hybridfree/eevblog-posts huggingface dataset:
DC 5.5x2.1 jack with pin layout for (solder) breadboard or breakout board - Page 1
Forum section: electronics / beginners

author: Back2Volts
author_rank: Unknown
timestamp: November 04, 2016, 03:56:00 pm
content: Do they exist? Most of what I see out there has solder lug pins, and when not, no one seems to fit .1" grid.Combine that with a decent current rating...

author: Buriedcode
author_rank: Super Contributor
timestamp: November 04, 2016, 09:43:56 pm
content: Apparently this is compatible with 0.1" spacing:https://www.sparkfun.com/products/10811I checked the datasheet and it really doesn't look like it is. 5.8mm between outer connection and centre pin. Reviews seem to imply it does fit though.As for current rating, I wouldn't really trust these over a couple of amps.

author: Back2Volts
author_rank: Unknown
timestamp: November 05, 2016, 12:34:36 am
content: I had three of those;I think they came from Newark/e14.Just checked, I bought them from SparkfunThey seem to align into standard jumper breadboards, but the pins are bigger than what is supposed to go in them, so they will probably deform contacts permanently.A couple of days ago I placed one on piece of solder able breadboard, to build a breakout board power port for solder-less breadboard use. I bent the center and side pins to solder over the top surface and re drilled the hole for the bottom center one. The jack was secured properly, but it came out a bit messy.Today I built a second one because the first was too small for what I wanted to place on it. This time I re drilled all three holes. The problem with the drilling is that the tinned ring pads are mostly gone, so to hold the jack, I had to bend them under and bridge solder to the nearby pad. The pins are too short to reach to the pad, so again a bit messy.After both experiences, I think next time I will try to refine the first one, bending two pins over and drilling the bottom center.Thank your time looking into it. By the way, that datasheet says it will take 4A, which is not bad.

author: Monkeh
author_rank: Super Contributor
timestamp: November 05, 2016, 02:33:03 am
content: It may take 4A, but your breadboard will suck a lot at that.Make a simple breakout board for $JACK_OF_CHOICE, it'll cost pennies at OSHPark.

author: Back2Volts
author_rank: Unknown
timestamp: November 18, 2016, 11:36:11 am
content: Quote from: Buriedcode on November 04, 2016, 09:43:56 pmI figured out that for insertion of the bottom pin in solder-able breadboards, a little filing with a mini flat file will let it slip in.
DC alternator - ramp up the voltage? - Page 1
Forum section: electronics / beginners

author: THATguy
author_rank: Regular Contributor
timestamp: July 02, 2017, 12:20:35 am
content: I have an alternator with a charge regulator - came off a pedal-a-watt.Then I made a frame from bicycle bits, so I could have a portable generator.However the 125mm diameter cog only generates max 3vA bicycle wheel generates somewhere in the vicinity of 12 to 15v, the regulator limits this to 12v.As you can see from the picture I've been experimenting with making larger cogs - real pain to build.I've no information about the alternator, the pedal-a-watt company removed all the labels - I suspect it is from a scooter (moped).I saw this videohttps://youtu.be/wh8FbnZdhJg?t=469As you can see there are feedback wires to generate higher voltage.Could I do something similar, so I'm able to use the smaller cog and get my 12v output?
DC Analysis of NPN VDB Circuit - Page 1
Forum section: electronics / beginners

author: eev_carl
author_rank: Regular Contributor
timestamp: October 27, 2020, 02:27:20 pm
content: Hi,I built this circuit and modeled it in Multisim, but my calculations for a DC analysis don't match.I was expecting VBB = 10 * 4.7 / (4.7 * 10) = 3.2 V. VE = 3.2 - 0.7 = 2.5 V. IE = 2.5 / 220 = 11.4 mA. I get 2.30 V at the base though on both my real and simulated circuits.Is there something wrong with my selection of resistors? I tried same algorithm with other values and everything meshed.Thanks,Carl

author: ledtester
author_rank: Super Contributor
timestamp: October 27, 2020, 04:36:10 pm
content: QuoteYou probably mean 10V * 4.7kR / (4.7kR+10kR).You are not accounting for the base-emitter current.According to the Multisim analysis, the base current is 267uA. Note that 267uA*4.7k = 1.25V which is approximately the difference you're seeing.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 27, 2020, 04:51:34 pm
content: Notice what I_E * (R3) is.Tim

author: eev_carl
author_rank: Regular Contributor
timestamp: October 27, 2020, 06:53:49 pm
content: Thanks all.After reading the responses, I found a section in my textbook that said my simplified analysis was only good for *well-designed* circuits with the base current much less than the VDB current. In what I posted, they're the same order of magnitude (IB=281uA, IVDB=489uA).The VDB resistor values I wrote were working produced a much larger difference (IB=29uA, IVDB=797uA) for example.So, bad design on my first pass
DC+ and DC- needed - Page 1
Forum section: electronics / beginners

author: jeffjmr
author_rank: Regular Contributor
timestamp: November 09, 2021, 02:45:27 pm
content: I have one of those OPA541 signal generator amps. It works as advertised powering with my two channel Leader LPS-152. However this limits me to about 22v output with the Leader’s +/- 25v max supply and I need 30-40 output.I also have a B&K 1743, a single channel 35v unit. I can get up to 50v by combining the Leader’s two channels, and with the B&K I could theoretically get + and - 35v which would get me my 30v output from the amp.But the input to the amp has just three lines +, - and ground. I would have thought I could connect one PS to the + and ground, and with reversed leads the other to - and ground but that does not work. Is there a way to accomplish this with effectively two single channel power supplies?Thanks,Jeff

author: TimFox
author_rank: Super Contributor
timestamp: November 09, 2021, 02:52:53 pm
content: That connection should work: what did not work right when you did it? What voltages did you measure at "+" and "-" with respect to "ground"?

author: jeffjmr
author_rank: Regular Contributor
timestamp: November 09, 2021, 06:06:26 pm
content: I had 35 measured on the Leader and 35 on the B&K BEFORE connecting. I connected the Leader’s positive lead to the + and the Leader’s negative lead to ground. Still measured 35. Then connected the B&K positive lead to ground and negative lead to -.At that point I got my expected 35- but only 17.5 positive on the device. I suspect a current limiting issue but that shouldn’t have been an issue because I had not yet introduced a signal so was not asking for any output.Thanks.

author: TimFox
author_rank: Super Contributor
timestamp: November 09, 2021, 06:17:02 pm
content: How much current was being drawn from the positive supply at that point?

author: jeffjmr
author_rank: Regular Contributor
timestamp: November 09, 2021, 07:04:57 pm
content: I hadn’t taken note the first time but I just tried again and indeed the Leader was current limited. I missed the combined limitation of 1amp on the +/- 25v. I thought it could do 1amp each side.Thanks for your help. I am now confident that another B&K which can do 6 amps will get me where I need to be.Jeff
DC Bi-Directional Contactor failure in High Voltage Battery System - Page 1
Forum section: electronics / beginners

author: wjmuss10
author_rank: Newbie
timestamp: October 17, 2023, 11:12:10 am
content: I am having failures on a Bi-Directional DC Contactors used for High Voltage Battery systems for Energy storage.We use a Charge and Discharge contactor. 99% of the failure occurs on the charge contactor.Using a YM EVHB500-A-24 with a 24V Coil and built in economizer, Powered with a Meanwell WDR240-24 power supply through the BMS.Continually get adhesion faults where the charge contactor will engage but not stay latched. During initial installation this contactor opens and closes while the lithium cells balance.After teardown analysis, we found a mosfet on the economizer board is frying. This would occur if it sees 100V or more. Oddly, we can keep the contactor latched if we power it with a voltage higher than 24, around 48VDC but only after the initial failure.Question, shouldn't the built in economizer take care of the inductive voltages being generated when the magnetic field is closed? I understand diodes should be placed in parallel to the coil voltage but are they required when you have the economizer circuit?What else could cause a voltage spike into the economizer circuit?Thank you.
DC Bias for Loop Powered Devices - Page 1
Forum section: electronics / beginners

author: tarun172
author_rank: Regular Contributor
timestamp: February 03, 2017, 09:46:59 pm
content: This question relates to instrumentation and devices. Can a two wire HART Transmitter with analog 4-20mA be called as as Device requiring DC Bias? Hart Protocol link:https://en.wikipedia.org/wiki/Highway_Addressable_Remote_Transducer_Protocol.

author: danadak
author_rank: Super Contributor
timestamp: February 04, 2017, 01:48:35 pm
content: Not sure what you are asking.If device is passive than it needs power, typically loop will provide.If active device will supply loop power, again typically.https://en.wikipedia.org/wiki/Current_loopRegards, Dana.
DC bias on an LCR - Page 1
Forum section: electronics / beginners

author: Noody
author_rank: Contributor
timestamp: February 14, 2017, 04:10:47 pm
content: Hi,I have noticed a "DC bias" feature on some LCR units. What is it for and when could I need this?Many thanks.

author: tszaboo
author_rank: Super Contributor
timestamp: February 14, 2017, 04:49:10 pm
content: Ceramic capacitors (for example) have a high DC voltage dependence. They can drop their capacitance by up to some 70-90% at their rated voltage. Dave has a video on it, watch it.

author: rfeecs
author_rank: Frequent Contributor
timestamp: February 14, 2017, 05:39:40 pm
content: It can be used to measure voltage dependence of the capacitance of a diode. A varactor for example.

author: dacman
author_rank: Frequent Contributor
timestamp: February 14, 2017, 11:09:50 pm
content: The capacitance of a power supply filter could be checked at actual working voltage if within range.

author: Smokey
author_rank: Super Contributor
timestamp: February 15, 2017, 12:12:38 am
content: http://www.kemet.com/Lists/TechnicalArticles/Attachments/191/Why%2047%20uF%20capacitor%20drops%20to%2037%20uF-%2030%20uF-%20or%20lower.pdfDC Bias discussion starts at page 8... but the whole thing is seriously interesting.

author: Noody
author_rank: Contributor
timestamp: February 15, 2017, 11:19:11 am
content: Thanks guys! I'll watch Dave's video now and will study-up on the rest afterwards.It seems that the Applent AT2816 LCR that I was looking at getting, doesn't have a DC bias feature, yet some cheaper alternatives, do. I see why this is useful, so should I be considering the lack of DC biasing as a strong negative in getting the Applent? It's been 25 years since I last seriously played with electronics. I don't recall DC biasing being a feature back then.

author: tszaboo
author_rank: Super Contributor
timestamp: February 15, 2017, 12:05:23 pm
content: Depends what you are going to use it for. For inductors and resistors, it does not make a lot difference. For capacitors, you can just select ceramics which are known to behave well, or have datasheet with the information available. For a capacitor, it is a go/no-go test anyway.
DC blocking capacitors vs smoothing capacitors ? - Page 1
Forum section: electronics / beginners

author: komrad2236
author_rank: Contributor
timestamp: March 07, 2023, 07:43:43 pm
content: As my understanding goes, capacitors can block Direct Current, but also they can smooth out ripples in Direct Current ?(I am not even going to attempt to ask what is a term for these (decoupling,coupling,filter,bypass))What ?What is going on here and how do I tell the difference ?

author: TimFox
author_rank: Super Contributor
timestamp: March 07, 2023, 07:49:08 pm
content: Capacitors in series with a signalblockDC. (Coupling or DC block)Capacitors in parallel with a wire cansmoothDC. (Filter or bypass)(The latter means from the wire to ground or the other end of the power source.)

author: wraper
author_rank: Unknown
timestamp: March 07, 2023, 07:49:36 pm
content: All of them do exactly the same thing. Resist voltage change across them (pass AC) but do not pass DC current. All of those are simply applications but caps do exactly the same thing.
DC blocking capacitors - Page 1
Forum section: electronics / beginners

author: jgalak
author_rank: Regular Contributor
timestamp: April 18, 2018, 03:34:36 am
content: AC coupling of circuits is pretty common, with a simple series capacitor blocking the DC. What I've failed to find so far is any guidance on how to pick the right capacitor.Mostly I see thing like "just use a 0.1uF" or something.Is there any sort of formula or design method for determining the correct capacitor?ETA: not looking at a specific application, just a general understanding

author: hamster_nz
author_rank: Super Contributor
timestamp: April 18, 2018, 03:38:54 am
content: Yes, there is a formula. The blocking capacitor and input and output impedance form a high pass network, and can be analyzed as such.You need enough capacitance to pass the frequencies of interest, but not too much that it costs to much or that high frequency suffers.See things likehttps://www.electronics-tutorials.ws/filter/filter_3.htmlfor a full explanation.

author: jgalak
author_rank: Regular Contributor
timestamp: April 18, 2018, 05:44:23 pm
content: Ah! That may be what I was missing. I wasn't thinking in terms of filters, so didn't see where the R would come from.So if the blocking capacitor is in the middle of a 50 Ohm path, I just treat it as an RC filter with R=50 and pick the appropriate C? Or do I need to add the two 50 Ohm paths on either side and treat it as R=100 ?

author: ferdieCX
author_rank: Regular Contributor
timestamp: April 18, 2018, 07:21:05 pm
content: Yes, you have to add the internal resistance of the signal source at the input and the load resistance at the output.
DC boost converter 3.7v -> 5v, chip + battery very hot - Page 1
Forum section: electronics / beginners

author: Lycaon
author_rank: Contributor
timestamp: December 22, 2015, 04:11:35 pm
content: It's me again :pI've got a simple power "bank" set up which currently consists of one 18650 battery holding about 1300mAh, a boost converter, and a micro USB cord.I've got it all worked properly as far as I know (triple checked polarity all along the circuit with my DMM) and my phone is happy with the output, but both the battery and the converter get uncomfortably hot. It's not quite enough to leave a red mark, but it is enough that you can't hold it for too long.The chip on the converter is an MT3608 which I read over the datasheet for, but there was no info on temperature other than 155° C thermal protection cutoff.Is the heat from such a small voltage boost normal? I expect a lot of heat from higher voltage jump , but both the module and the battery are getting hot. I wanted to be sure I wasn't misusing it.

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: December 22, 2015, 05:18:04 pm
content: It sounds like your phone is charging at high amps and making the chip hot.

author: Lycaon
author_rank: Contributor
timestamp: December 23, 2015, 03:15:00 am
content: That's what I thought at first, but its doing this even with no load attached. I've checked for short circuits too. No luck.

author: Landrew2390
author_rank: Regular Contributor
timestamp: December 23, 2015, 07:38:39 am
content: I would start by measuring the actual current drawn by your phone. If it's drawing a large current load (~1000mA), you would see temperatures similar to what you're observing on the boost converter.I couldn't find a datasheet for a 1300mAh battery in the 18650 form factor. Most of the ones I'm seeing are rated much higher, but the consistent variable is do not discharge them at temperatures above 60 degrees Celsius. Changing to a larger capacity battery may help you stay under the maximum discharge temperature, but that's not a guarantee. As with all lithium batteries, try to keep it as cool and comfortable as possible.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: December 23, 2015, 09:53:42 am
content: Is it perhaps possible that the boost converter is making such short pulses that the current during those pulses is quite high? What kind of capacitance do you have between the pusling output and ground? if the values are high enough and the boost converter switches fast enough, the current spikes might be seeing a short even though there is none at DC.
DC boost convertor AND constant current supply? - Page 1
Forum section: electronics / beginners

author: eee
author_rank: Contributor
timestamp: November 12, 2013, 04:51:54 pm
content: Hi guys! I'm new here, just joined after seeing some amazing videos of Dave on youtube.I know quite a bit about DC boost IC chips, and constant current chips you can buy, but what about a combination of the two? Does such a chip exist that does 2 in 1?If not, will using a DC boost convertor, in series with a constant current chip work fine, or will there be issues such as impedance mismatch?

author: eee
author_rank: Contributor
timestamp: November 12, 2013, 06:22:48 pm
content: Thanks for your reply AcHmed99!The issue is that the supply voltage varies between 9.7V and 11.7, yet the LED requires at least 12.5V to be driven at the desired 1A. If I set this chip to operate at 1A, will it automatically boost the voltage to whatever the LED requires? (the hotter the LED gets, the less it's Vf is...)

author: gotvolts
author_rank: Contributor
timestamp: November 13, 2013, 03:29:22 pm
content: Correct, you won't be able to do the two simultaneously, but nothing will prevent you from using a voltage mode power controller as a current mode controller. You can use most any boost converter IC that is advertised as voltage mode, and simply configure it to regulate output current. This is commonly done for LED circuits. Current is regulated and the output voltage is clamped by the Vfwd of the LEDs.

author: codeboy2k
author_rank: Super Contributor
timestamp: November 13, 2013, 08:33:29 pm
content: And just to make the idea complete in the thread... I drew up a simplified schematic to show how to use a basic buck voltage regulator as a current regulator with a LED string.As a voltage regulator, you would set a top and bottom feedback resistor to divide the desired output voltage down to the feedback voltage. Then the current limiting resistor RLIMwould limit the current through the LED string.As a current regulator, the feedback voltage is now developed across RSET, so choose RSET= VFB/ISET. The controller will now adjust the voltage output to whatever value it needs to be at to maintain ISETacross RSET
DC Boost regulator MC34063 circuit - Page 1
Forum section: electronics / beginners

author: rj88
author_rank: Contributor
timestamp: August 20, 2014, 05:58:53 am
content: Hi, I'm hoping someone might be able to help me.I am trying to simulate a circuit involving the MC34063 that's illustrated in the datasheet (attached as JPG) using LTSpice. It's a simple 12V -> 28V DC-DC converter.I downloaded the model (attached) for the MC34063 so that I could use it in LTSpice. It seems to be ok when I tell it where the files for the model are (C:\DATA)Have also attached the LTSpice model.The problem is that I don't get 28V at the output - I get around 11V! I'm very new to this so have probably done something silly. I'm also not sure what values the input and output capacitors should be.Any help is very much appreciated.Thanks

author: eetech00
author_rank: Regular Contributor
timestamp: August 21, 2014, 03:41:25 am
content: HiTry this one.eT

author: rj88
author_rank: Contributor
timestamp: August 21, 2014, 06:23:00 am
content: Thanks so much eetech00, I think you helped me on the other forum too!All working now
DC booster 5V to 15V 200mA - Page 1
Forum section: electronics / beginners

author: Back2Volts
author_rank: Unknown
timestamp: September 21, 2022, 03:42:07 pm
content: I need a booster for a project I am working on. Are there any commercially available, other than Chinese on eBay?

author: langwadt
author_rank: Super Contributor
timestamp: September 21, 2022, 03:54:32 pm
content: plenty, likehttps://www.digikey.dk/en/products/detail/gaptec-electronic/3S7A-0515S1U/13692274

author: Back2Volts
author_rank: Unknown
timestamp: September 21, 2022, 05:55:10 pm
content: Thank you. I was searching on DIGIKEY US this morning, but I missed it.I do not need the isolation, but I assume I can connect both grounds

author: Terry Bites
author_rank: Super Contributor
timestamp: September 21, 2022, 06:36:28 pm
content: "Boost Converters" abound on ebay. USB to 15V boost is easy to find.

author: rooppoorali
author_rank: Regular Contributor
timestamp: September 22, 2022, 04:52:59 am
content: This one can provide up to 4A:https://artofcircuits.com/product/xl6009-step-boost-regulator-module-4-0a-output-currentYou can adjust the output voltage from 5-39V.
DC current and Oxidation Question  - Page 1
Forum section: electronics / beginners

author: teslatek
author_rank: Newbie
timestamp: January 05, 2018, 06:58:23 pm
content: Hey everyone i'm new to the technical side of the electronics world, i watched Daves tear down of that electronic rust protection scam unit and i was wondering, if the vehicles chassis was not used as dc ground , like if each wire that uses the negative chassis ground was cut and rewired to a junction that connected to battery's negative terminal instead of grounding to the frame would that potentially lower the amount of rust that would accumulate over time , i know it wouldn't be cost effective to do this but would it work? , i set up a nice lab and machine shop a year or so ago so i have all the gear to run tests and custom build whatever i need , any help would be greatly appreciated , thanks

author: Zero999
author_rank: Super Contributor
timestamp: January 06, 2018, 01:16:08 pm
content: Quote from: teslatek on January 05, 2018, 06:58:23 pmYes, I believe not using the vehicle chassis as a current carrying conductor would cut down on corrosion. Using the chassis for return current is prohibited in military vehicles, but that could be to comply with the stringent EMI standards, more than reducing corrosion.Irrespective of the above, it's still a good idea to connect the negative terminal to chassis, because it stops the electrical system from floating at potentially high voltages.
DC current reading stabilization  - Page 1
Forum section: electronics / beginners

author: Grey_Beard
author_rank: Newbie
timestamp: September 03, 2025, 05:24:27 pm
content: I am repairing an old style auto battery charger (transformer, diode rectifier).The current meter was pooched so I replaced it with a cheap digital one.(https://www.digikey.ca/en/products/detail/dfrobot/DFR0245-G/6588434).Once installed, the first problem was that the display flashed.I guessed that the cause was the varying supply voltage and was able to fix it by tapping off the rectifier output with a diode and then putting a filtering cap across the power input to the meter.So far so good.However, when the charger is in operation, the reading continually varies, typically within a range of a few amps.While I can get a general indication of current flow based on the range of fluctuation, it would be nice to get a stable reading.I thought of trying to isolate the reading with a diode and using a cap to average out the reading, but that won't work because even at maximum current flow, the voltage drop across the shunt is only 0.009V.A cap across the output won't work because it would need to be nearly as big as the charger itself to be effective, not to mention costing a fortune.I realize that an analog meter wouldn't have this problem, but I couldn't find one at an affordable price.Now I am open to suggestions.Thanks in advance.

author: TimFox
author_rank: Super Contributor
timestamp: September 03, 2025, 05:33:47 pm
content: Have you tried a simple low-pass filter with a series resistor (not diode) from the shunt and a parallel capacitor across the meter input? The battery charger current, with no filter capacitor, will have large ripple at line frequency or twice frequency, which will “beat” with the sampling rate of the digital voltmeter.The resistor should be 1% or less of the (high) input resistance of the meter, and the capacitor should give a time constant long compared with 1/60 or 1/50 second.

author: BeBuLamar
author_rank: Super Contributor
timestamp: September 03, 2025, 06:57:11 pm
content: I don't know if it would correct your problem but try power the the meter with a separate power source (battery if you have to). If it works then I guess we can figure something out. The data sheet said to use isolation power supply for the meter.

author: Grey_Beard
author_rank: Newbie
timestamp: September 03, 2025, 11:42:57 pm
content: To TimFoxThe low pass filter idea is interesting.I'll try it the next I order parts.To BeBu LamarI already have steady power to the meter.Thanks to both of you for your help.

author: BeBuLamar
author_rank: Super Contributor
timestamp: September 04, 2025, 11:49:05 am
content: Quote from: Grey_Beard on September 03, 2025, 11:42:57 pmI don't mean steady power. I mean power isolated from the charger that is what the data sheet recommended.
Dc current smoothing?  - Page 1
Forum section: electronics / beginners

author: Sounduser
author_rank: Contributor
timestamp: February 07, 2016, 02:45:26 pm
content: My dc pumps turn on and off to create random flow and waves.This causes the power supply fan to go on and off with the pumps. Due to current being drawn 50% of the time.How can I calculate the value of a capacitor to even out the current draw?The pumps draw around 1 amp at 24 volts.I'd like to add a cap or two to each pump to smooth the draw to a constant 500ma.With minimal ripple.Thanks for you help.Google just gives calculators for Ac supplys.

author: Chalcogenide
author_rank: Regular Contributor
timestamp: February 07, 2016, 02:52:56 pm
content: Capacitors can only smooth out relatively fast transients; you would be better off removing the original fan and installing a quieter one, maybe always running at a lower rpm (1/2 or so). Or, use a bigger power supply that can run fanless at a 1A load.

author: Sounduser
author_rank: Contributor
timestamp: February 07, 2016, 04:42:34 pm
content: Is once or twice a second too slow?

author: Chalcogenide
author_rank: Regular Contributor
timestamp: February 07, 2016, 05:39:39 pm
content: To have an effective smoothing at <1Hz you would an irrealistic LC filter at 0.1Hz or so. With a 1 Farad capacitor and a 1 Henry inductor, assuming a 24 Ohm load (1A at 24V) you would get roughly 0.16Hz cutoff frequency, and it still still wouldn't completely smooth out the current draw (and both values of the filtering elements are absolutely huge and unrealistic, not to mention incredibly expensive if you could even find them).

author: Marco
author_rank: Super Contributor
timestamp: February 07, 2016, 07:14:58 pm
content: A 24V/2A power brick is ~10$ delivered ...

author: Sounduser
author_rank: Contributor
timestamp: February 07, 2016, 08:17:01 pm
content: I've replaced 5 wall warts with a 24 volt psu.No worries if it's impractical. It's not a big problem. I was hoping a 10000 mike cap would even out the draw.No problems.
dc-dc boost convetter cascade (series) - Page 1
Forum section: electronics / beginners

author: tural_h
author_rank: Newbie
timestamp: November 14, 2024, 05:57:02 pm
content: hello everyone, i made a cascade dc dc converter using mc34063 but using an external transistor, my main goal is to charge the capacitor at the 2200uf output in about 5-8 seconds, the input voltage is 3.7 ideally when the voltage is 6-7V for this I used two step up circuits first increased to 10V and then I need to get 80V but when I connect the second dc converter, the voltage at the output where it should be 10V drops to 3, the problem is how can I organize a cascade amplification circuit and what could be my problem? thanks for helping

author: Andy Chee
author_rank: Super Contributor
timestamp: November 14, 2024, 07:15:32 pm
content: The source pin of the MOSFET should be connected to GND.

author: PGPG
author_rank: Frequent Contributor
timestamp: November 14, 2024, 09:04:47 pm
content: I have Motorola Databook (Linear and Interface Integrated Circuits) from 1987 and MC34063 is there. But I'm sure that several years earlier I had xero of μA78S40 (=MC34063+OpAmp). It was first DCDC IC I have read about.20+ years ago someone specializing in DCDC told me that this IC is so old and so bad that it is waste of time to try to use it.Just have it in mind.

author: tural_h
author_rank: Newbie
timestamp: November 14, 2024, 09:58:04 pm
content: hello, yes you are right, it works with a frequency of 100 kHz maximum and uses a Darlington pair, which is an additional loss and slow switching, I will have to look for another option

author: PGPG
author_rank: Frequent Contributor
timestamp: November 15, 2024, 12:31:50 am
content: I'm not sure, but bigger problem than these mentioned by you is its IC control scheme not ensuring even close to stable frequency.In my opinion good ICs are those with current mode control loop (easier to stabilize than voltage mode as have one pole less in feedback loop).I use only step-down ICs and I like the best COT (Constant On Time) control (see LM5017) as it reacts to load change in one pulse (while current mode needs 5..10 pulses to notice that load has changed).
DC-DC BST900 Boost Converter Need help to repair  - Page 1
Forum section: electronics / beginners

author: MasterCATZ
author_rank: Newbie
timestamp: November 19, 2018, 04:30:23 am
content: I used my DC BST900w Boost Converter to charge my e-bike , we had a storm this weekend that blew my bike away while the charger was still plugged in and pulled the charger into some waternow I thought I had dried it all but forgotten to empty out the water out of the socket of the controllers breadboard , so when I started it up the voltage kept creeping up until it hit max voltage and something zapped , I can not see any damage however , but it no longer outputs boosted voltage if I have 24v input it will not output 53v but will output only 24v @ 0 amps and has VO and CC LED lit , if I have 48v input ( 52 ish volts) it will just pass that through and show the current draw but will not limit the current or limit the output voltage , ideally all I need is a current limiter to get me out of trouble I keep the 13s lithium cells @ 53.3V and want to charge them @ 1a ( 4a Max )any idea where I should start looking , if trying to boost from 24v to 48v ( 53.3v ) the constant Voltage LED lights up then goes immediately offthe circuit can still detect the voltage on the output sidethese are cheap but I need a solution for charging my bike while I wait for a replacementhttps://www.banggood.com/B900W-NC-DC-Constant-Current-Power-Supply-Boost-Module-Ammeter-p-1059239.html?cur_warehouse=CN
DC - DC converter module, buck - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: April 26, 2016, 07:23:08 am
content: I need three dc-dc modules which cah below specs:1. Input: 12V-16.8V2. Out1: 12V/5A3. Out2: 12V/3A4. Out3: 5V/2AI had looked into net & found that below dc-dc are ok:http://www.digikey.com/product-search/en?keywords=%20UWE-12%2F6-Q12PB-Chttp://www.digikey.com/product-search/en?keywords=UWE-12%2F6-Q12PB-C1. Problem I see, they are isolated. Can I short its Vin- & Vout-, & will it still work?2. Do these dc-dc require external heat sinks, or provided system is at room temperature they will work?In datasheet they have placed additoanl AL baseplate

author: Psi
author_rank: Super Contributor
timestamp: April 26, 2016, 07:45:38 am
content: Quote from: Vindhyachal.takniki on April 26, 2016, 07:23:08 am1. Yes, you can short one of the outputs to one of the inputs on an isolated module to create a positive or negative supply reference to input gnd or Vin2. Not normally, they are a module, you use use as is. It will have a max ambient operating temp though. So you will have to be under that. Looks like with that module you can buy the module with or without the base plate. If you get the base plate version the max op temp increases from 85C to 100C

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: April 27, 2016, 04:05:19 pm
content: thanks
DC-DC converter module - High quality? - Page 1
Forum section: electronics / beginners

author: Tantalum
author_rank: Regular Contributor
timestamp: April 24, 2019, 05:47:24 am
content: HelloI needed a DC-DC low ripple 3-5A converter module, but with quality components (caps, inductors,...).Where could I find some with decent quality?ebay/aliexpress is crowded with Chinese modules but I don't trust the specs announced.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 24, 2019, 12:57:32 pm
content: Vicor is a good brand, very compact also -- but you'll pay for it.I forget if they make anything that small actually. There are plenty of other major brands, in any case.I don't know offhand any that are specifically low ripple. You are expected to add filtering yourself, as need. (Many don't even have the required bypass capacitors onboard!)Tim

author: palpurul
author_rank: Regular Contributor
timestamp: April 24, 2019, 01:24:48 pm
content: There are many inDigikey. I am sure you can find many that suits your application. You can get them in very easy to use DIP packages too.

author: MadScientist
author_rank: Frequent Contributor
timestamp: April 24, 2019, 11:11:50 pm
content: Check out tdk-lambda , I regard them as the rolls Royce of dc dc converters
DC-DC converter operational test - Page 1
Forum section: electronics / beginners

author: spetroce
author_rank: Newbie
timestamp: December 11, 2015, 05:26:39 pm
content: Hello everyone, my first post, but I've been a watching EEVBlog since the beginning. I scored about 10 brand new DC to DC converters at an internship I did a couple years back for a military robotics company. Manufactured by Vicor and model number VI-223-IW-B1. I attached the PDF for the unit. They are 36V input at 135W max and 24V output at 100W max. I've never used a DC to DC converter before, let alone one of this size or cost. I have no test schematic so I am not sure how to properly operate this unit. What I am confused about are the gate and sense connections. The sense I think I can just ignore. The gate though is strange to me. I don't understand why it would be necessary to have a gate on a DC to DC converter. Can anyone please shed some light on this or perhaps share a few words on how to properly connect these on the bench? I just want to test them all so I call sell them on eBay. Thanks.

author: spetroce
author_rank: Newbie
timestamp: December 11, 2015, 08:18:34 pm
content: That's perfect. Thank you very much.
DC-DC converter or application for microtransformer with galvanic isolation - Page 1
Forum section: electronics / beginners

author: miguelrdz
author_rank: Newbie
timestamp: May 29, 2018, 02:24:40 pm
content: Hi guys! I'm working in my thesis and I need to demonstrate the application for an (galvanic) insulated air core microtransformer with high coupling factor (k). My first thought was to build a digital isolator but I don't really see the advantage of the high coupling compared to the usual devices which use medium k transformer. Some people pointed out that DC-DC converter could be a good idea but I'm not very familiarized with them.I did some research and I see that forward converter or flyback are the best options for the design (right?)Which one would you consider? Can you think in any other approach?The limitation that I see is that I'm working with an air-core transformer which is probably not ideal. Also since it is a microtransformer, the whole circuit should be as small as possible to take advange of the size feature (not CMOS design though)Thanks in advance!

author: David Hess
author_rank: Super Contributor
timestamp: May 29, 2018, 04:32:48 pm
content: Forget using a forward or flyback converter and instead use an inverter. An air core transformer will have a very low inductance compared to its high self resonate frequency and no energy storage so think of it more as an RF transformer and drive it with the lowest feasible RF frequency as part of an inverter.

author: miguelrdz
author_rank: Newbie
timestamp: May 29, 2018, 07:41:05 pm
content: Thank you! As you can see I’m pretty lost in that regard. I’ll do some research in RF transformers, if you know any helpful source/book please let me know.Thanks again

author: David Hess
author_rank: Super Contributor
timestamp: May 29, 2018, 11:19:54 pm
content: Probably the thing to do or at least what I would try is to add a resonating capacitor to the primary side and drive it like a resonate circuit. This is how most of the various wireless (inductive) charging standards work. The advantage of resonance is that the impedance seen by the amplifier is much higher and easier to deal with.Inverters which use transformers that have a core do not usually bother doing this because the high inductance of the transformer makes it unnecessary. One exception however is theresonant Royer inverterwhich is often used todrive fluorescent lamps.
DC-DC isolated Zeta converter - Page 1
Forum section: electronics / beginners

author: GuilTy
author_rank: Contributor
timestamp: December 19, 2015, 12:51:54 pm
content: Hello everybody,I want to construct a DC-DC isolated zeta converter with the following specificationInput voltage:-min 8V-max 14VOutput voltage:-constant 5VOutput power:-min 5W-max 12WThe ripple current throug the inductances(L2 and Lm) are set to 1/4*current throug them, the ripple through the first capacitor(C1) is chosen at 1/10*voltage through it, and the ripple through the output capacitor(C2) is set at 100mVpp.Case 1:-input voltage Vg=8V and output power P=5W-in this case the load(R1) is 5ohm, the duty cycle is 0.55, and the n parameter for the transformer is n=0.5. The M parameter for the converter is M=Vo/V1=0.625.-the output voltage is fixed around 4.2V, instead of 5V and I believe that the ripple from the output is too high.The other cases are:-V1=14V, P=5W-V1=8V, P=12W-V1=14V, P=12WI don't understant why the output voltage is fixed around 4.2V, and why the ripple is so high. The components in the other cases are different from this one and they depend on the input voltage and on the output power. Maybe I don't know how to read the results of the simulation or they are wrong.I've attached a few prinscreens with the schematic, output voltage and with the litteral expression of the currents through the inductances and with the voltages through capacitors.Im=current through the magnetizing inductandeIl2=current through the second inductanceVc1 and Vc1 are the voltages through the capacitorsPS: this is the ideal case of the convertor.Thank you,GuilTy

author: bugs
author_rank: Contributor
timestamp: December 19, 2015, 03:08:07 pm
content: Did you take the voltage drop over the diode into account?

author: GuilTy
author_rank: Contributor
timestamp: December 19, 2015, 03:59:05 pm
content: I didn't take it into consideration because in the ideal case the diode is considered as a short.

author: Kalvin
author_rank: Super Contributor
timestamp: December 19, 2015, 04:39:57 pm
content: Quote from: GuilTy on December 19, 2015, 03:59:05 pmCheck the manual and you may notice that the diode threshold voltage is 0.6V by default. Check also other components' model default parameters, and you may find the remaining missing voltage.

author: GuilTy
author_rank: Contributor
timestamp: December 19, 2015, 09:35:52 pm
content: Quote from: Kalvin on December 19, 2015, 04:39:57 pmThank you @Kalvin, I did what you said and the output voltage is around 4.8V~4.9V.

author: GuilTy
author_rank: Contributor
timestamp: December 19, 2015, 10:12:50 pm
content: I have another question. Why does this appear during the transient regime? I've put it into a red square.
DC-DC Step-down converter in series to work as symmetrical PS? - Page 1
Forum section: electronics / beginners

author: dougduck
author_rank: Newbie
timestamp: May 31, 2024, 06:35:02 pm
content: Hi,I have 2 DC-DC Step Down converters, with isolated input (are powered by different transformers).What are the problems and precautions that need to be used in series to make a symmetrical PS?Attached is the simplified schematic of what I thought of doing, placing a BJT transistor mainly to determine what will now be NEGATIVE... and this also helps a little with the noise as a result.What worries me is that the DC-DC modules switch the positive (obviously)... if one rail drains more current than the other, the circuit could become unbalanced/oscillating and compromised?Regards.

author: xvr
author_rank: Frequent Contributor
timestamp: May 31, 2024, 07:09:41 pm
content: If output from transformers arefully isolated(including rectifiers after them) than you can use DC/DC on positive wire (for each transformer) and connect their (DC/DC) output in series.No any precautions required.

author: thm_w
author_rank: Super Contributor
timestamp: May 31, 2024, 11:09:32 pm
content: You can also get modules that will give you +/- supplies, if you have a single transformer.Or just a single negative supply.https://www.aliexpress.us/item/3256805319354581.htmlhttps://www.aliexpress.us/item/3256804077079520.htmletc

author: ArdWar
author_rank: Frequent Contributor
timestamp: June 01, 2024, 12:29:32 am
content: Quote from: xvr on May 31, 2024, 07:09:41 pmPast certain power (and for certain design in general) at least put diodes parallel with the outputs. It protect the converter when one of them is unpowered.

author: dougduck
author_rank: Newbie
timestamp: June 01, 2024, 11:50:13 pm
content: Quote from: ArdWar on June 01, 2024, 12:29:32 amschottky or anyone that supports max voltage?

author: Konkedout
author_rank: Frequent Contributor
timestamp: June 02, 2024, 02:21:05 am
content: The diodes are connected antiparallel with the outputs, to clamp reversal of the output.I did not notice what is your output voltage. Lower Vf offers more protection but the diode reverse capability has to be adequate for the voltage involved.
DC-DC variable voltage and current lab power supply  - Page 1
Forum section: electronics / beginners

author: bengaltiger
author_rank: Newbie
timestamp: August 07, 2012, 02:54:39 pm
content: Hi,looking for simple DC-DC variable voltage and current lab power supply circuit.Input power supply 12 volts , 2 amps.output variable voltage (3 to 12 volts) and variable current. (current limiting with LED indicator)Also I will add digital voltmeter and ammeter module.Regards,BT
DC-DC - Page 1
Forum section: electronics / beginners

author: onis_uk
author_rank: Contributor
timestamp: March 22, 2017, 11:53:40 am
content: If I were to power an amplifier with a laptop smps brick is there a nice way to step down the voltage from 19v dc to 12v dc?There are plenty of crusty ebay buck converters out there but i need about 50W capacity.

author: Ian.M
author_rank: Super Contributor
timestamp: March 22, 2017, 12:01:08 pm
content: No, 50W out is 4.17A which would be really pushing it for an EBAY buck converter made of pure 'Chinesium' + there is a high probability that at light loads either it or the laptop PSU will go into discontinuous mode and produce a lot of AF ripple, and at higher outputs, the PSU and the buck converter may 'beat' with a difference frequency in the AF range.If you need 12V at over a fraction of an Amp, for audio of any better quality than a 'Tannoy' style PA system, don't start from a laptop power brick!

author: sleemanj
author_rank: Super Contributor
timestamp: March 22, 2017, 12:32:46 pm
content: Ones like this cc buck are commonly sold as 150w at usual places, of course thatis fantasy at least without fan, but I have pulled 40w out at 10v from 48w@32v input, my notes say continuous but I don't recall how long that was for exactly, but temperature rise was 32'cI did not look at ripple

author: ElectronicCat
author_rank: Regular Contributor
timestamp: March 22, 2017, 01:59:03 pm
content: Does it need to be powered by a laptop charger? You'd probably be better off just buying a 12v 50W power supply or re-purposing a desktop power supply. If you do need it to be powered by the laptop charger, you might be able to get away with a beefy linear regulator which would be the simplest solution, but that's assuming the laptop supply can deliver ~80W and you'd also need a heatsink capable of dissipating ~30W. Not ideal and not very efficient either. I wouldn't trust any eBay-grade buck/boost converters but you could either look into designing one yourself or buy a module from a reputable distributor.

author: dimkasta
author_rank: Regular Contributor
timestamp: March 22, 2017, 02:42:25 pm
content: Be sure to check any inrush currents on those things.A big inrush could trigger the charger's overcurrent protection.
DC driver for piezo disc actuator - Page 1
Forum section: electronics / beginners

author: ganzuul
author_rank: Contributor
timestamp: August 03, 2014, 12:10:42 am
content: Hello! I'm looking for feedback. =)This is supposed to be a high-voltage DC driver for a piezo disc sounder turned actuator. It's my first ever electronic circuit design. I'm sure there are entire fields of knowledge missing from it... It is very much a work in progress but it is probably time I showed my work to somebody.A piezo disc should not tolerate more than 180V input, but at DC levels their impedance is very high, and since they can also return knocks as high voltage into the circuit I've chosen to base this amplifier on TV horizontal deflection output transistors, NPN BJTs with a Vmax of 1500V or more.The power supply I'm looking at right now is a CCFL driver from a laptop, Royer oscillator, which gives out 1000V square wave at 50kHz, which I intend to rectify to ±1000VDC. I have not yet started looking into how I might obtain less voltage from these things. All driver boards I have looked at as of yet are controlled by a 5001C PWM generator, so I can get at the pins if needed. I'd prefer to make this part of the circuit modular and uninteresting, so that others who emulate it need not fiddle with it. I hope to simply limit current to 5mA as early as I can in the HV side, and this current limit is very important to the environment the circuit is intended for.REDACTEDIn my breadboard test of this circuit, it really does appear to work as an amplifier. The author seems to refer to it as a push-pull Class A. I think it is just elegant in its simplicity and believe that for my HV, mA application thermal dissipation should be a non-issue. Can you confirm?-http://sound.westhost.com/jll_hood.htmI hope to obtain 16 bits of dynamic range out of this thing, and probably on a logarithmic scale, actuator position to voltage. The piezo disks I have to test with are the cheapest pre-soldered ones I could find on Aliexpress, and for their quality I don't mind testing them to destruction at all. I intend to operate six of these actuators total, 3 in parallel, to position two mirrors for a laser. If successful these designs will become open hardware and licensed according to the art.ED:The actuators probably don't need such a huge stroke, so a DIY op-amp will suffice. The circuit I theorized about in this thread won't be developed into anything functional. I'll be looking at components like the ones referenced here instead, if I actually need a really high-voltage op-amp:http://www.repairfaq.org/sam/laserhpd.htm#hpdmpd3
DC dummy load - Page 1
Forum section: electronics / beginners

author: Samwel
author_rank: Newbie
timestamp: June 20, 2016, 08:43:09 pm
content: Hi, can anyone share with me a dc load circuit which has an lcd and is adjustable ? This circuit has to use an lm358.Thanks.

author: Signal32
author_rank: Frequent Contributor
timestamp: June 20, 2016, 09:13:16 pm
content: http://dangerousprototypes.com/forum/viewtopic.php?f=19&t=3532Looks like no firmware though