hybridfree/eevblog-posts huggingface dataset:
5% Crude uCurrent Mockup is shockingly accurate!  - Page 1
Forum section: electronics / projects

author: BiOzZ
author_rank: Regular Contributor
timestamp: September 29, 2013, 04:40:49 pm
content: ok so im at home and i needed a way to measure the current draw of a current project for work and i wanted to do it in the most basic of ways possible so i just stuck my cheap mastech in to uA mode and measured it on that ... the impedance was way to high for the 3.3v logic and got way too much voltage dropi do not own a uCurrentas im broke(tho id love onewhen i get the cash!)so i scoured the parts bin and i had a left over ICL7650SCPA (datasheethttp://www.intersil.com/content/dam/Intersil/documents/fn29/fn2920.pdf) 2mhz 'super' chopper amplifier ... massive overkill but ok!i made this simple circuit based entirely off the uCurrnet (thanks dave!)And with all off the shelf 5% resistors and cheap jumpers on a breadboard with only 1 decoupling cap i got these results!Tested with a voltagestandard.com calabrated voltage and current standard thats only like 3 monts in cal ... for the 1ma test i used the 1ma 2ppm source on it, for the 50 and 500 uA tests i used the 2ppm resistors (the 10k and 100k) and the calibrated 5v out^1mA^500uA^50uAIM NOT SAYING THIS IS SOMETHING TO MAKE FOR PRECISION I SIMPLY GOT LUCKYWhy does this work? Undeniable proof that there is a god?no like everything else it can be explained with science!for one i got an AMAZING opamp in there ... there about $6 a peace and in this setup has an offset at the lowest voltage i can measure ... 0.0mv andyes my meter was calibrated(manually) to have the voltage as dead on (tested with the voltagestandard.com standard but it was calabrated in my unis cal lab)Secondly all the resistors are from one lot and have about the same resistance deviationThird i got lucky with my 100k and 1k having a ratio of 99,100 (not exactly but with my rough math)Forth i have central air so the temperature remains stableFifth its powered off batteries and my house has very low ambient noiseAGAIN DONT TAKE THIS AS AN EXCUSE TO SWAP OUT YOUR 0.5% RESISTORS FOR 5% ... i was LUCKYand yes thats an end table ... dont ask XP

author: babysitter
author_rank: Frequent Contributor
timestamp: September 30, 2013, 08:17:13 am
content: Congratulations for this result!Its way better to have this tool than to not having it, especially when being broke.Seems that your parts just fit together very well and a lot of errors somewhat canceled out. I hope they keep to be like this after soldering to a more permanent thingie.The only enemies you might have are changing ambient or aging, it might be further off in some years but you can start worring about this when it happens.If you use 5% resistors for this then you will probably also use some for your projects, so when measuring power consumption, the DUT might well change more than your measurement rig, without being a problem.BRHendrik
5 minute build 24XX/24CXX series EEPROM programmer (9 pin serial) - Page 1
Forum section: electronics / projects

author: glossywhite
author_rank: Regular Contributor
timestamp: January 10, 2011, 12:04:14 am
content: Found a VERY poor diagram of a VERY simple (and working) 24XX/24CXX series EEPROM programmer, so I re-drew it... just not AS badly. I built this in five mins flat, and it works EVERY TIME on 24 series EEPROMS, with "PonyProg" software:

author: PeterG
author_rank: Frequent Contributor
timestamp: January 10, 2011, 02:40:35 am
content: Looks a lot like a JDM programmer. Maybe the first version of it anyway.....

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: January 10, 2011, 05:27:37 am
content: A true RS-232 com port has +12/-12 volt levels instead of 0/5 volt levels. Newer computers sometimes have 5 volt versions but this circuit looks like a quick way to damage chips.

author: glossywhite
author_rank: Regular Contributor
timestamp: January 10, 2011, 01:05:32 pm
content: Quote from: Jon Chandler on January 10, 2011, 05:27:37 amWell it works on my pc... can't guarantee it though.

author: Mechatrommer
author_rank: Super Contributor
timestamp: January 10, 2011, 02:24:27 pm
content: Quote from: glossywhite on January 10, 2011, 01:05:32 pmcan you check your rs232 with oscilloscope? to see what voltage level is your rs232? so we will not have any chip damage report.

author: Unknown
author_rank: Unknown
timestamp: January 10, 2011, 02:26:01 pm
content: IIRC the RS-232 spec is something like min. +/-3V and (absolute) max. +/-25V. Adding something like a MAX232 would probably be a good idea.Does it work with USB-serial interfaces? I don't think all(most?) of them implement handshaking.

author: glossywhite
author_rank: Regular Contributor
timestamp: January 10, 2011, 02:36:50 pm
content: I don't currently have an oscilloscope - I am waiting on one from an old friend. I didn't realise the voltage spec was so broad; I must have a low voltage on my PCs COM, then.

author: Mechatrommer
author_rank: Super Contributor
timestamp: January 10, 2011, 06:56:43 pm
content: Quote from: glossywhite on January 10, 2011, 02:36:50 pmsend something high, and measure with multimeter Vdc.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 11, 2011, 01:14:09 am
content: Quote from: alm on January 10, 2011, 02:26:01 pmThey usually do implement handshaking, but the packetised nature of USB means that relative timings can get very screwed.

author: Mechatrommer
author_rank: Super Contributor
timestamp: January 11, 2011, 06:02:05 am
content: Quote from: mikeselectricstuff on January 11, 2011, 01:14:09 amfrom my limited knowledge, the handshaking is done in chip level, not the chip's serial out pins. regarding timing, the detailed eeprom datasheet explanation can indicates if usb implementation is possible. and again from my limited knowledge, if its less than 64Bytes data at a time (62 actually), i think its possible, since i've done it with the ft232.
5-phase stepper motor driver SI-7510 - Page 1
Forum section: electronics / projects

author: xzswq21
author_rank: Frequent Contributor
timestamp: September 13, 2022, 08:01:15 pm
content: HelloI wanted to build a 5-phase stepper motor controller using SI-7510 but the IC is obsolete!https://www.digikey.com/en/products/detail/sanken/SI-7510/4454412?s=N4IgTCBcDaIAQGUCSBaA7AVgIwAYQF0BfIAI checked the Sanken website but I couldn't find any equivalent. what should I do?Thanks

author: thm_w
author_rank: Super Contributor
timestamp: September 13, 2022, 10:46:53 pm
content: I would use a more commonly available two phase stepper motor if possible.Or buy something off the shelf, and see what they do.https://catalog.orientalmotor.com/viewitems/cvd-5-phase-stepper-drivers/cvd-5-phase-stepper-motor-drivershttps://www.aliexpress.com/item/3256804112336673.html

author: twospoons
author_rank: Frequent Contributor
timestamp: September 13, 2022, 11:54:42 pm
content: There's nothing stopping you doing the phase control with a microcontroller or an FPGA - its just a bit more work than using an off-the-shelf driver.Quote from: thm_w on September 13, 2022, 10:46:53 pm5phase steppers have some nice properties - they seem to run much faster than 2-ph before they miss steps, and the ones I have are 1000 steps per rev - without microstepping.

author: thm_w
author_rank: Super Contributor
timestamp: September 14, 2022, 12:49:48 am
content: Quote from: twospoons on September 13, 2022, 11:54:42 pmThey do (below), but OP hasn't given any specific reason why they would need them yet." Replacing a 2-phase motor with a 5-phase motor will not increase your positioning accuracy, but it will reduce resonance, vibration, and noise. If you are trying to increase positioning accuracy, we would suggest you try one of our high resolution type step motors which would have a 100 teeth rotor."https://www.orientalmotorforum.com/viewtopic.php?t=672
5 pin connector, safe, low cost 300V (one pair 240Vac, one pair 120Vac, < 10A - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: January 02, 2024, 12:06:42 am
content: Any suggestions for a 4 or 5 pin plug/receptacle:This is for a control cable between a control panel and a machine. Indoor, no requirement for water or fluids etc.SafeLow costSome sort of lock so it won't fallout if vertical mounted300V (one pair 240Vac, one pair 120Vac, 5A minimumChassis mount and free hanging for cable

author: themadhippy
author_rank: Super Contributor
timestamp: January 02, 2024, 01:13:44 am
content: blue 5 pin ceeform (IEC 60309) ? Although depending on your supplier it might fail the cheap option

author: dobsonr741
author_rank: Frequent Contributor
timestamp: January 02, 2024, 01:22:13 am
content: Philmore 61-605 and 61-625:http://www.philmore-datak.com/files/assets/common/downloads/page0074.pdf

author: langwadt
author_rank: Super Contributor
timestamp: January 02, 2024, 01:25:44 am
content: HDC-HA ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 02, 2024, 03:29:33 am
content: Any 0.156" rectangular header will do the job e.g. Molex KK or SPOX. Friction ramp holds in place. A zillion others (clones and otherwise) by every manufacturer.For easier wiring, Eurostyle pluggable terminal strips.Tim

author: ArdWar
author_rank: Frequent Contributor
timestamp: January 02, 2024, 06:21:58 am
content: Quote from: themadhippy on January 02, 2024, 01:13:44 amPlease do not use standard connector for non-standard usage. Especially when 240Vac and 16A are potentially involved.

author: Jeroen3
author_rank: Super Contributor
timestamp: January 02, 2024, 07:35:02 am
content: You can go with the usual standard round cannon connector. But wiring those is a hassle.If space constraints allow perhaps looking into Harting HAN 4 A or something similar.If you stayed in ELV range you could have used something from Neutrik, those are high quality.Or something less robust you can take locking Phoenix MSTB and put the KGG housing around it.

author: Terry Bites
author_rank: Super Contributor
timestamp: January 02, 2024, 09:08:30 am
content: Pluggable terminals. Phoenix Contact, TE, Wurth etc... Plenty of generic and knock off versions on Ali, ebay etc.They are rugged and field rewirable. I love em.
5 pin smd  voltage regulator 3.3V  - Page 1
Forum section: electronics / projects

author: ebclr
author_rank: Super Contributor
timestamp: March 24, 2017, 06:21:59 am
content: I'm looking to identify a 5 pin smd voltage regulator , from 5V to 3.3VComponent is marked SDHAny idea on what is that component ?
5 t0 12 volts problem - Page 1
Forum section: electronics / projects

author: J4e8a16n
author_rank: Regular Contributor
timestamp: February 12, 2014, 02:39:56 pm
content: Hi,I did another circuit where the the output voltage was coming out of a 555 timer #3 pin to a transistor with a relay (12 volts) working on 12 volts. It was fine.On this one how could I maintain the base voltage to 1 volt or so? When I clap with the pin 6 to the 5 volts ground. I get 3.75 volts and 30 mA.The relay is a 12 volts.

author: Paul Price
author_rank: Super Contributor
timestamp: February 12, 2014, 07:24:47 pm
content: The base voltage cannot be set higher than approx .7V with your circuit> The ON base-emitter voltage of a silicon BJT sets this limit,But why try? With your circuit as shown it would work fine with just the resistor in series with the base.

author: J4e8a16n
author_rank: Regular Contributor
timestamp: February 12, 2014, 07:44:50 pm
content: Quote from: Paul Price on February 12, 2014, 07:24:47 pmI assume you take note that the bjt is at 12volts and the TTL at 5 volts...Well why does not this work ...?Thank you for your interest.JP

author: J4e8a16n
author_rank: Regular Contributor
timestamp: February 12, 2014, 08:34:29 pm
content: It does workThis app square the input from the electret then add multiple waves in one long wave . It authaurize only one 'clap'.I am using an old electret (probably 45dB) with this application and it is not very efficient.It gives 3 volts at pin 7 .I have seen a $5 dollars electret producing 60 decibels. My problem is I have to clap at least at 2 feet for the application to work.Have any opinion on this?
5 to 15 DC/DC converter, MAX643 design - Page 1
Forum section: electronics / projects

author: tmartin13
author_rank: Newbie
timestamp: November 21, 2015, 03:49:09 pm
content: So i'm looking at designing a DC/DC converter for future projects, and they seem pretty handy to have around. I designed it in Cadsoft Eagle and I used the MAX643 switching converter. My choice for the IC comes from the fact that I could not find a library for eagle that allowed me to place the LM2577 step-up regulator that I originally wanted to use. My question is if this design will give me decent results? I'm not so much concerned with the exact output voltage so long as it is around 15volts. And in the future, is there an easy way around the limited libraries in Eagle?MAX643 Datasheet:https://datasheets.maximintegrated.com/en/ds/MAX641-MAX643.pdfReference circuit, and Eagle schematics attached.

author: pmbrunelle
author_rank: Regular Contributor
timestamp: November 21, 2015, 03:57:33 pm
content: One of the pitfalls of CAD...I like to start designs on paper/whiteboard/chalkboard, where the creativity can run amok, unconstrained by the limitations of CAD.Then, if I need to go to the computer, then I will deal with whatever CAD issues there may be. But I would never allow the CAD tool to dictate my design.Computers are supposed to help you; this seems backwards.As for EAGLE, if a part is not in the pre-installed library, you can surely draw your own custom parts.

author: tmartin13
author_rank: Newbie
timestamp: November 21, 2015, 04:14:28 pm
content: Quote from: pmbrunelle on November 21, 2015, 03:57:33 pmThat's probably going to be the approach in the future. This was mostly a quick and dirty project to show a friend it could be done. And I needed CAD to order the PCB otherwise I definitely wouldn't have messed with it.Is there any reason this circuit wouldn't perform as expected though?Here is my parts list:
5 to 3.3v level shifting with a single 2v zener and no pullup - Page 1
Forum section: electronics / projects

author: Dbuezas
author_rank: Newbie
timestamp: April 21, 2025, 11:26:31 am
content: Hi, I've never seen this done and don't understand why it won't work:Signal (0 or 5v) --- < 2v zenner --- 3.3v inputWhen the signal is low, the zenner will sink from the 3.3v to 0.7vWhen high, the zenner only passes 5-2=3v to the right side.Would that work? Why not?

author: moffy
author_rank: Super Contributor
timestamp: April 21, 2025, 11:35:08 am
content: Zeners don't make good switching devices, they have capacitance and storage times, the voltage knee especially of low voltage zeners will be quite soft, zener voltage depends on current, and you can do the same with two resistors and better linearity.

author: Zero999
author_rank: Super Contributor
timestamp: April 21, 2025, 01:44:05 pm
content: It's difficult to get zener diodes in that voltage range.Just use a potential divider.https://www.random-science-tools.com/electronics/divider.htmR1 = 33kR2 = 68k

author: Dbuezas
author_rank: Newbie
timestamp: April 21, 2025, 02:04:32 pm
content: I ended up using a 4.7k pullup and a schottky in this configuration so it can do both 5v and 3.3v in the inputBut I wondered why a single series component wasn't more used.Thanks for the answers.

author: UnijunctionTransistor
author_rank: Frequent Contributor
timestamp: April 21, 2025, 02:23:18 pm
content: Whenever you require a simple and inexpensive 2 volt drop, use a forward biased yellow or green LED.The voltage isn’t very accurate, though.

author: Dbuezas
author_rank: Newbie
timestamp: April 21, 2025, 02:34:49 pm
content: Yeah, but the trick with the zener was it has low voltage drop on the other direction

author: KE5FX
author_rank: Super Contributor
timestamp: April 21, 2025, 02:52:27 pm
content: Quote from: Zero999 on April 21, 2025, 01:44:05 pmIf you're going to use a resistor that big, you don't really need to bother with R2. The protection diodes will clamp the overvoltage at a harmless level of current.It will be pretty slow, of course. But it does satisfy the 'one part' criterion.

author: Zero999
author_rank: Super Contributor
timestamp: April 21, 2025, 04:30:19 pm
content: Quote from: KE5FX on April 21, 2025, 02:52:27 pmThat's true.The circuit can be sped up by putting capacitors across the resistors to bypass them at higher frequencies. The ratio needs to be the opposite of the resistor, so 68pF goes across R1 and 33pF across R2. If you know the input capacitance of the device and the connections, then subtract it from the capacitor across R2.
5 volt trigger step up to trigger AND gate CMOS on 14v rail. - Page 1
Forum section: electronics / projects

author: DaveHardy
author_rank: Regular Contributor
timestamp: March 10, 2013, 11:29:57 pm
content: I am looking for a really really simple way to do this. I don't have much space and would ideally like to do it with one TO-92 component and maybe 2 resistors. The only thing that I can think of is a 2n3904 and 2n3906 schmitt trigger thingy. Does anyone have a better idea?

author: Strada916
author_rank: Frequent Contributor
timestamp: March 10, 2013, 11:43:28 pm
content: Simple standard transistor buffer. BCxxx?

author: DaveHardy
author_rank: Regular Contributor
timestamp: March 10, 2013, 11:53:26 pm
content: Quote from: Strada916 on March 10, 2013, 11:43:28 pmOne transistor will reverse the phase.

author: Strada916
author_rank: Frequent Contributor
timestamp: March 11, 2013, 01:27:50 am
content: Put the input on C and put a 10k to ground. So the input is on the transitor side of the 10k then 1k E resistor done no inverted siganal. Have not tried it but should work.

author: TerminalJack505
author_rank: Super Contributor
timestamp: March 11, 2013, 01:43:52 am
content: The best that I can think of is to use so-called digital transistors (aka pre-biased transistors.) These have the resistors built-in which will save you some board space.For through-hole you'll need two of these, an NPN (for example) and a PNP (for example), and a pull-down resistor on the PNP's collector. If you go SMT then you can get the NPN and PNP in one package (for example.) You will still need a pull-down on the PNP's output.

author: David_AVD
author_rank: Super Contributor
timestamp: March 11, 2013, 02:10:19 am
content: I'm pretty sure I've seen single buffer chips with 5V in compatibility and higher (12V for example) Vdd.

author: DaveHardy
author_rank: Regular Contributor
timestamp: March 11, 2013, 02:27:59 am
content: Thanks for the responses guys.

author: Neato3000
author_rank: Newbie
timestamp: March 12, 2013, 05:44:02 am
content: I don't know if you have the space, but a 555 timer might do the trick. If you run it on the 14v rail, and then set the threshold and trigger pins to ground, you can use your 5v trigger on the reset pin of the 555 timer to get 14v on the output pin with out any other components. Except maybe a filter cap to keep the power input smooth. Then again I'm just a big fan of 555 timers, ha ha. Hope this helps!
5 Volt UPS Hack - Page 1
Forum section: electronics / projects

author: David Hess
author_rank: Super Contributor
timestamp: April 06, 2025, 10:23:01 pm
content: The other night I finally get fed up with power outages killing my internet. The only part of my network without backup power is one MOCA adapter (Ethernet over 75 ohm coaxial cable) that is in an inconvenient location.I have an old but serviceable 12 volt UPS originally intended for a modem, however the MOCA adapter is 5 volts and the 12 volt UPS needs a replacement battery. I did a search for 5 volt UPS units but did not fancy any of the options that I found. I want something which has a user replaceable standard battery and wide input voltage range.So in the meantime I soldered 4 x 10 year old alkaline D cells in series and added enough diodes to control the voltage thresholds with the original 5 volt adapter. D cells should provide about 2 days of run time. Eventually I will likely add a 5 volt regulator to my existing 12 volt UPS.

author: bdunham7
author_rank: Super Contributor
timestamp: April 06, 2025, 10:30:16 pm
content: Your scavenging and repurposing skills will be valuable in the coming post-tariff apocalypse.

author: David Hess
author_rank: Super Contributor
timestamp: April 06, 2025, 10:31:10 pm
content: Quote from: bdunham7 on April 06, 2025, 10:30:16 pmThe batteries are 10 years old. The diodes are at least 30 years old.If I extended the coaxial cable, then I could place the MOCA near my existing UPS.
50 percent off Components at Jaycar - Page 1
Forum section: electronics / projects

author: moffy
author_rank: Super Contributor
timestamp: April 24, 2023, 12:43:04 am
content: I have never seen it before but Jaycar are having a 50% off sale, for components now. Walked in to purchase 2 of everything on attached schematic (everything to the left of P1,P2), except for the TL431 which they don't stock and the LED which I have. Grand total was AUD $13.16, I almost fell over. So if you need some components and have a Jaycar nearby, now might be the time to visit.P.S. please don't try and compare Jaycar to a Mouser etc. they have never been noted for their exceptional pricing, their claim is convenience.

author: johnboxall
author_rank: Unknown
timestamp: April 27, 2023, 12:45:02 pm
content: I think the sale ended on the 25th. They were having a broad clearout.

author: moffy
author_rank: Super Contributor
timestamp: April 27, 2023, 01:11:08 pm
content: Yeah, I went in today and no discount on components,but they were having a 50% off clearance sale in the car park, but I think it was just the Campbelltown store.

author: MathWizard
author_rank: Super Contributor
timestamp: April 27, 2023, 04:30:25 pm
content: I remember getting components at Radio Shack when I was young. Now, the only electronics store I know of in a city, they don't really stock anything. They had to order a jellybean zener for me. That was a few years ago.

author: moffy
author_rank: Super Contributor
timestamp: April 27, 2023, 10:49:05 pm
content: Quote from: MathWizard on April 27, 2023, 04:30:25 pmYes it is sad how the hobbyist electronics stores are slowly disappearing, we used to have Dick Smith, Soanar(now part of Jaycar), Radio Shack and a few small stores, I think Radio House. It was also the era of the electronics magazines you bought from the news agent. Now we have the internet, information is so much more accessible but more clinical.

author: wilfred
author_rank: Super Contributor
timestamp: April 28, 2023, 01:55:19 am
content: The carpark sales in the past have been posted on their Facebook page. Which doesn't really help me much because I don't frequent facebook. I did look for this recent one at the Campbelltown store but found no mention of it. I do get an email for nationwide promotions but I don't recall getting emails for carpark sales. I presume it is because they are local activities.Clearing old stock in the lead up to end-of-tax year is not uncommon. Maybe it's time again to look at facebook each Friday to see if a store near me is having one.
50 year old dual ch ac mV meter, used mirrored film for pcb, teardown - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: April 01, 2022, 09:16:18 am
content: video link is herehttps://youtu.be/6lmpMzdiLUUContain really cool mirrored PCB's so CH1 and CH2 are exactly identical but mirrored.I found 68 written on the transformer, it looks like upside down,but it can NOT be 89 since I got this unit from my father and he know for a sure he purchased it 1970-1975one meter the coil needle bearing was loose, a little bit different tracking ch1 to ch2 depending on range,so the range/gain resistors don't track perfectly.
500KHz peak detector - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: February 26, 2020, 06:19:48 pm
content: Hi,I have to make a peak detector of up to 500KHz. Using some of the classic configurations require a more expensive (high speed high slew rate op-amps).I have come across a comparator-type peak detector below but it start introducing error at 100KHzAny other suggestions for higher frequencies up to 500KHz? Or at the absolute minimum 250KHz?Many thanks

author: graybeard
author_rank: Frequent Contributor
timestamp: February 27, 2020, 12:02:58 am
content: what is the range of signal amplitudes?do you need both positive and negative peaks?what are the source and load impedances?you need to define your requirements more completely

author: vk6zgo
author_rank: Super Contributor
timestamp: February 27, 2020, 12:23:56 am
content: An old style "peak & hold" detector can work up into UHF, but may have limitations, in that very fast peaks in the midst of a lower frequency signal may be missed.If you need to detect rarely occurring transients, you are pretty much stuck with doing it digitally, & will need a very high sample rate, plus a lot of memory.If the transients you want to see are very infrequent, maybe the device could check what it has "seen" for a set previous time, flag that as "no transient found", empty & re-use the memory.

author: Circlotron
author_rank: Super Contributor
timestamp: February 27, 2020, 12:30:45 am
content: Precision AM detector?I have a circuit at home I'll post later.

author: ricko_uk
author_rank: Super Contributor
timestamp: February 27, 2020, 02:25:35 am
content: Thank you Circlotron and Greybeard,Circlotron, look forward to it. Thank you!Greybeard,- signal amplitues as mentioned from few tens of mV to 4.5V. It depends on the configuration for every specific application. Most cases are between 1.5 and 4.5V.- the signal is as just a fixed sinewave- detection of both positive and negative but no need to differentiate (i.e. a full wave rectifier would solve that)- source and output impedances are buffered with op-amps so generally speaking at this stage no major issues there that I can think ofThank you both

author: Circlotron
author_rank: Super Contributor
timestamp: February 27, 2020, 10:06:11 am
content: Here it is.Hope it serves as a good starting point.
5050 LED Max DC Current - Page 1
Forum section: electronics / projects

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: September 15, 2020, 03:27:51 am
content: I bought some individual white 5050 LED's, not in strip form.What is the recommended maximum DC current these little guys can pass without the necessity of a heatsink.Let me tell you they are quite bright at 4mA.I soldered one of them to the 2 outside pins of a 3 pin .1" header, just do I could apply voltage to it.I think that the series resistor was 1.2KΩ at 12VDC.I will be running them at DC and not pulsed.The eBay specs were:Forward Voltage 3V-3.4V @ 20 mAAny input on operation and longevity? Please comment as I have not used them before.

author: Hideki
author_rank: Frequent Contributor
timestamp: September 15, 2020, 06:00:22 pm
content: If you have no datasheet, you have nothing else to go on except the 20 mA specified. You can of course locate a datasheet for a similar LED and hope that yours is reasonably similar.

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: September 15, 2020, 06:40:35 pm
content: Thanks that's all I have, no datasheet....I was hoping more for an answer on the heatsink or heat generated for it running say 10 hours.I can measure it, but is it a problem orThat's all you can get from a 100 pieces of bulk...
5050 Strip SMDs-Whould they be hot wide open? - Page 1
Forum section: electronics / projects

author: DW1961
author_rank: Frequent Contributor
timestamp: September 02, 2020, 08:55:09 pm
content: I just tested a 6' strip of 93 5050 SMDs for amperage and got exactly what I calculated at .21 watts per 5050 SMD when all colors are 100%: 1.6AI'm a little concerned about temperature. I didn't take a reading, but they felt very warm to the touch wide open. Does anyone know if that is normal in this situation?
50Hz power inverter for school project - Page 1
Forum section: electronics / projects

author: th3falc0n
author_rank: Newbie
timestamp: March 21, 2014, 04:43:41 pm
content: Hi EEVBlog Forum,I watch EEVblog for a long time now and never decided to register here, but now I have to work on a bigger project, so I decided to finally register.I have to (or rather want to) build a power inverter for a school paper. I decided to go with following specifications:- 12V input voltage, 200W output power- Mains controlled output (so it can be used to inject power into power net)- at least OCP/current monitoring and temperature monitoring, and of course it shouldn't power itself from mains (turn off when no input power).- stand-alone mode when not injecting power into mainsMy current plan to realize this is as following:- A seperated PCB for mains measurement with serial bus over a optocoupler to the main PCB- 25-50kHz Class D amplifier with full-bridge and a filter like described in Figure 2 in this paper (http://www.ti.com/lit/an/sloa119a/sloa119a.pdf)- Output over a 300VA 230/18V transformer.- ATmega644 as CPU, maybe with Ethernet for monitoring.I am not sure about everything yet. Especially I don't really know how to realize the Class D amp, so this post is more a call for suggestions.Some more specific questions I have are.- How can I drive the full bridge? Is there a IC for driving a Class D full-bridge at 25-50kHz?- What optocouplers are the best choice for say 9600 baud serial data?- Is a Class D combined with the transformer suitable for power injection?Thanks for any help,th3falc0n
50Hz write detector - Page 1
Forum section: electronics / projects

author: npelov
author_rank: Frequent Contributor
timestamp: April 21, 2014, 07:22:27 pm
content: Hi,I need a simple wire detector to help me avoid wires in the wall when drilling. I want to be able to detect a wire when there is load about 50-100W (220V). I don't want to know the exact strength of magnetic field or something like that - just the simplest device. What I'm thinking of is a simple LC resonant circuit, tuned to 50Hz, then 1-2 jelly bean op amps. At the end I'll put some kind ofpeak detectorwith a bleeding resistor to give me a DC signal level.So if someone has done this before, please share the experience so I don't have to invent the hot water again.After thinking a bit I realized that the neutral and live wires' magnetic field will cancel each other ... ops.Well, any tips?

author: SeanB
author_rank: Super Contributor
timestamp: April 21, 2014, 07:29:14 pm
content: Buy a stud detector, it does also detect live wires in walls, so long as they are not in steel conduit. I have one, and it does work very well tracing wiring in brick walls.The Brymen BM251 series also has an electric field detector built in. I have used it to trace the open circuit in extension cords.

author: dannyf
author_rank: Super Contributor
timestamp: April 21, 2014, 07:30:14 pm
content: -any tips? -$5 at a Home depot.

author: SeanB
author_rank: Super Contributor
timestamp: April 21, 2014, 07:34:21 pm
content: Buy one at Home Depot and post it to him then in Bulgaria. I somehow think HD has not opened there, and it likely is going to be a lot more for him to buy one.

author: npelov
author_rank: Frequent Contributor
timestamp: April 22, 2014, 12:40:44 am
content: The cheapest stud detector costs $17.58, not $5. Also I always find that the cheapest doesn't do the job. So if I buy one I'll probably search locally. If I could find one for 10 EUR I would buy. But I'm not willing to spend $50.Do home depot ship internationally? Or can I find one of these in chinese sites - DX.com or focalprice.com?
50ua to 1ma meter amp/driver schematic - Page 1
Forum section: electronics / projects

author: m3vuv
author_rank: Super Contributor
timestamp: April 10, 2020, 10:27:00 am
content: Hi all,im trying to drive a 1ma fsd meter with a cuircit meant to drive a 50ua movement,its fror diddys 5 transistor esr meter design,any ideas how this can be done?,cheers m3vuv.

author: Gyro
author_rank: Super Contributor
timestamp: April 10, 2020, 11:34:00 am
content: Quote from: m3vuv on April 10, 2020, 10:27:00 amI'm sure this question has been asked before. Err... by you!https://www.eevblog.com/forum/repair/1ma-meter-instead-of-50ua/EDIT: and simultaneously in the 5 transistor ESR meter thread:https://www.eevblog.com/forum/projects/5-transistor-esr-meter-design/msg3007512/#msg3007512

author: m3vuv
author_rank: Super Contributor
timestamp: April 10, 2020, 12:26:44 pm
content: yup sorry,i just seen that,mr diddy hadnt answered when i posted it.
50W? Really? - Page 1
Forum section: electronics / projects

author: ppTRN
author_rank: Regular Contributor
timestamp: April 14, 2024, 02:53:04 pm
content: While looking for a suitable P+N mosfets to use in an H bridge for a 12V 10A brushed motor I came across this alleged beast.https://www.lcsc.com/products/MOSFETs_381.htmlI intend to use two of these in order to complete the H bridge. But I mean... Should I trust this devices specs? 50W of power dissipation limited by the jucntion temperature of 150°C on such a small device!Do you think that is for real?

author: Ian.M
author_rank: Super Contributor
timestamp: April 14, 2024, 03:19:43 pm
content: Your link gives a product category search, not an individual device.However power MOSFET power ratings are *NEVER* for real, as they are generally specced for the entire underside of the package + the leads to be kept at 25°C, which is generally hard to do due to the high heat flux through a rather small surface area, even with an actively cooled heatsink system.

author: Siwastaja
author_rank: Super Contributor
timestamp: April 14, 2024, 03:25:02 pm
content: You can pretty much trust datasheet values but only if you know exactly what they mean. There are many catches for "young players", such as some values that apply in irrelevant conditions - but as long as those conditions are mentioned, it's technically correct information.For a 12V 10A brushed motor controller, assuming you would be aiming for something sensible like 95 to 99% efficiency, why would 50W power dissipation number matter? You would be dissipating only a few watts. In DC motor controllers nowadays, it's easier to get more silicon and reduce power dissipation, than to design heatsinking.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: April 14, 2024, 09:18:08 pm
content: Quote from: ppTRN on April 14, 2024, 02:53:04 pmYou are right it is not really 'real', it assumed you can take all the heat away.On a practical SMD pcb, low single digit watts are practical. The lower, the cooler.You should forget 'watts' and instead focus on Rds on, and get the lowest loss.Sum the P and N fet rds eg 7+13m Ohm typical of the G100C04D52 from GOFORD is 700mW in one package and 1300mW in the other.You could look at a simple top cooling heatsink, on those low profile packages, if you expect to push 10A continual.

author: bostonman
author_rank: Super Contributor
timestamp: April 15, 2024, 01:30:59 am
content: If I'm understanding your question correctly, the answer is: you're not looking for wattage in the MOSFET because it's not 10A to ground.Use the formula I^2(R), and, for a MOSFET, you might find a Rds on of 50m ohms (probably lower - I didn't search).The wattage from the MOSFET would then be 600mW if your current is 12A (I rounded up a bit from your 10A.
50w "regulated" psu, 1 NPN, 1 inductor, 1 resistor & 1 Li-ion - Page 1
Forum section: electronics / projects

author: Mp3
author_rank: Frequent Contributor
timestamp: July 22, 2021, 03:50:00 am
content: I got to thinking how could I power a 50 watt (~12A) load off a single 18650 battery(a nice one, rated for 30A CDR) with the fewest amounts of parts possible and had been inspired by an older bigclivedotcom video about an ozone generator which "misused " a transistor.This is my design. The 0.3 ohm resistor pictured is not a resistor but rather the output load for the circuit, every time the switch is closed it ramps up from 0w to 50w in ~80ms.

author: mikerj
author_rank: Super Contributor
timestamp: July 22, 2021, 06:57:03 am
content: That must be strong contender for worst schematic of the yearIt would be useful to explain what you are trying to achieve, since this circuit doesn't provide any kind of regulation, the inductor just limits dI/dt. Have you checked out the physical size and cost of a 10mH 12 amp inductor? It will be large and expensive.
51-0-51 Toroidal transformer and virtual ground - Page 1
Forum section: electronics / projects

author: ondreji
author_rank: Contributor
timestamp: April 30, 2016, 06:35:51 am
content: I salvaged this beast from audio amp. My original plan was to "upgrade" my linear PSU but then I realised that make use of 51V is quite difficult. There is an another 18-0-18 winding as well (but that would be no difference to what I have now apart from the fact that PSU will double the weight)The best idea so far is to use opa548 (5A) or lm675 (3A) to create virtual ground. I did some reasearch:http://www.goldpt.com/virtual_ground_circuit.htmlhttp://www.radiolocman.com/shem/schematics.html?di=150753http://forum.allaboutcircuits.com/threads/creating-a-virtual-power-supply-article.13678/http://forum.allaboutcircuits.com/threads/plus-and-minus-9v-from-one-9v-battery.12989/#post-79413http://tangentsoft.net/elec/vgrounds.htmlhttp://www.jamesclements.net/heres-a-rail-splitter-circuit-30v-in-15v-out-aka-virtual-ground/at the end of day it seems to be cheaper to just buy appropriately sized transformer. But then I'm not going to learn anything newAny suggestion?

author: amspire
author_rank: Super Contributor
timestamp: April 30, 2016, 07:01:55 am
content: Do you know the currents of the windings? My guess is that the 51V will be several amps at least, but the 18-0-18 could be only 1/2 an amp.For a linear power supply, it would be better to have more taps in the 51-0-51 windings unless you want to make a high voltage supply at a limited amperage - like 0-120V at 1 A.

author: ondreji
author_rank: Contributor
timestamp: April 30, 2016, 08:06:12 am
content: Amperage is not marked but I was able to get almost 400W without getting it too hot (over 30min). Based on the weight it might be between 400 - 600VA.I would say that 51-0-51 is close to 4A and 18-0-18 might be up to 2A. Multiple taps would be ideal but I haven't seen transformers like that (readily on the market).Virtual ground allows me to have up to "8A". 10A op-amps are ridiculously expensive. So far the options are:- multiple opa548 (two or three)- multiple lm675 (five?)- lt1970 + external FETs, low current PSU for LT1970, ...

author: ondreji
author_rank: Contributor
timestamp: May 12, 2016, 11:12:58 am
content: This turned out to be a great waste of time. Op-amp would need to dissipate around 80W (P = I*(Vrail - Vout) = 3A*(50-25)).This is too much even for op-amp like PA50 (100A peak, 40A, ~$850). The SOA chat for 25V difference (rail - output) allows up to 4A only.Another paperweight... (that toroidal transformer)
54-Channel Signal Generator Software for Propeller 2 (1 Hz - 25 Mhz) - Page 1
Forum section: electronics / projects

author: joabel1971
author_rank: Contributor
timestamp: July 20, 2024, 12:35:53 am
content: I wanted to share some signaling software I wrote for the Propeller 2 - and have been using for some time.I call it PWM-54. The software generates square wave signals - and uses 9 sets of 6 synchronous channels. This can easily be changed to ALL 54 channels being synchronous.If you own a Propeller 2 board - this software code is available below for testing. I wrote it in SPIN2 - and compiled it with Propeller Tool.It might be useful to your projects - especially if they involve multiple 1/4-wave divisions.The menu setup & README file are organized around my own Testbed experiments - but it still works pretty good.The software also includes a 5 layer wave-division multiplexer, and a sine-wave generator.
555 astable drift - Page 1
Forum section: electronics / projects

author: NMNeil
author_rank: Contributor
timestamp: March 23, 2017, 03:33:21 pm
content: I'm still messing around with a CDI ignition for my tractor and as part of the project have ordered a few IR2151 self oscillating half bridge drivers.While waiting for them to arrive I though I'd build the circuit as modules from discretes as a learning exercise. Put together a normal 555 astable circuit using a trimmer to get a 20KHz output, then swapped the trimmer for the closest 1% resistor. Ended up being 19.5KHz. Close enough for me.Next day the frequency has dropped to near 14KHz!. Ambient temp is much the same, so it's not that. Left the 555 running for a few hours and it had changed again by a significant amount. Swapped the ceramic cap for tantalum, changed the 555 for a different brand, but the frequency keeps shifting.Any ideas?

author: Audioguru
author_rank: Super Contributor
timestamp: March 23, 2017, 04:38:13 pm
content: You are using fake 555 ICs from ebay?Cheap resistors or capacitors from ebay?I have used American Name Brand NE555 and TLC555 ICs and their frequencies are very stable, even if the temperature changes.

author: Zero999
author_rank: Super Contributor
timestamp: March 23, 2017, 06:22:23 pm
content: Quote from: NMNeil on March 23, 2017, 03:33:21 pmThis is hardly surprising. Did the supply voltage change much by any chance?It's more likely the capacitor that's at fault than the 555 or resistors, irrespective of where you bought them from. Initially you used a ceramic capacitor which will have poor stability in the values required to make such a low frequency. Tantalum will be better but still poor. Try a polypropylene or polyester film capacitor.If stability is important, then you shouldn't be using a 555 RC oscillator. Even a microcontroller with an internal RC oscillator will give better accuracy and stability and if stability is important, you need a ceramic resonator or better still, a crystal oscillator.

author: NMNeil
author_rank: Contributor
timestamp: March 24, 2017, 02:04:23 am
content: Quote from: Audioguru on March 23, 2017, 04:38:13 pmGuilty on all counts I'm afraid

author: NMNeil
author_rank: Contributor
timestamp: March 24, 2017, 02:10:15 am
content: Quote from: Hero999 on March 23, 2017, 06:22:23 pmThe voltage was spot on 12v.As I said I just built the circuit as a learning exercise but was surprised just how much variation there was in frequency even with the dubious quality of ebay components.It does make you wonder about the logic of the knock off chip makers. They go to all the trouble of setting up a manufacturing facility, which can't be cheap, then produce substandard chips. Just as easy I'd imagine to make them of comparable quality to TI or NEC

author: wraper
author_rank: Unknown
timestamp: March 24, 2017, 02:19:10 am
content: Y5V/Z5U ceramic capacitor?
555 chip - Page 1
Forum section: electronics / projects

author: setishock
author_rank: Newbie
timestamp: September 16, 2015, 04:14:35 am
content: In the video Dave did on the 555 chip where he came up with a PWM controller for his magnifier lighting, I came up with a couple of questions. Let me back up and explain why.I have an EVGA Nvidia GTX650 video card which has an awful loud fan at higher speeds. The PWM off the card modulates the ground side of the power to the stock 2 wire fan. There is no PWM or tach leads on the stock fan. The replacement will have a 4 wire fan and I'd like to have the PWM system in the fan adjust the speed and the tach lead confirm the speed to the controller chip. OK having explained all that...1> Is it possible to replace the pot with a 10K thermistor to regulate the PWM output?2> In order to get a positive going PWM signal to the fan, which configuration in his 2 diagrams would I use?As a side note, I think the card uses a TI LM63 or LM64 chip. I can do major brain surgery on the card to modify the way the chip is wired up and make the onboard chip do like I want it. But if I can stick a thermistor to the under side of the heat sink and use an external PWM controller, it would keep me out of the OR with the card.
555 Circuit used in battery desulfator - Page 1
Forum section: electronics / projects

author: Raff
author_rank: Regular Contributor
timestamp: December 04, 2012, 05:01:09 am
content: Hi everyone,I have been experimenting with lead acid battery desulfators as I have quite a few old batteries around here that wont take a charge. I have built 2 so far for friends and another for myself, it so far has worked surprisingly well I must say.Something about the circuithas me confused. Just how does the 555 timer circuit work? Just how does the capacitor charge?It isnt like any 555 circuit Ive ever seen before. Having said that, it does eem to work.Thanks,Raff.

author: c4757p
author_rank: Super Contributor
timestamp: December 04, 2012, 05:07:52 am
content: The 555 timer is a very simple circuit with just a couple comparators and a latch. I'm sure you can figure it out if you just draw that circuit with the 555 internal circuitry in place.555 Schematic

author: Raff
author_rank: Regular Contributor
timestamp: December 04, 2012, 07:51:33 am
content: Hi c4757p,Thanks for the reply. I drew up the circuit as you suggested using the internal diagram of the good old 555, but it still doesnt makes sense to me. The cap is connected at one end to Vcc, the other end to pins 2 and 6 which are connected together and inside the 555 are inputs to op amps, which I would imagine are a high impedance. The only path to deck that I can see is via the 270k resistor, and then the internal transistor on the 555 discharge pin which is also a high impedance. Strangely the 15k resistor (which has one end to Vcc) is grounded by the discharge pin to deck as well. I just cant wrap my head around how it is supposed to work. Sorry to be a pain.regards,Raff

author: jeroen74
author_rank: Frequent Contributor
timestamp: December 04, 2012, 08:18:00 am
content: Quick analysis, could be wrongWhen the circuit starts up the voltage across C3 is zero volts. Hence, TRG and THRES are at VCC level. This ends the interval, turning on the DIS pin, connecting it to ground, slowly charging the capacitor through R4. Then TRG/THRES fall below the other level, which starts the interval, turning off the DIS pin, and it's becomes high impedance. The capacitor is thendischarged through R2.The confusion I guess arises from the fact the capacitor is referenced from VCC, not the usual GND, so all the polarities are swapped.

author: Raff
author_rank: Regular Contributor
timestamp: December 04, 2012, 08:48:50 am
content: Hi jeroen,I think youve got it there, I can see how that would work now many thanks. Its just Ive never seen a 555 wired that way before. I think the part I missed is that as the cap is initially discharged when power is applied, it appears as a short circuit placing Vcc on pins 2 and 6 and thus starting the process up so to speak.Regards,Raff