ESR meter upgrades

[stj]

the mcu can push/pull 30mA, the limit is caused by the resistors.

[eccerr0r]

So far at least for capacitors that have wire leads, transistortester doing a good job for them IMHO, at least in one test it shows more information about the capacitor that I'd need multiple instruments to do.

transistortester just seems to be doing a not so good job with thyristors that can be plugged into it.

I'm also somewhat surprised it can test inductors...well, dismayed that microhenry inductors don't do so well but millihenry inductors read fine.

[stj]

the newer software and a faster crystal can improve that, or go all out and add this:

[stj]

got bored,
made a quick build for GM328's - the real ones with a monochrome display, not the black clones of an "AY-AT".

20MHz only - because you should be too.
rotary encoder helps

[eccerr0r]

More interesting things to measure.
Tried measuring a 0.047F supercap.

It reported 21.xx mF with ~9% loss and ~8Ω ESR.

Hmm... not sure what to make of this. Bad EDLC or confused meter...

[stj]

if you run it with nothing what does it say?
biggest problem i'v had with these units is leaky or shorted protection diodes

[eccerr0r]

I think the meter's fine, reports "no or unsupported device" with nothing plugged in, and remains in capacitor mode when the supercap is removed - but whether it detects supercaps correctly is the question... 9% loss is pretty huge, and 21mF vs 0.047F is about half, though I'd expect leakage to increase apparent capacitance instead of decrease.

Then using jumpers testing a 10000µF/16V, 4700µF/35V, and a 4400µF/50V standard capacitors and they came up pretty close to expected readings... just the supercap might be bad?

[stj]

i tried supercaps long ago when these things first came out and they where identified as a "cell" so it thought it was charging a battery!!
i dont know if that has improved since.

actually i think i have one - i'll report back.

[eccerr0r]

The 0.047µF supercap is rated at 5.5V. Checking its voltage when charged up, yes this thing seems to leak fast when charged to 3.6V so it may be bad, but it settles down to 3.2v and stops leaking down as quickly... Not sure what to make of it.

A capacitor of sufficient capacity may well be called a "cell"... does it actually detect batteries? Seems like a dangerous thing to hook up for the longevity of the device...

[stj]

o.k. i tried a couple of .47 at 5v ones.
dont work
both gave different readings so they could be fucked - but i dont think so.
they do have limited charge/discharge cycles though.

[eccerr0r]

I charged up this supercap to 3.6V for a couple seconds, well it indeed can light an LED with a 1K resistor for quite a while. After discharging it for several seconds through that LED (disconnected before it was flat - it was 2.4V), it was still able to light a 1W LED through a joule thief for a bit more than half a second before it went flat. So this supercap sort of works...

What kind of readings did you get?

Oh, after a charge/discharge cycle transistortester read 23mF... a bit higher but still lower than expected.

[stj]

one gave me 84uf, the other just gave a resistance!

[eccerr0r]

lol yeah that's not very good... ever tried regular capacitors that big? I haven't tried anything beyond this 0.047F yet... need to see what it does with 0.22F and 0.3F that I think I have...

---

Just tried 0.22F - it gave up, no or unsupported device.

BTW seems that having big caps inserted on power up really slows down the power on auto self-cal it seems haha.

[stj]

largest cap i have tried was 22,000 uf - it read just fine.
i doubt i'll ever find anything bigger than that.

[eccerr0r]

Start paralleling them up

hmm... need to see some others between 0.22F and 0.047F. 0.01F worked just fine too.

---

Tried 0.04F/50V capacitor - reads as 52mF 0.13Ω ESR 1.9% loss... I guess that's acceptable and within 25%...
Added a 0.015F capacitor in parallel to the 0.04F... read 71.66mF -- 31% error.
Added a 0.0165F capacitor in parallel to the 0.15F and 0.04F... read 92mF, that's a 29% error.

[eccerr0r]

Just wondering... Ever since I got this AVRTransistorTester it's pretty much stayed in my "toy" pile and have yet to actually find a bad transistor or other device that I already knew of its status of good or bad from other tools or debugging techniques... Has anyone felt the same way? Or perhaps my source of parts that need testing past basic debug techniques is low... Plus the false positives (like the thyristors that can't be triggered)...

Granted this thing does tell me a lot more of any device I stick into it than any other tool that I've used for any particular device that it supports.

Yes this sorta sounds like parade raining but just wonder how other people feel... do they use it a lot? Has it saved you effort? How so?

[jondoe]

I used mine the other day to confirm a suspicion that the mains filter caps on a device weren't performing as they should. Sure enough the test showed they were 50% of their rated value, I swapped them out, all was good after that.

[stj]

i use it a lot to check transistors for shit my multimeter diode check would miss,
like bad hfe or an internal diode

[eccerr0r]

Perhaps my issue is that I don't remove things until I'm sure something's dead... But once I find components are dead in circuit I don't need to test it again out of circuit. I guess that's why I'm not finding it as helpful as some people are.

[stj]

your not working on digital stuff then.

i recently pulled 16 transistors that powered solenoids,
didnt know the spec so just compared them to find the odd one(s) out.