hybridfree/eevblog-posts huggingface dataset:
is this a good deal - Page 1
Forum section: electronics / projects

author: odell
author_rank: Contributor
timestamp: March 23, 2012, 04:46:58 am
content: is this a good dealQTY 100:BARRIER TERMINAL BLOCK 5 POS VERTICAL H272 $3.99 FOR ALL

author: Unknown
author_rank: Unknown
timestamp: March 23, 2012, 06:43:47 am
content: Quote from: odell on March 23, 2012, 04:46:58 amIf you need 100 or so 5 way terminals it is. Check the postage before clicking buy.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 23, 2012, 07:12:51 am
content: Mount them in a line & you have a 500 way terminal block!

author: kripton2035
author_rank: Super Contributor
timestamp: March 23, 2012, 07:45:05 am
content: good deal if you need them...otherwise ?but dont forget you need also the female part of the connector !

author: Psi
author_rank: Super Contributor
timestamp: March 23, 2012, 11:57:18 am
content: Yeah, it's not a good idea to buy things JUST because they're a good deal. It leads to massive stocks of junk lying around.Actually, nevermind, junk lying around is part of the hobby

author: Polossatik
author_rank: Frequent Contributor
timestamp: March 24, 2012, 07:01:33 pm
content: Quote from: Psi on March 23, 2012, 11:57:18 amthis board needs some kind of like button

author: tekfan
author_rank: Frequent Contributor
timestamp: March 24, 2012, 09:50:48 pm
content: Quote from: Polossatik on March 24, 2012, 07:01:33 pmThe problem is that most people on this forum would also like a dislike button under the like button.I think it's unnecessary to rate topics. It might be interesting to one person and not to the other.BTW I think there is a star thing ontop of each thread for ratings.But yes. The inevitabile stockpiling of unneeded components is almost an essential part of electronics.I often buy things that are really cheap because I think they might come handy some day. Most of the time I am wrong.And when I do need a certain component I never seem to find the right one.Then comes the thinking similar to this:The schematic says I need a 12K potentiometer but I can't find one. What's the closest thing I've got? 10K? No, I just used up all of those.What about 20K? No, I don't seem have those either. Hey, A 22K potentiometer! Now we're talkin'! Solder it in and off we go!Then you end up with a working circuit with half the values very different. Looks like this is mandatory when making prototypes.
Is this a good enough Input stage for industrial use case? - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: December 22, 2019, 10:15:47 am
content: Hi,I want to apply an isolated 220V AC mains to a system, is this input protection enough? Note: I have to use the least amount of components in here, Since the design needs very Small PCB area!

author: David Hess
author_rank: Super Contributor
timestamp: December 22, 2019, 05:05:57 pm
content: Even if the 220 volt AC source was isolated, I would want galvanic isolation unless the 220 volt AC source was an isolated winding on a transformer which only went to the measurement input. If I wanted to just measure presence of the 220 volts AC, then an optocoupler would be a good choice for isolation.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: December 22, 2019, 05:13:02 pm
content: 1. Is D1 a bridge rectifier? That doesn't provide isolation.2. What are the power and voltage ratings of R1, R6?3. What are the voltage ratings of R2, R3?4. Do you have enough space for creepage and clearance?5. What happens if D3 fails?

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: December 23, 2019, 06:49:29 am
content: It's for measuring the AC, and the input is a winding on an isolated transformer,All resistors are 0805 and they have a 150V working voltage and D1 is 1000V bridge rectifier
Is this a good idea to tackle the minimum load requirement of my SMPS design? - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: May 03, 2016, 06:16:59 pm
content: Another question about M103v2 project's auxiliary rail. All SMPS have a minimum load requirement (e.g. 10%) but I really don't want to burn away this current on a resistor (something I probably have to do on the main output strips, but maybe not on the auxiliary rails)The auxiliary rail have a maximum rated output of 3A at 5.3V. Since I have an LCD screen, a Bluetooth module (behind a linear regulator) and a microcontroller running off the auxiliary rail, is it a good idea to keep the rail loaded by forcing all three components operate at maximum power at all time? This means forcing the Bluetooth module to keep broadcasting beacon signal at maximum power, avoid using any sleep mode on the MCU, and keep the backlight of the LCD at maximum brightness at all time. Or should I just add a resistor to burn away the power, just like the main output strips?

author: Siwastaja
author_rank: Super Contributor
timestamp: May 03, 2016, 06:37:32 pm
content: Quote from: technix on May 03, 2016, 06:16:59 pmNot at all, this is a misconception!In fact, most SMPS designs do not have any minimum load requirement whatsoever. Efficiency is of course poor at low loads. Most modern controllers implement pulse-skipping modes to improve efficiency at the cost of increased ripple voltage at low loads."M103v2" doesn't say anything to me, but minimum load is only necessary on some designs with multiple outputs from a single transformer, like a PC power supply. Unless this is your case, you should fix the design to get rid of this ridiculous minimum load requirement.

author: technix
author_rank: Super Contributor
timestamp: May 03, 2016, 08:16:06 pm
content: Quote from: Siwastaja on May 03, 2016, 06:37:32 pmI am kind of forced into using the forward topology as all my output rails can vary very wildly. The primary output strips are full-blown adjustable CC/CV lab bench supplies, so crazy voltage changes are given. The secondary +5.3V rail is powering all internal logic while also allowing an external device to draw up to 2.5 amps from its USB tablet charging port (as it is controlled over Bluetooth, this is a convenient addition)Forward converter have a minimum load requirement. That is what I am trying to deal with here. I calculated the circuit to require a minimum output current of 100-150mA, which is about the current draw of a single LED. So I just keep one LED shining when the corresponding channel is operating (status LEDs for primary output strips, the backlight of the LCD display for the secondary channel)
is this a mosfet,jfet or simple transistor - Page 1
Forum section: electronics / projects

author: haseeb zaib
author_rank: Contributor
timestamp: November 03, 2021, 10:48:53 am
content: Hi, Can anyone from this xray image of this component tell me is this a to92 mosfet,jfet or transistor being used ?

author: daqq
author_rank: Super Contributor
timestamp: November 03, 2021, 11:34:56 am
content: If the white stuff is conductive copper then it's a two wire device. So diode, zener, shunt reference or something along those lines. That said, even for an xray, the image quality is atrocious.

author: magic
author_rank: Super Contributor
timestamp: November 03, 2021, 05:03:53 pm
content: Two pins out of three are connected with hair-thin bond wires, you probably wouldn't see them here.If anything, there is too much stuff in there which I can't quite figure out what it is.That being said, the only information you could get from X-ray is whether it's EBC, CBE or BCE.MOSFET/JFET would be indistinguishable from BCE and an IC could look like any of those.And you would need a frontal view for that.
Is this a THS4151 diff amp or something else? - Page 1
Forum section: electronics / projects

author: Kremmen
author_rank: Super Contributor
timestamp: December 11, 2016, 07:57:38 pm
content: I recently got donated some components among which is a tape of SOIC8's labeled only as "4151". There is a second line "0412" that i assume is the mfg date code.Nothing else save a round indentation and end notch for pin 1 orientation. Specifically, no mfg logo anywhere, just the 2 numeric codes.Has anyone used a THS4151 and did they look like that? It would be a win if these chips actually were THS4151's but may be useful even if something else.

author: daveshah
author_rank: Unknown
timestamp: December 12, 2016, 06:32:43 pm
content: Think TI SOIC8 parts always have the TI logo, and more codes that just the part number and date code - probably would have THS prefix at least.More likely a 4151 voltage to frequency converter, made by a few different manufacturers.

author: Kremmen
author_rank: Super Contributor
timestamp: December 12, 2016, 08:57:19 pm
content: Thanks, i was suspicious of the lack of logo as well. Most likely you are right and this is not a TI part but what you say.

author: daveshah
author_rank: Unknown
timestamp: December 12, 2016, 09:10:34 pm
content: Could always build a test circuit, and with a suitably low current limit it would probably be non-destructive even if it wasn't the expected chip.

author: Kremmen
author_rank: Super Contributor
timestamp: December 13, 2016, 11:08:59 pm
content: I got a good length piece of tape of chips so smoking a few won't matter. If it isn't a diff amp i don't mind burning them all since i have no use for V/f conerters.I actually decided to do just this, so we'll see.
Is this ADC input protection correct? - Page 1
Forum section: electronics / projects

author: baoshi
author_rank: Regular Contributor
timestamp: May 31, 2015, 02:56:41 am
content: Hi,I designed this ADC input protection circuit. For this case opamp output if something wrong will go max at 5V. The ADC input accepts full scale 600mV, and the input pin can only withstand 2V max.It sort worked but I'm not sure if it can be simplified.Please suggest.Thanks

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 31, 2015, 03:45:48 am
content: The knee won't be very sharp. You may lose accuracy towards the maximum.The threshold isn't well regulated, given that it's subtracting from another supply. You'd do better just using a voltage divider there.If it needs to handle ESD as well, you'd be better served with a different protection/clamping network. The 100n capacitor will absorb some ESD, but definitely won't clamp it below 2V.Why is the ADC limited to 2V? Supply? Why not use a schottky diode to its supply?Tim

author: Marco
author_rank: Super Contributor
timestamp: May 31, 2015, 03:55:54 am
content: With that much wiggle room trying to make the clamp that precise seems like a waste of components, just clamp at two diode drops ... you'd need some extreme temperatures before that is a problem.Do you really need the extremely low leakage current from the base emitter diode?

author: baoshi
author_rank: Regular Contributor
timestamp: May 31, 2015, 04:00:03 am
content: ah you are right. A voltage divider will just as good. The adc chip is MCP3911, supply 3.3V but analog pin max rating is 2V. Luckily ADC full scale is 600mv so I have plenty of room to bend the knee. Maybe put two diodes clamp is also good. I need to verify the linearity.

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: May 31, 2015, 04:31:43 am
content: you often have to balance clamping capability - V, I max against accuracy - leakage currents, nonlinear diode C effects on the signal

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 31, 2015, 04:59:54 pm
content: Weird, the input pins include -2 to +2V. Nothing else on the chip is negative. No Vss. Would be nice if they had a drawing of that input stage, but naturally, why would they?...Seems to me, you should drive the input from a precision op-amp, which can be arranged to clamp the input appropriately. This also adds another stage to separate possible ESD from whatever the input is.Tim

author: dom0
author_rank: Super Contributor
timestamp: May 31, 2015, 05:14:56 pm
content: Quote from: T3sl4co1l on May 31, 2015, 04:59:54 pmThe MCP3911 has an on-chip charge pump to power the AFE. It depends on MCLK (which is why it can reject the ripple of the pump so easily), however, and thus one should avoid putting negative voltages on the inputs if MCLK isn't present.
Is this an ac flyback? - Page 1
Forum section: electronics / projects

author: AutogolazzoJr
author_rank: Regular Contributor
timestamp: December 03, 2017, 05:49:37 pm
content: https://www.ebay.com/itm/8FT-056-Flyback-Transformer/121633377888?hash=item1c51ea0e60:g:k0EAAMXQvJVRWdTb:sc:USPSFirstClass!22003!US!-1Free food and beer for whomever answers first

author: madires
author_rank: Super Contributor
timestamp: December 03, 2017, 06:03:06 pm
content: It's a typical flyback for a CRT. It's not driven by AC, and presumably includes HV diodes for the output.
Is this Battery Bank in anyways safe. - Page 1
Forum section: electronics / projects

author: Isad
author_rank: Frequent Contributor
timestamp: May 30, 2015, 06:23:36 pm
content: So i bought this one on ebay for about 14$ and for some reasongo 2 well win for me.So i got my hands on the and as somebodywho like to know with what he is dealing i tore one down and well lookwhat i found the most cheapes way of puttin somthing together.Thattiny ic has to handle 1A and 2.1A Out and 1A charging and to makethings better they just put a lipo batter inside a aluminium case that is barealuminium.For 20Ah it doesnt do that thing in anyway i have aLG G3 wich has a 3Ah battery but only maneges to charge it2 times before its all dead i doubt it even has a 20Ah battery in it.My question is is this thing safe or what.

author: ManCave
author_rank: Regular Contributor
timestamp: May 30, 2015, 11:11:35 pm
content: Well, First of all,20,000mAh at 3.7V nominal = 44Wh NOT!So Let's assume that the 44Wh is correct, then you get <12Ah.Judging by the battery size, however, I would be surprised if it had more than 5-8Ah. And if the DC-DC converter is 85% efficient, you end up with 4.2 - 6.8Ah which seems about right for what you're saying.Size of the components is not important. More important is how well is the heat taken away from them and how well is the PCB laid out.is it safe? ..I doubt it! These things are designed down to the last cent of cost saving and the no-name battery is likely to be of very poor quality. Although chances are the worst you will experience is quick deterioration of the battery life.btw, using punctuation really helps people to read your question. ...perhaps one of the reasons why you had no answer to this fairly obvious post.

author: Isad
author_rank: Frequent Contributor
timestamp: May 31, 2015, 08:35:58 am
content: Quote from: ManCave on May 30, 2015, 11:11:35 pmYeah these thing are cheap i just tested the battery and lets say it supplys 7A in a 1 ohm load (yeah probably shouldnt have done that) but was justa 2 sec test so yeah.This one is probably gona end up supplying somthing like a rpi or arduino wich ever come first but the other i migth just tear it down to.English is not my 1 language so speaking it with punctuation isnt really easy .Happens a lot thansk for the help tho.

author: mikerj
author_rank: Super Contributor
timestamp: May 31, 2015, 09:32:41 am
content: Quote from: ManCave on May 30, 2015, 11:11:35 pmHard to get a sense of scale from the pics, but I'd be surprised if it was even a 2 Ah cell. Typical shoddily built cheap crap with lies printed on it.

author: Isad
author_rank: Frequent Contributor
timestamp: May 31, 2015, 09:59:28 am
content: Quote from: blueskull on May 31, 2015, 09:41:47 amHmm well idk here i have never taken 1 but even so i would bealive that that rule applys here too.
Is this Charger/Pulse schematic fundamentally correct? - Page 1
Forum section: electronics / projects

author: nsled
author_rank: Contributor
timestamp: May 02, 2023, 09:10:46 am
content: As attached, Is this fundamentally correct?I have everything short the power supply and voltmeter.

author: TopQuark
author_rank: Frequent Contributor
timestamp: May 02, 2023, 09:15:37 am
content: If you have to ask, perhaps you shouldn't do it?Edit: I don't want to gatekeep and tell you what to do and what not to do. But just for some context, your 5kV 40uF cap holds 500J fully charged, roughly the same energy as a 9mm bullet exiting a barrel (https://en.wikipedia.org/wiki/9%C3%9719mm_Parabellum).If that kind of energy gets released at the wrong place at the wrong time within your circuit due to say faulty wiring, are you really prepared for that kind of bang and surprise?
Is this circuit adequate to interface a uC with a dc motor using an optocoupler? - Page 1
Forum section: electronics / projects

author: FBMinis
author_rank: Regular Contributor
timestamp: April 27, 2024, 11:41:23 am
content: I would like to make a device using an esp32c3 and an optocoupler to allow me to actuate a separate device comprised of a motor running from a different power source (4.2V, 6V or 12V).The esp32c3 runs from 2x AA alkalines and would wake up periodically to run the motor for a minute, then go back to sleep.What should I change in the attached circuit?https://tinyurl.com/28jr5j6kThank you.

author: FBMinis
author_rank: Regular Contributor
timestamp: April 27, 2024, 05:22:58 pm
content: I re-drew the schematic, hope it's clearer.the water dispenser is comprised of an 18650 cell, circuit board and motor. The circuit board has a uC that handles USB charging and that enables/disables the motor when its button is pressed.I want to enable/disable the motor periodically with an ESP32C3 through an optocoupler.

author: Retirednerd2020
author_rank: Regular Contributor
timestamp: April 27, 2024, 07:40:41 pm
content: I think you can eliminate one of the FET circuits and just put the switch in parallel with the output transistor of the optoisolator, making a wired-or. You could do this with an N or P fet, whichever is cheaper. The opto-coupler isn't really necessary because the FET can be the "translator" between the independent power sources. Only the ground would be shared. You have choices.

author: FBMinis
author_rank: Regular Contributor
timestamp: April 30, 2024, 01:31:10 pm
content: The "fet with switch" I included in the schematic next to the motor represent the microcontroller on the water dispenser, which turns ON/OFF the pump when its button is pressed.

author: Terry Bites
author_rank: Super Contributor
timestamp: April 30, 2024, 06:27:55 pm
content: You can just put the manual switch across D and S. That saves you a MOSFET.Watch out for the opto current. About 8mA from your AAs.A simple latch circuit may be better. A brief pulse at the opto toggling the load on and off.Note the emitter follower connection used to change the sense and to speed up the edge seen by the FF.A CD4013 is about $0.50The capacitor, resistor and diode connected to the 4013 make sure it powers up in the off state.

author: FBMinis
author_rank: Regular Contributor
timestamp: May 02, 2024, 11:24:26 am
content: Thank you so much for taking the time, going to give it a go

author: FBMinis
author_rank: Regular Contributor
timestamp: May 09, 2024, 07:13:53 pm
content: I got it working like in the attached diagram. Do you see any possible point of failure?
Is this datasheet wrong? - Page 1
Forum section: electronics / projects

author: smbaker
author_rank: Regular Contributor
timestamp: January 05, 2019, 08:35:42 pm
content: I built myself some USB power supplies using Figure 10 fromhttps://www.mouser.com/ds/2/631/ACT4533A_Datasheet-346085.pdf,which is supposed to have a current limit of 2.4A. Measuring the supplies I built, I'm getting a current limit of around 3A.Here's a description of setting the current limit:QuoteUsing ohm's law, I'm calculating that the recommended 7.87K resistor would yield a current limit of 2.94A (consistent with the ~ 3A that I'm seeing) and that for 2.4A current limit the appropriate value would be 9.63K.Can someone check my math and verify that I'm not being an idiot?Scott

author: ebastler
author_rank: Super Contributor
timestamp: January 05, 2019, 08:56:24 pm
content: I guess they mean that the power supply is designed to supply up to 2.4A reliably and robustly. Then all components will provide for some headroom beyond that current; and don't want your current limiter to kick in at exactly 2.4A, but a bit above that limit. So, no real contradiction.

author: smbaker
author_rank: Regular Contributor
timestamp: January 06, 2019, 01:05:38 am
content: Quote from: ebastler on January 05, 2019, 08:56:24 pmHmm, I suppose you could read it that way.The description of the IC is that it provides constant voltage and/or constant current regulation, so my expectation reading that example in the datasheet is that it would transition to constant-current mode at 2.4A.I should find a few other chargers around the house and see how they behave when they reach their stated current limit. Maybe having it limit at 25% over the stated rating is standard practice.

author: Wimberleytech
author_rank: Super Contributor
timestamp: January 06, 2019, 02:49:56 am
content: QuoteYour math is correct. Moreover, the datasheet figure gets closer to the 2.4 number as shown in my attached image.

author: David Hess
author_rank: Super Contributor
timestamp: January 06, 2019, 03:19:44 am
content: ±7.5% CC AccuracyNo other accuracy specifications are given for Iset and current ratio. It is not meant to be a precision constant current source.
Is this multiplexer or a direct equivalent available in DIP? - Page 1
Forum section: electronics / projects

author: Chris Wilson
author_rank: Super Contributor
timestamp: January 28, 2018, 07:54:00 pm
content: https://www.onsemi.com/pub/Collateral/74FST3253-D.PDFA 74FST3253? I would prefer DIP for bread boarding experiments. Thanks. I know you can buy converter PCB's but not ideal for what I want.

author: DC1MC
author_rank: Super Contributor
timestamp: January 28, 2018, 08:21:48 pm
content: Not really available in classic DIP pachage, your best and cheapest bet is some 4052 compatible chip, like:https://www.tandyonline.com/74hc4052-dual-4-channel-analog-multiplexer-demultiplexer.htmlCheers,DC1MC
Is this power supply good for a newbie Digimess DP3005 - Page 1
Forum section: electronics / projects

author: Flavour Flave
author_rank: Regular Contributor
timestamp: February 22, 2011, 05:21:46 pm
content: Hi I'm considering buying ex-demo Dimess DP3005 benchtop powersupply. Comes with six months warranty. Bit less than half retail price. Selling for £100Are they a good make?Can be operated in constant voltage or constant current modesHere are the specs.No. of outputs. SingleNo. of stored outputs. 3Output voltage 0-30VOutput current 0-5AResolution V:10mV A:10mALine regulation CV:<5mV CC:<5mALoad regulation CV:<5mV CC:<5mARipple & noise CV:<1mVrmsCC:<3mArmsLink to pdf herehttp://www.digimessinstruments.co.uk/datasheets/english/dpserieseng.pdfThankyou for any adviceYep I've posted this in the wrong section.

author: saturation
author_rank: Super Contributor
timestamp: February 22, 2011, 06:16:05 pm
content: They look good to me, programmable ease, yet linear supply. The only con is the brand name, I'm not familiar with them.The website suggests they used the name Grundig in the past, not sure how related they were; Grundig is a brand for consumer electronics.The product listing has some items I recognize at least externally, as Chinese products sold under many different names.http://www.digimessinstruments.co.uk/products1/For example, in the pic the HY3003, look just like the Mastech PSU by the same number, HY3003.http://www.digifail.com/hardware/hy3003.shtml

author: Flavour Flave
author_rank: Regular Contributor
timestamp: February 22, 2011, 08:14:05 pm
content: Well I'm a bit hasty. After looking at some others I bought it anyway about half an hour ago. Well I suppose I paid extra for the 3 programmable memories which will be useful.Well I will check it out with my Rigol DSO when I get it in couple of days and post the screenshots in this thread. Thanks for the replies.Ps Well its bloody about time I stopped writing "well" so many times and develop a better writing style
Is this really a 1/16W resistor? - Page 1
Forum section: electronics / projects

author: zapta
author_rank: Super Contributor
timestamp: November 05, 2014, 06:31:03 pm
content: I am looking at this 100M 0402 1/16W resistor.http://www.digikey.com/product-detail/en/HMC0402JT100M/HMC0402JT100MCT-ND/2683714Max working voltage is 50V so clearly it cannot handle 1/16W.

author: CrashO
author_rank: Unknown
timestamp: November 05, 2014, 06:43:03 pm
content: The wattage is saying something about the dissipation, not the vmax. At 5V 1/16W gives you 0.0625/5=12.5mA max. Which is normal for a 0402 sized resistor.1/16W / 50V already leaves you with just 1.25mA max, which is why they specify it as a max. (you're planning on powering mains on 0402 resistors?..

author: coppice
author_rank: Super Contributor
timestamp: November 05, 2014, 06:43:58 pm
content: Well it can't handle 50V continuously, but it can certainly handle short pulses of 50V.

author: zapta
author_rank: Super Contributor
timestamp: November 05, 2014, 06:51:53 pm
content: Quote from: coppice on November 05, 2014, 06:43:58 pmBut at 50v gets it to less than 1mw so clearly it cannot handle 1/16w.

author: zapta
author_rank: Super Contributor
timestamp: November 05, 2014, 06:53:42 pm
content: Quote from: CrashO on November 05, 2014, 06:43:03 pmBut 1.25ma is much more than 50V on a 100M resistor. In other words, it can never reach even closer to 1/16W.

author: Rufus
author_rank: Super Contributor
timestamp: November 05, 2014, 06:53:52 pm
content: Quote from: zapta on November 05, 2014, 06:31:03 pmNeither could any similarly rated part with resistance above 20k.Do you seriously expect them to calculate and specify hundreds of different voltage limited power dissipations?It is a package dissipation limit.

author: Zero999
author_rank: Super Contributor
timestamp: November 05, 2014, 07:23:27 pm
content: Yes it's the package dissipation limit of course.Resistors have a maximum voltage rating which is more important than the maximum power rating at high resistance values and shouldn't be exceeded, otherwise strange/bad things happen such as the resistance is reduced, arcing and smoke.The maximum power rating can be exceeded for short periods of time, as long as the voltage rating isn't exceeded.

author: Seekonk
author_rank: Super Contributor
timestamp: November 05, 2014, 09:02:16 pm
content: Unless you live in China, that is the maximum voltage the resistor should see to prevent sparkover. I have this 240V power meter from you know where that uses a 150V resistor for the voltage sense. You can get away with a lot of stuff for a while. I get a lot of stuff donated to me that has a 1/4 W CF resistor in series with a cap in a line operated supply. CF resistors are really prone to opening with surges even though the power is very low. Hard to find carbon comp are quite robust with surges.
Is this some kind of timer of something? - Page 1
Forum section: electronics / projects

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: February 24, 2020, 07:00:33 am
content: I found this and when I turn it on the ”work” light flashes for a bit and then the smaller relay clicks and the ”start” light glows. Here are some pictures:The buttons and pots and the switch seem to do nothing. There is a 1 k resistor across the sensor input and the diode for the ”KT

author: james_s
author_rank: Super Contributor
timestamp: February 24, 2020, 07:02:03 am
content: Maybe they're just not showing up on my phone but I don't see any pictures?

author: ataradov
author_rank: Super Contributor
timestamp: February 24, 2020, 07:24:04 am
content: This is a device to control the speed of the conveyor belt.Info in Russianhttps://td-kmaelmash.ru/p331019660-ustrojstvo-uks-apparat.htmlNote that I just googled the info from the label. I have no idea what it actually does.They are still being manufactured and sold. And they are not all that expensive, like $50.
Is this the date code for a Nichicon capacitor (pic attached) - Page 1
Forum section: electronics / projects

author: xrunner
author_rank: Super Contributor
timestamp: January 27, 2016, 08:16:53 pm
content: I've researched the case markings and I couldn't find a definitive answer. Is that the date code as shown in the attachment, i.e. 1986 - week 08?Thank you.

author: retiredcaps
author_rank: Super Contributor
timestamp: January 27, 2016, 10:18:04 pm
content: Quote from: xrunner on January 27, 2016, 08:16:53 pmSounds right to me.
Is this the right fiber optic keystone for this connector - Page 1
Forum section: electronics / projects

author: drakejest
author_rank: Regular Contributor
timestamp: July 23, 2021, 04:46:46 pm
content: The fiber optic cable in my home typically goes through a wall from the ISP, it looked ugly so i decided to place a wall panel that has a blank keystone on it,I would like to do some sanity check before i buy if this is the right fiber optic keystone for these connectorsHere are the images of the connector.https://ibb.co/RHk3NtFhttps://ibb.co/JBh1v42https://ibb.co/gmBZGbpIm buying some other stuff from this store, so it would be great if this is correct.https://www.digikey.com/en/products/detail/hellermanntyton/SCSMINSERT-W/9956960Is this keystone a male-female? male at the back female at the front? so i wont have to call somebody to splice the cable

author: ConKbot
author_rank: Super Contributor
timestamp: July 24, 2021, 02:41:26 am
content: Looks like the right part by the datasheet and PN, digikey listing is incorrect, listing it as an ST, but errors in their listing isn't that rare.As far as what kind of cable, there are no cord mount sockets for fiber that are common enough to worry about. If there are, they most likely consist of a plug with a coupler integrated into the connector.Fiber connections are a ceramic ferrule with a hole in the center, that the fiber gets secured in, cleaved offs and polished with a slight dome/radius to it. The coupler holds the mating plugs coaxial with each other with another different ferrule and the core of the fibers themselves touch, with the spring mechanism in the connector applying force to hold them together.Given the fiber core is around 9 microns in singlemode fiber, it doesn't take much dirt to interfere, either by obscuring the core, or spacing the connector faces apart, keep them clean, don't touch the ends, get a can of air duster at minimum to blow them off. If there is no oil on the end, dirt wont stick and can be blown off.You'll install the keystone and run a SC single mode simplex patch cord from the wall to your modem. Look at the length of cord you have available to you now, you should see something like "9/125 OS2" written on it, if so, that's just bog standard single mode fiber, and a patch cable will be easy to find.

author: drakejest
author_rank: Regular Contributor
timestamp: July 24, 2021, 02:19:57 pm
content: Thank you! will go ahead and place my orderThis is my first time playing with fiber optic connection so i dont really know what are the common connectors
ISL9V5036P3 ignition IGBT - Page 1
Forum section: electronics / projects

author: LukeW
author_rank: Frequent Contributor
timestamp: November 06, 2016, 03:06:28 pm
content: https://www.fairchildsemi.com/datasheets/IS/ISL9V5036S3.pdfIn a typical automotive ignition application, where the coil is driven by the IGBT collector on the low side, are any external components needed?Suppose the gate drive is 3.3V or 5V from a microcontroller. It claims no external components are needed - is this really optimal?A series gate resistor? Weak pull-down on the gate? Or some sort of active gate driver to charge and discharge the gate faster?What about the collector side - any sort of flyback snubber etc desirable across the ignition coil?

author: langwadt
author_rank: Super Contributor
timestamp: November 06, 2016, 03:15:58 pm
content: Quote from: LukeW on November 06, 2016, 03:06:28 pmpulldown and series resistor is build in and it clamps at ~400V so you shouldn't need anything more, but it seems to only be spec'ed for 5V drive

author: MartinX
author_rank: Regular Contributor
timestamp: November 06, 2016, 06:15:45 pm
content: You are supposed to have 1k gate resistor as the data sheet curves tell you and 5V drive that is all, this is a very specialized component optimized for one thing only. Depending on the ignition coil you want to drive it may be beneficial to add a capacitor across the coil like in a classic breaker-condenser system, most often if you use a coil made for breaker operation.
ISO 13849-1; 4.6.2; "computer-based tools with confidence from use" - Page 1
Forum section: electronics / projects

author: uwe__
author_rank: Newbie
timestamp: December 01, 2022, 09:34:04 am
content: hi,what is meant in the norm by "computer-based tools with confidence from use"?Does it require a tool validation similiar to IEC 61508-3 7.4.4 (T1-T3) or ISO26262-8 chapter 11(TCL)?If so, which tools need to be included in that?The used compiler (Probably requires buying a certified one since testing seems too extensive)The Used IDE?Support tools required for tests like PCAN-Drivers?The used test framework?Is there a guideline to what needs to be tested and to what extent?
ISO 13849-1; Category 2 architecture - Page 1
Forum section: electronics / projects

author: uwe__
author_rank: Newbie
timestamp: December 01, 2022, 09:43:13 am
content: hi,in the norm for category 2 (https://machinerysafety101.com/wp-content/uploads/2018/05/Cat-2-Block-Diagram.jpg) the test equipment (TE) is drawn as a seperate function block with a seperate output.Can one single core safety microcontroller do the normal output and the monitoring or is it required that the monitoring is done by an external controller?
Isolated 12V output replace with IGBT driver? - Page 1
Forum section: electronics / projects

author: mrburnzie
author_rank: Regular Contributor
timestamp: February 10, 2021, 03:38:07 pm
content: I'm looking to find the best solution for my problem.I have a system with 16 outputs, P-Channel mosfets that are mostly used to drive relays, but can be used to power anything that is 12V.The output voltage is 12V and the needed current is max 2A.I want to isolate my design. First I though of optocouplers of course, but I'm restricted by space.Is it a good idea to use an IGBT driver (https://lcsc.com/product-detail/IGBT_AVAGO-Broadcom-Avago-HCPL-3120-500E_C36986.html)?It is isolated, it can handle 2A output.An IGBT driver either connects the output to the high voltage and then connects it to the low voltage (in my case 0V), which is the same as my setup with the mosfets, where when I give it voltage, it connects the load to 12V.Is this a good option or should I go the traditional way of optocouplers and mosfets?

author: capt bullshot
author_rank: Super Contributor
timestamp: February 10, 2021, 03:51:34 pm
content: You'd have to double check the data sheet. The output current rating of these drivers is typically pulse current (to charge the IGBT gate), not continuous. So depending on the particular driver your application will exceed its maximum power dissipation. Hint: they have various kinds of output stages some of them dropping a volt or two in on state at rated current, this will generate too much heat if current flow is steady.

author: mrburnzie
author_rank: Regular Contributor
timestamp: February 10, 2021, 03:53:41 pm
content: Yeah, makes sense. That is the exact consern I had.

author: PartialDischarge
author_rank: Super Contributor
timestamp: February 10, 2021, 04:18:46 pm
content: As captbullshot mentioned that current is given for a 10us pulse at 0.2% duty cycle. So pretty much useless for anything else
Isolated AC "Tester" Circuit for Microcontroller Interfacing? - Page 1
Forum section: electronics / projects

author: Dave8266
author_rank: Contributor
timestamp: September 06, 2025, 01:20:44 am
content: Hey folks, I'm pondering circuits for detecting AC mains wiring correctness, but with an isolated microcontroller interface.Conceptually, I would like to replicate the functionality of those ubiquitous hardware store 3-lamp neon receptacle tester, which can tell if an outlet is wired correctly or if any two wires are swapped, open, etc, but would also like to incorporate a simple AC voltage measurement.The consumer devices which do this are relatively cheap, and the circuits for the human-readable testers are straightforward (eg,https://electronics.stackexchange.com/questions/476462/circuit-analysis-of-an-outlet-tester).However, in replicating this digitally and with isolation, for a logic circuit to ingest instead of humans, the circuits end up being much more involved. A trio of AC optocouplers, the associated current limiting resistors, maintaining HV separations, pull-ups, etc, and then either transformers and isolated ADCs, or supervisor type chips, etc, for the voltage measurements. On top of that, since it's AC, you add the timing requirements - either needing to separately sense the zero crossing to know when to sample (for both functions of the circuit), or to sample the ADCs at high speed and do the filtering or timing deductions in software.Does anyone know of any off-the-shelf solutions for this type of application? Or any specialty ICs that might do parts of this, in a more compact or elegant way than discrete functional blocks?Thanks in advance

author: ledtester
author_rank: Super Contributor
timestamp: September 06, 2025, 02:17:02 am
content: Would this work for you:Take an outlet tester and attach color sensors to each of the three bulbs. The microcontroller would have its own battery for power and use the color sensors to "read" the bulbs.Possibilities for the sensors could be phototransistors/-diodes or even color sensor modules built around chips like the TCS3200.To read voltage, there are power meters which have an isolated serial interface. You can find a lot of them on Aliexpress like the one described in this video:Modifying the Peacefair PZEM-004T AC Comms Module (with schematic) -- TheHWCavehttps://youtu.be/qRsjsenvlJA
Isolated Buck -- Just add coupled inductors?  (AN-2292) - Page 1
Forum section: electronics / projects

author: klr5205
author_rank: Regular Contributor
timestamp: February 10, 2016, 04:04:59 pm
content: I was reading through TI's Appnote AN-2292 "Designing an Isolated Buck (Flybuck) Converter" and I was a little surprised by how straightforward it all seemed. Basically the filter inductor of your traditional buck converter is replaced with a transformer which provides isolated outputs that track the primary output according to the turns ratio.What are the limitations to this approach? Are there any "traps for young players" to look out for?http://www.ti.com/lit/an/snva674b/snva674b.pdf

author: chris_leyson
author_rank: Super Contributor
timestamp: February 10, 2016, 04:18:04 pm
content: You've got to put a current limits on the auxiliary outputs, without it if you short any of the auxiliary outputs the buck inductor gets shorted too and say goodbye to your buck controller.
Isolated DAC for Higher Voltage Output using series connection. - Page 1
Forum section: electronics / projects

author: Arsh ahmad
author_rank: Regular Contributor
timestamp: October 11, 2024, 05:24:56 am
content: Hi,I am building a photodiode biasing circuit that requires 90volts DC, I initially wanted to use LT3482 APD boost convertor, but after analyzing it I came to know that it takes jumps in voltage, according to APD vendor, Fastest I can ramp up the voltage is less than 2V/sec.I was thinking of making two 40 volts isolated DACs and then putting them is series to achieve the same higher voltage along with precise voltage control. What are possibilities of making an isolated DAC circuit at this high voltage.

author: moffy
author_rank: Super Contributor
timestamp: October 11, 2024, 05:53:17 am
content: You could use a simple RC startup for a linear regulator to bias the APD and limit the dv/dt, APDs don't normally consume large currents.

author: Arsh ahmad
author_rank: Regular Contributor
timestamp: October 11, 2024, 06:16:30 am
content: I could use one but that will not give precise control on the voltage, I a same lot of the APD they differ in breakdown voltages and these voltages can be very precise , sometimes even in the orders of 100mV. With RC circuit on the output of the regulator I will loose that control for precise voltages.I also tried to use high voltage op-amps to make an LDO but the problem with most HV opamps is the gain, they are mostly Unity gain stable.

author: moffy
author_rank: Super Contributor
timestamp: October 11, 2024, 06:46:33 am
content: You might want to look through this discussion:https://www.eevblog.com/forum/projects/relatively-high-voltage-precision-dac-amplification/

author: Ian.M
author_rank: Super Contributor
timestamp: October 11, 2024, 07:53:17 am
content: A 0-100V digitally controlled source consisting of a x20 non-inverting high voltage OPAMP stage driven by a 0-5V DAC is certainly viable, though it may be simpler to go to a two stage design especially if using a lower voltage DAC and use a conventional OPAMP first stage to get the signal up to 20 or 30V swing to limit the gain required in the high voltage stage.Digikey have an application note with sample circuits:https://www.digikey.co.uk/en/articles/control-amplify-high-voltages-effectively-high-voltage-op-amp

author: Arsh ahmad
author_rank: Regular Contributor
timestamp: October 11, 2024, 10:45:06 am
content: Quote from: moffy on October 11, 2024, 06:46:33 amThanks for linking with the thread, from there I got this ADHV4702-1, this one is a very versatile OPMAP, after doing some LT simulations this can easily solve my problem,Good thing is that at lower frequencies There will be a high gain, so I can use a 10v or 5 Volt DAC for the input, Also I don't need a negative supply of -100V since it can be used with asymmetric supply, so I can put a -5 volt negative and 100V positive boost convertor.I wanted to make this board small to fit in a tiny enclosure, these components will help to reduce the footprint of the board
Isolated DC/DC 18V - Page 1
Forum section: electronics / projects

author: luky315
author_rank: Regular Contributor
timestamp: March 08, 2014, 05:08:01 pm
content: I am searching for an isolated 200mA DC/DC converter with 5V input and 18V output. Are there any modules with adjustable output power which I overlooked or is a discrete solution bether? There are analog circuits on the isolated side so low output ripple is prefered. Any suggestions?

author: Psi
author_rank: Super Contributor
timestamp: March 08, 2014, 09:16:19 pm
content: 18V is an uncommon voltage for a potted prebuilt module and small adjustable prebuilt modules are usually pretty expensive.However there are some cheap china switchmode pcb modules available all over ebay/aliexpress and elsewhere.They exist in boost, buck or sepic versions. The boost version would be suitable for 5V to 18Vhttp://www.aliexpress.com/item/5A-Current-Input-DC-Boost-Adjustable-Converter-Step-Up-Power-Supply-090439/554143355.htmlI've used the sepic and buck version and they do work, but i've not tested the ripple so i dunno how well it would work for you.Perhaps you could set it to 21V and use a 18V linear reg to smooth it out.Another option is multiple modules in series. two 9V or a 5V and 12V.5v and 12v modules are dirt cheap and easy to find.If your analog circuits are a little susceptible to noise you really should go with a linear reg as the final stage.

author: macboy
author_rank: Super Contributor
timestamp: March 10, 2014, 01:49:14 pm
content: Quote from: Psi on March 08, 2014, 09:16:19 pmThe problem with those is that they are not isolated. They share a common ground with the input side. Isolated modules do exist; they use a transformer based circuit instead of a simple boost with an inductor.Depending on the power required, it may not be difficult to rig something up with a small transformer and an oscillator like a 555 timer. The output voltage will be determined by the turns ratio instead of being actively regulated. Then, based on your requirements, you may want a low-power, low quiescent current regulator (e.g. 78L18) to regulate the output.

author: Psi
author_rank: Super Contributor
timestamp: March 10, 2014, 10:26:09 pm
content: ops yeah, forgot those modules aren't isolated.In that case maybe just use an isolated 5v and 12V in series, that would be pretty easy.

author: nctnico
author_rank: Super Contributor
timestamp: March 10, 2014, 11:37:26 pm
content: How about 5V to +/-9V? That gives 18V with a mid level reference.
Isolated digital input with switchable pullup resistor - Page 1
Forum section: electronics / projects

author: jars121
author_rank: Regular Contributor
timestamp: November 27, 2023, 02:26:34 am
content: Hi all,I'm working on a DAQ design, whereby I need to receive X number of low speed (<10kHz) digital signals (across X number of input connector pins). I would like to isolate the signals from the rest of the board.I have an existing design (shown below) which addresses half of this requirement; the below works where the switched input is switching to an external VDD/Vref, providing a positive voltage to the DAQ input. The resistor divider, diode and Zener are chosen to ensure a safe ~3V input to the Si838x isolator across the expected voltage range and to minimise any reverse polarity issues.I would also like to accommodate a second use case, whereby the external electronics to which the DAQ is interfacing instead switches the input to ground. In this scenario, I'd enable a pullup (via MCU GPIO) on the input line to an isolated 12V supply, which would provide a 3V3 output from the Si838x isolator when the switch is open, with the signal line pulled to ground when the switch is closed. I.e. the logic on the MCU side would be inverted (note that the diagram above does not show the inverted signal). Here's an initial pass at what this might look like:The Si838x requires at least 1mA of input current and a voltage of at least 2V to register a logic HIGH. I'd like to be able to safely accommodate input voltage between 6-24V (with protection against spikes up to 80V; perhaps I need (a) TVS diode(s)?). The R3 value of 4.7k will keep the switched ground current to ~2.5mA which should be fine for the source/external electronics.Does the above seem reasonable? Have I missed, misunderstood or overlooked anything?

author: TGPCB
author_rank: Newbie
timestamp: April 28, 2025, 06:32:52 pm
content: Did you ever build and test this? What were the results?Does anyone else have any comments on the OPs circuit?

author: PGPG
author_rank: Frequent Contributor
timestamp: April 29, 2025, 12:31:55 am
content: Quote from: TGPCB on April 28, 2025, 06:32:52 pmI suppose OP forgot about this circuit years ago.

author: Terry Bites
author_rank: Super Contributor
timestamp: May 03, 2025, 07:32:54 pm
content: I'd use the diodes to create an OR function then pot down the output before the zener clamp. Set R1 and R2 proportionately.Zeners are not so great here, slow and current dependent clamping voltage. Regular signal didoes will do the job.