontroller based timer, and wondered about a few things.The top/centre arrow on the picture above. Is that simply a bridge/link to go over the other traces, or is there more going on inside that component?The right hand side arrow. That looks like a capacitor?Following the traces and checking continuity, it looks like there is a capacitor being used to isolate a 6VDC section of the circuit, from the rectified but unfiltered supply to the relay coil.I take it this only really works if you have enough ripple in the 6VDC section to allow flow via the capacitor? Or does it all rely on having an inductor in the circuit?I put together a mock-up with through hole components, with no relay coil and only a small load from resistors. Using a capacitor to isolate the DC section from the 100Hz section didnt give the same results when looking at the waveforms. If I change the capacitor to a zener diode I can create the DC section and a 100Hz section.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: March 14, 2025, 05:23:44 am
content: The answer to your first question can be discovered with a multimeter in continuity mode.

author: benj38
author_rank: Frequent Contributor
timestamp: March 14, 2025, 08:23:53 am
content: Your schematic makes no sense. I strongly suggest you retrace the circuit. As you do so, do not forget that this may be a multilayer board with invisible internal power/ground planes, and that vias may be hiding below the bigger components.Finally, yes, the right-hand arrow in your first image points at a capacitor.

author: BennoG
author_rank: Frequent Contributor
timestamp: March 14, 2025, 06:31:57 pm
content: my first guess was a reed relais or a optocoupler.After checking the height of the component, a reed relais is almost impossible.So probably a opto coupler.Benno
DC to AC with minimal components? - Page 1
Forum section: electronics / beginners

author: AmirTheGreat
author_rank: Unknown
timestamp: February 20, 2013, 03:56:02 am
content: Hey guys. this is my very first post on a forum.im trying to build a circuit that takes dc and drives an EL wire which needs AC. I asked a couple of teachers at my college and they told me i would need some sort of a chip to make the voltage oscillate. But i found that a disposable camera can do this with just some basic components. sadly I dont have enough knowledge to reverse engineer the circuit and i need some help explaining how it is generating the AC.

author: c4757p
author_rank: Super Contributor
timestamp: February 20, 2013, 04:22:20 am
content: Doesn't EL wire usually take a pretty high voltage? You can certainly do it with just transistors, but I wouldn't recommend it. Try getting some basic transistor oscillators running before you even think about making them generate high voltages.And learn from some of my early mistakes: Before you make any circuit that puts out high voltage, make sure you understand it very thoroughly -enough to understand what it's capable of if it malfunctions. That boost converter that's supposed to put out 200V for some Nixie tubes may well shoot above 500V if it's designed by an idiotbeginner, and bad things tend to happen when you're 300V too high...

author: c4757p
author_rank: Super Contributor
timestamp: February 20, 2013, 04:24:13 am
content: (well, it's a three-video series) does a pretty good job of explaining that camera flash circuit, if you're wondering about it.

author: AmirTheGreat
author_rank: Unknown
timestamp: February 20, 2013, 04:45:39 am
content: Thank you, That video is all i needed.and thanks for the useful safety tips
DC to DC buck converter inductor question. Square wave on output. - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: June 15, 2016, 12:08:48 pm
content: I have built a DC to DC buck converter on a breadboard, so none optimized lead lengths. I used the circuit attached. The chart, also attached, for deducing inductor values for 50V in and 24V out do not correlates though. I used what i have on the breadboard, a 680uH and a 1000uH. The 680uH gives the waveform superimposed on the output as in the scope photo also attached. I am using a x10 probe and the scope is not compensating for that, so multiply the levels by 10 please. Using the 1000uH I see a diminishing ringing sine wave also superimposed. How critical is inductor value, and what do people recommend I try? The 680uH is wound on a ferrite rod core, and I could remove some turns. It's rated at 1.5 amps DC. The 1000uH is wound on a toroidal core. I am seeing the square wave with a 50 Ohm load resistor across the output so about 0.5 Amps being drawn. That is about the maximum i expect the circuit that needs 24V to draw. I am not using the optional ripple filter. Thanks.

author: rs20
author_rank: Super Contributor
timestamp: June 15, 2016, 12:22:46 pm
content: So you have 20 volts peak-to-peak ripple? That's not really ripple anymore, that's just a raw switching waveform. Are you sure you're probing the correct part of the circuit? (Ground clip and probe leads either side of the 2000uF capacitor, after the inductor?)

author: tautech
author_rank: Super Contributor
timestamp: June 15, 2016, 12:31:32 pm
content: Often IC manufacturers haverecommendedinductors (brands/models) for various reasons including frequency and current ratings and you can "roll your own" inductors but saturation and efficiency also need be considered and optimised in a number of ways.Current probes and shunts can be handy to check the relationship between on times, frequency and saturation.Furthermore efficiency checks need current measurements (power analysis).If you're fortunate enough to have something that works well enough and componentry is not heating you might just go with it.

author: Chris Wilson
author_rank: Super Contributor
timestamp: June 15, 2016, 12:53:34 pm
content: I am an idiot, I had the probe clipped on the diode leg, the breadboard has 2 other circuits I wanted to keep upon it and it's all very tight. Scrub the above, the output looks fine given lead lengths and board capacities and stuff, sorry!!!!

author: damn_dirty_ape
author_rank: Contributor
timestamp: June 18, 2016, 03:25:57 am
content: If you're doing this to learn, try to take time to understand the two different operating modes of almost all dc-dc converters. You can be in either continuous or discontinuous conduction modes. If you increase the resistance high enough you should hit discontinuous, which behaves a bit differently on the scope.https://en.wikipedia.org/wiki/Buck_converter#Discontinuous_mode
DC to DC converter - Page 1
Forum section: electronics / beginners

author: JoeAtl30319
author_rank: Contributor
timestamp: August 10, 2012, 12:37:57 am
content: What is the point of a DC to DC converter if the input and output voltages are the same?

author: FenderBender
author_rank: Super Contributor
timestamp: August 10, 2012, 12:48:25 am
content: What do you mean? What application?

author: JoeAtl30319
author_rank: Contributor
timestamp: August 10, 2012, 12:53:22 am
content: Dave recently did a video where he used a 5 volt to 5 volt dc converter. I also see these in electronics catalogs. I just cannot imagine what these would be used for... If the output closely follows the source, what application do they have?

author: digsys
author_rank: Unknown
timestamp: August 10, 2012, 12:54:50 am
content: Quote from: JoeAtl30319 on August 10, 2012, 12:37:57 amHow else are you going to generate heat :-) ... jkIF you're talking about a FIXED Vin=Vout, then it is providing Isolation !! A very important quality for many projects.Otherwise, you probably misread the specs - the Vin is likely a RANGE of voltage, in which case you'd use itfor the conversion EFFICIENCY value (unlike a LINEAR regulator).

author: David_AVD
author_rank: Super Contributor
timestamp: August 10, 2012, 01:56:18 am
content: As digsys said, DC-DC converters come in isolated and non-isolated varieties. Some have more than one output too.The isolated ones are often (but not always) a 1:1 conversion scale. These are often used in conjunction with opto couplers to provide an electrically isolated section of the circuit.The non-isolated ones are more often buck (step-down) types where you want to provide a nice regulated voltage from some higher voltage. These are sometimes call POL (Point Of Load) regulators as they are used close to where the lower voltage is required.

author: Psi
author_rank: Super Contributor
timestamp: August 10, 2012, 02:19:09 am
content: There's also buck-boost dc-dc converters, you might see one that's 12V in and 12V out.If you look closely at the specs the input voltage will be a range, like 8V-15VThey're used to get a stable 12V from a 12V battery.Like for example in a car where the battery voltage could be as low as 8V while the engine is cranking or as high as 14.5V while the alternator is charging.
DC wire extension question using a different gauge. - Page 1
Forum section: electronics / beginners

author: lots o tots
author_rank: Contributor
timestamp: June 02, 2017, 12:55:38 pm
content: Hello alli have a peltier cooler that draws 11amps at 12volts. The wire leads are 6" long and only 22 gauge to my disappointment. I have checked out some wire charts online for DC power and the extension at 22 gauge would bring this near the capacity of the wire (especially since some of it will be embedded in insulation). I need to extend the 6" wires to a total length of 1 to 2 feet. unfortunatley desoldering the existing leads at the peltier is not an option.Can i use a thicker gauge wire closer to the power supply as i don't want to desolder the cables near the peltier?I have 16 gauge stranded lying around. Can i use the 16 gauge stranded to extend this wire to 1 or 2 feet?Do the extension wires need to be soldered to the peltier wires? I wanted to just use wire nuts if it is safe and no soldering if given a choice as this project is time senstive. I am not interested in aesthetic value for this project.Please let me know if this extension using a 16 gauge stranded wire with wire nuts and no solder is safe.Thanks

author: jeroen79
author_rank: Frequent Contributor
timestamp: June 02, 2017, 01:30:29 pm
content: 1 Yes2 look up awg table3 Possibly if it wont be subjected to vibrations, moisture, etc.But how much time will a properly soldered or crimped joint take?

author: P90
author_rank: Frequent Contributor
timestamp: June 02, 2017, 01:35:39 pm
content: I would solder and heat shrink the wires. Second option use butt crimp connectors.
DC005 for high current applications? Other plugs? - Page 1
Forum section: electronics / beginners

author: ivoras
author_rank: Contributor
timestamp: July 30, 2019, 01:48:09 pm
content: While looking at the construction of DC-005 and similar sockets (female side), it looks like there's pretty much a single point of contact for the current to flow at least on the outer layer of the plug.Would that kind of construction hold e.g. 5 A to 10 A of current (12 V)?Any other suggestions for an easy, wide-spread plug which could be used?

author: ledtester
author_rank: Super Contributor
timestamp: August 01, 2019, 11:19:12 am
content: This catalog page suggests that all of the low-voltage DC power jacks are rated 0-30V, 1-3A.http://www.peterparts.com/CatalogPages/65/1461.pdfFor high current you might consider XT-30 or XT-60 connectors or Deans connectors all commonly used in the RC community.
DC2132A Power Supply problems  - Page 1
Forum section: electronics / beginners

author: FotatoPotato
author_rank: Regular Contributor
timestamp: December 14, 2018, 02:24:38 am
content: Hi all,So I just finished building my own version of the Analog Devices DC2132A bench power supply. All I really changed was the physical layout of the board to fit my needs, otherwise, there have been no changes to the schematic but I'm experiencing some issues.While both the voltage and current control work I am only able to go up to about 2.8v on the output of the linear regulators and the output of the DC-DC buck converter maxes out at 4.12v with a 31v input. I have looked around the schematic and probed the board to see if I could find anything that is wrong but I just can't seem to find anything wrong. I'll link both the reference schematic and my re-creation in Altium so that you guys can take a look and see if you can find something. If you guys have any questions on the design please let me know and if you find any faults, please let me know.Thanks!

author: perieanuo
author_rank: Frequent Contributor
timestamp: December 14, 2018, 07:14:52 am
content: hi,I don't get how you implemented dcdc with LTC3632(in his datasheet you input voltage to Vin pin, referenced to Gnd pin 8 and you 'take out' voltage after inductor connected on SW pin, also referenced to pin 8 ).In your shhematic you apply between Vin and some floating virtual GND and you output between that virtual gnd and the load GND.you made an -5V for some purpose?I don't see inductive load protection, Q1 may be the first to hit the bucketLet's come to the point, purpose of D5 is doing what?The tell us what voltage you have on LT3081/SET and Vout, when R31 is 0 with Ilim at max or disconnected and no load.regards

author: perieanuo
author_rank: Frequent Contributor
timestamp: December 14, 2018, 07:25:37 am
content: hi, on second verification, I think D5 has no place there, remove it an tell the result.

author: FotatoPotato
author_rank: Regular Contributor
timestamp: December 14, 2018, 08:24:16 pm
content: Hey perieanuo,Thanks for the reply! Unfortunately, I can't simply remove U5, It's needed to set the voltage on the v-limit potentiometer and it directly determined the output, however now I'm thinking that the problem lies in U5 and maybe it isn't supplying the correct voltage....I'll check and see if there is something wrong.Thanks!
DC2DC 1,5v to 2v - Page 1
Forum section: electronics / beginners

author: jarleiceman
author_rank: Contributor
timestamp: November 30, 2013, 06:32:51 pm
content: HelloI'm a man from the Cold North...Norway, and I have a question about DC2DC...:I shall use this in a set of active headphones..and there are a 1,5v AAA batery here, but the voltage is to low...I have too have at least 2v for it...(not more than 3,5v..)and the current is less than 100 mA, so I wonder if you have a solution for my project:with a small capasators diodes and resistor (at easy at is can be...) I dont want to use active compenents (like Op-Amps etc...)mabe a dobler of the voltage how do I do it....(I see I can use a DC.DC boost converter), but I want too make it cheap and with as less components as posible....senserlyjarleiceman

author: mariush
author_rank: Super Contributor
timestamp: November 30, 2013, 06:46:14 pm
content: It's not cheap, but it should work very well for your needs.I've recently done a project using LT1307:http://uk.farnell.com/linear-technology/lt1307cn8-pbf/ic-dc-dc-up-converter-1307-dip8/dp/9560394http://uk.farnell.com/linear-technology/lt1307bcs8-pbf/ic-dc-dc-up-converter-smd-soic8/dp/1273725It's available in DIP package so you can put it on a breadboard and you can basically follow the circuit in the datasheet and just adjust the two resistor to get the output to 2v or 2.5v or 3v or whatever you want. It's also available as SOIC or other surface mount stuff so you could use all surface mount stuff and do the dc-dc converter in about 2 centimeters of pcb...It can output up to 100mA, so it fits your needs.It's very efficient, it works with as little as 1v so it will even work with rechargeable AAA batteries and works at high frequency so you only need very small parts (an inductor, a diode, a few resistors and capacitors.. about 1-2$ worth of parts)Yes, I know you said you don't want active components... but at up to 100mA it's not quite as easy as you think to get good quality and performance.

author: jarleiceman
author_rank: Contributor
timestamp: November 30, 2013, 06:57:51 pm
content: Thank you mariush, i'l try this one..
DC/DC Buck converter drops voltage when connected to load. - Page 1
Forum section: electronics / beginners

author: Pariston
author_rank: Contributor
timestamp: October 03, 2020, 01:33:11 am
content: Hi,I've been trying to use MAXM15065 buck converter for my project, but I faced difficulties setting it up. At 39 Volt input voltage, I get 3.3 volt output as expected. However, once load is connected, I get significant voltage drop to around 1.2 volt. This buck converter was connected according to datasheet, and all tests performed isolated from the rest of the circuit. I will also attach link to datasheet and setup layout.https://datasheets.maximintegrated.com/en/ds/MAXM15065-MAXM15067.pdf

author: brucehoult
author_rank: Super Contributor
timestamp: October 03, 2020, 05:20:37 am
content: Presumably you're trying to pull more than 300 mA from it -- possibly much more but it's really hard to say as their output voltage vs current graphs don't go past the rated 300 mA and it might well drop off precipitously after that.

author: Pariston
author_rank: Contributor
timestamp: October 03, 2020, 05:35:31 am
content: I've tried connecting 220 ohm resistor as my load and ended up with 2.06 volt across it (9 mA)

author: tooki
author_rank: Super Contributor
timestamp: October 04, 2020, 05:54:37 pm
content: Could you post your circuit? (Schematic and a picture of it assembled.)
DCDC converter schematic review using TI LMR10510Y - Page 1
Forum section: electronics / beginners

author: aedancullen
author_rank: Newbie
timestamp: June 26, 2017, 05:31:08 pm
content: Hi, everyone.I'm designing a board for the Raspberry Pi Compute Module and I've drawn up a rough schematic of the power supply section. It uses two TI LMR10510Y ICs (datasheet:http://www.ti.com/lit/ds/symlink/lmr10510.pdf). The goal is to produce a 3.3V/1A output and a 1.8V/1A output from anything around ~4.5-5.5V input. The 3.3V rail needs to come up first.My schematic is attached.The question is: Are my voltage dividers on the FB pins drawn correctly for the output voltages I want? I'm specifically wondering about the 3.3V one. I understand the output voltage calculation on page 12 of the datasheet, but I was confused by the Design Example 3 given on page 17 - I'd think that the value of R2 should be 10K, not 100K, according to the information on page 12 for a 3.3V output. (R1 should be 4.5 times the value of R2, right?) In my schematic, I've followed the Design Example, but I don't know why R2 is 100K and not 10K like I'd expect.I'm probably missing something silly though. Any help is great; thanks

author: sdguy12
author_rank: Contributor
timestamp: June 26, 2017, 06:12:44 pm
content: It's a typo. The feedback connection is just a voltage divider. R1 should be 450k. If you want R1=45k, then R2 needs to be 10k.

author: aedancullen
author_rank: Newbie
timestamp: June 26, 2017, 06:15:34 pm
content: Thanks! That answers my question

author: sdguy12
author_rank: Contributor
timestamp: June 26, 2017, 06:19:06 pm
content: No problem. Datasheets are notorious for typos.....
DC/DC converter topology identification help - Page 1
Forum section: electronics / beginners

author: JimmyCad
author_rank: Newbie
timestamp: July 02, 2019, 02:36:31 pm
content: Hello,I have came across a DC/DC converter topology used in high voltage applications. However I am struggling to understand what is happening in the circuit. I will attach an image of the converter in question. It outlines that it is a full bridge/half bridge topology.I have seen both the half bridge and full bridge variants of the LCC converter, of which I am familiar with. However, the way this circuit is configured is quite confusing for me. I can only possibly think that the configuration is:Two parallel half bridge LCC converters, each feeding a primary winding of the transformer. The only reason I can see this being beneficial is because the HB converter typically presents the transformer input with half of the input voltage. maybe using two allows the full input voltage to be given, thus removing this drawback of the HB in comparison to the FB inverter which presents full voltage, which obviously is good for HV because the step up ratio is less in the FB variation. But I am fully confused by why it is labelled as a half-bridge/full-bridge converter - it can't be both, can it?I don't see any other reason to use a half-bridge converter in a high step up high voltaeg application.Thanks in advance!Jim

author: cur8xgo
author_rank: Regular Contributor
timestamp: July 02, 2019, 05:10:38 pm
content: Quote from: JimmyCad on July 02, 2019, 02:36:31 pmOkay it looks like there are two primary windings? If each one goes to its own half bridge, and they are wound opposite each other, doesn't that make the net effect a full bridge?

author: JimmyCad
author_rank: Newbie
timestamp: July 02, 2019, 09:07:17 pm
content: Okay it looks like there are two primary windings? If each one goes to its own half bridge, and they are wound opposite each other, doesn't that make the net effect a full bridge?That's what it looks like to me - but what is the point of using two half bridges, as opposed to a full bridge converter? What is the benefit of having two primary windings?Also, if the windings are wound opposite to each other - wouldn't that cancel the effects and result in zero net voltage applied to the transformer windings?