Ho' made ESR meter

[Digital Technophile]

I've found the need to have a ESR meter as I get more and more into electronics repair. I first looked at some home brewed designs, but didn't feel as though I could pull something like that off. Then I found this meter, but the price tag is out of the budget ATM. So I decided to revisit the idea of building a meter from several designs out on the 'net.

Accidentally hijacked this thread, my apologies to the OP! So I wanted to, for the sake of some decorum on this site, I'm beginning this thread to continue with the discussion. Th3_uN1Qu3 has been working on a design here, that you've modified to utilize your PIC controller and some special mods, right?

@Th3_uN1Qu3, that digi-pot is nice, and I have a sneaking suspicion you'll be using your PIC16F876A to control it! Two things come to mind regarding it. First, a manual pot is "infinitely" adjustable and this has steps. So 257 steps/5k ohms give you 19.4 ohm adjustments? Second once you've calibrated the unit, theoretically you shouldn't need to readjust it again yeah?

[Longbow]

Re: Ho' made ESR meter

Hi DT,
There are a number of schematics on the web for home-built ESR meters, that vary in complexity and usefulness. If you want to build a project, especially one with a pic programmer, it would be only as a learning experience. The final cost (not counting your time) will be far more than the Blue ESR meter, which is an excellent design at a reasonable price. Everyone on the badcaps forum should have some type of ESR meter - this should be obvious.

Essentially, an ESR meter generates an AC signal, and measures the AC resistance of an electrolytic capacitor. Exact readings are not needed, just a little experience with your particular meter. As far as needing an electronic potentiometer, I doubt that it is necessary. One helpful feature of most modern uPC's is that they will read external adjustment values once during power-up. That way, variations in the resistance value, contact noise, etc. will be ignored. This feature is easily programmed into a PIC as well. Good Luck.

[Agent24]

Re: Ho' made ESR meter

Bob's Blue ESR meter is worth it, cheap, easy to build and very easy to use. I think it also makes a good test of skill. If you can't solder it together properly you have no hope of doing well on a motherboard (unless you practice, of course!)

There are several designs also here: http://kripton2035.free.fr/esr-repository.html all of which seem pretty nice. Some also measure capacitance which is a nice bonus.

They shouldn't be too expensive, if you shop around for some of the parts. I doubt any would cost more than the Blue ESR meter, especially if you made the PCB yourself.

[Th3_uN1Qu3]

Re: Ho' made ESR meter

@Th3_uN1Qu3, that digi-pot is nice, and I have a sneaking suspicion you'll be using your PIC16F876A to control it! Two things come to mind regarding it. First, a manual pot is "infinitely" adjustable and this has steps. So 257 steps/5k ohms give you 19.4 ohm adjustments?

O'course... but i'm not gonna use it for calibration. I'm gonna use it for a far more, um... entertaining purpose.

[Digital Technophile]

Re: Ho' made ESR meter

Thank you all for your replies!

ATM, I'm finding myself choosing between buying a prefab (of which I'm leaning toward a Peak Atlas ESR60), a ready to assemble (of the offerings I've looked at, Bob's seems to be the nicest, well thought out, and complete), and stumbling through various schematics on the interwebs to assemble my own (probably the least likely right now considering my level of confidence with my electronic engineering skills).

I just found this book which I so far would recommend to anyone like myself wanting to go further into the art of electronics (it is an art isn't it?). Even for experienced tech's/engineers, IMHO is a pretty comprehensive read from passives, discretes, big ol' chapter on op amps, theory to real world application, ANNNND>>> PIC controllers!!!

Finding time to read this book is the real challenge; after looking for work like I've never looked for work before, trying like mad to start a new career, I get a call yesterday from GE Aviation wanting to know if I'd like to come in for an interview (hmmm, I'm more of a fan of George Westinghouse/Nikola Tesla and really never liked Tom Edison, but like Fairchild Semiconductor are just namesakes from the past...think I'll get over it ). The position is for a machinist of which I've been for over 14 years, but the funny thing is that I applied like over 6 weeks ago, so the call completely took me by surprise!

But back to the main point of the whole thread, I'd like to focus on the theory and construction of the circuitry involved with an ESR meter. Like Th3_uN1Qu3 already knows, the heart of an ESR meter is a PIC micro-controller.

@Longbow: I certainly realise the fact that what I'd like to undertake WILL cost more than just buying one indeed. But for me it's really a learning experience, which is why I'll probably end up buying a Peak for my immediate needs. The PIC programmer is what's going to hit my wallet the hardest, hence why I'd like to plan this out as best as I can before purchasing one.

@Agent24: Bob's meter is indeed a nice one for a kit and like I stated before the one I've been leaning toward. I'm confident in my soldering skills, even after a decade long "hiatus", getting back into it was like a proverbial bicycle ride! I finally stopped using my roommate's POS iron and bought a cheap but nice Weller 25 watt'er with three tips and some other little goodies for $18. And thanks for the link, there are some very compelling designs there that I'm looking into. I also like this one as well (thanks TheLaw!)

Gotta go for now, I'm posting another thread, then I have to get to work on the rear subframe bushings on my car *hears bull whip cracking*.

TTFN
Brian