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-   -   Short finder (https://www.badcaps.net/forum/showthread.php?t=107430)

vinceroger69 06-18-2022 06:30 AM

Short finder
 
Another great video looks a good bit of test equiptment too have
https://www.youtube.com/watch?v=0eixDdCpiO4

eccerr0r 06-18-2022 08:42 PM

Re: Short finder
 
Just need a voltage limited 1A CC PSU (LM317?) and you can read "ohms" (which would be milliohms) directly on your 200mV scale, if you have 20mV, even better.

Trick is not to have to send 1A through your circuit... could get toasty, but if it's a short, you probably don't really care anyway...

redwire 06-18-2022 10:39 PM

Re: Short finder
 
I think you'd need the compliance voltage-limited to say 0.2V to not damage anything. That pretty much rules out the LM317, have to use an op-amp and power transistor.
I also do well with a good bench multimeter reading uV, using lower currents. You inject a current and can follow the voltage drop to the high current short. Or use a thermal imaging camera.

vinceroger69 06-19-2022 06:48 AM

Re: Short finder
 
https://www.youtube.com/watch?v=gKaxNP24wdY

clearchris 06-25-2022 12:05 PM

Re: Short finder
 
I have been waiting for this to become available, but I admit, I'm starting to lose faith.

https://www.eevblog.com/forum/testge...with-display)/

stj 06-25-2022 07:12 PM

Re: Short finder
 
i already got the parts :(

CapLeaker 06-25-2022 07:51 PM

Re: Short finder
 
Looks like a similar idea to the Leakseeker 89, just with a display instead of a row of LEDs and sound.

clearchris 06-27-2022 10:41 PM

Re: Short finder
 
Quote:

Originally Posted by stj (Post 1144053)
i already got the parts :(

I have the parts you need to buy from ali, I don't have a few parts that need to come from mouser/digikey.

redwire 06-27-2022 11:11 PM

Re: Short finder
 
1 Attachment(s)
All that is missing is a PCB layout? It's not that complicated, it's just people wanting changes and complaining etc. that takes away all the fun.
http://kripton2035.free.fr/Projects/shorty-display.html

stj 06-28-2022 02:17 AM

Re: Short finder
 
no, we need the revised scematic with the new current-source

megaraider 06-29-2022 03:51 PM

Re: Short finder
 
No need :wink:
The current source problem arises from using the 5V output line from the Arduino Nano.
As he wrote somewhere he couldn't figure out why the voltage (5V) dropped when the tips were connected. The LM1117IMPX-5.0 max. load current is 800mA.
While that might seem to be enough it's not: one must take in account the Arduino ICs, display, DAC, Op Amp and tips current source overall power consumption!
Therefore, replace that 5V line with a reliable 5V power supply.

clearchris 07-02-2022 02:41 PM

Re: Short finder
 
Quote:

Originally Posted by redwire (Post 1144499)
All that is missing is a PCB layout? It's not that complicated, it's just people wanting changes and complaining etc. that takes away all the fun.
http://kripton2035.free.fr/Projects/shorty-display.html

Two things, the PCB layout is missing and kripton believes there's something wrong with the schematic.

So I think in the other thread people were discussing how to fix it. Also discussion of some features, true, but if you are doing a new layout, why not add some stuff if it's easy. Adding a regulator that supports battery use (not my thing, but I don't see a downside) and my personal one was upgrading the MCU. But I don't have pcb skills (yet) so I'd likely just take any board even with an arduino. But if someone with pcb design skills likes the idea of the rp2040 board, I can be point on the software...

stj 07-03-2022 02:42 AM

Re: Short finder
 
rp2040 is overkill
whats wrong with the atmega328??

i wouldnt use the arduino though, just design the chip into the new board to save space

clearchris 07-03-2022 02:20 PM

Re: Short finder
 
Maybe, maybe not. More samples per second seemed to be desirable to krypton and others. With a nano costing 3 usd and an rp2040 board costing 4 usd I don't know why anyone would use an arduino anymore for a new design. There's also a wireless pi pico board that has been released, it's pin compatible and could be an interesting option, especially if they get bluetooth working.

Designing the chip into the board is going to increase the board complexity quite a bit, and probably increase the BOM because you are buying the components separate.

redwire 07-03-2022 03:42 PM

Re: Short finder
 
Mega328's are out of stock until summer 2023 due to the semi shortages. 328P Microchip "Not Recommended for New Designs" use the 328PB but Arduino.cc is screwing up not changing over to it. Strange the Microchip 328PB webpage says 64KB FLASH but datasheets say 32KB, fired off a website typo fix msg. Too bad they didn't really give it more memory.

RP2040 nobody is using it much, so lots around and $1 for the bare IC. I have not used it. For WiFi ESP8266 does great for me.

clearchris 07-03-2022 03:55 PM

Re: Short finder
 
Quote:

Originally Posted by redwire (Post 1146194)
RP2040 nobody is using it much, so lots around and $1 for the bare IC. I have not used it. For WiFi ESP8266 does great for me.

I have seen a lot of uptake of the rp2040 among hobbyists recently. I have been on the fence about it for a while, but there seems to be a lot of momentum. The lib support seems to be there, and they aren't in short supply like some of the stm32 chips.

Has the ESP8266 firmware matured? I messed around with a few some years ago and they seemed buggy and rough. They also don't have many pins.


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