ESR Meter

[MickM]

Hi;
I just rebuilt my ESR meter.
I found the schematic on the web, see ORIGINAL-schematic.png for author.
This works well and is easy and almost free to build.
It is analog (which I prefer), and uses a 50uA meter.

Resistor R13 depends on your meter and pot.
The way I chose it was to set the 10K pot to mid-range.
Then uses a resistor substitutuion box to zero the meter.
This gives you a plus-minus on the zero pot.
8K2 was the closest standard value.
On my other version it was 3K3.

Yes I have a large white cat, named Gus, he likes to play with wires and push stuff onto the floor.
You may see some fur on the pcb.
We call this "Gus sign". (as in Dune's "Worm Sign").
The meter and knob are recycled.

To use you short out the leads, and zero the meter to full scale.
Then use it as an ohm meter.
I put DC blocking caps in both leads and run it off a battery.
This is for when I work on my tube gear, I can test in-circuit.

The smaller the reading, the better the cap.
It is a good idea to have some good test caps to verify your readings.

Anyway - Enjoy.

Mick M.

edit: updated to parts actually used.

[bearmos]

MickM, thanks for documenting this so well.

I think I remember seeing you reference to the original one a while back, but there's definitely enough information here to replicate this easily now. This should definitely come in handy for those pesky electrolytics on the broken SMPS i have laying around ;-) It looks like it should probably come in under $15 after all the odds and ends are purchased (analog current meter, HV caps, plus, etc), so it should pay for itself immediately since I won't be blindly replacing all the caps on the board.

[MickM]

Hi bearmos;
I don't remember posting about this before.

The reason that I rebuilt it was that my older PCB was crap.
I was just starting with Eagle and did not have a modified Laminator, just a household iron.
Also I was using an old multimeter, Radio Shack "Micronta Range Doubler 22-204C",
This was the only meter I have that had a 50uA movement.
It has a "V-A/2" slide switch

The setup was an external 9V supply, black box, external multimeter.
Quite cumbersome, but semi-portable.

I found a regular 50uA meter - Finally!!
So I just redid the layout and boxed it all up.

My meter reads from 1 to 100,, short the leads and zero.
A 10R=42, 22R = 9, 100R=2.
So it is quite sensitive.

Or you can install a good cap and zero on it, as a reference.
It puts out 0.3Vpp zero centered (+- 0.15V), at 107Khz.
This is with my junkbox values.
Its a square wave with rounded peaks, so not much harmonics.

The thing works well, and apart from the surplus meter was free.
The HV caps were the biggest that I had (250V), if you only work on 5V stuff then 25V would be more than fine.
I have a bunch of old Heathkit and Eico tube test equipment, and work on 1940s and 1950s tube radios and TV's as a hobby.
That's why I used the HV caps.
They really should be 1000V, but they are very pricey.

Mick M

[bearmos]

I don't remember posting about this before.

It was wingnut I was thinking of, looks like you were just involved in the discussion, apparently.

I found a regular 50uA meter - Finally!!
So I just redid the layout and boxed it all up.

I figured I'd just swipe one from ebay.

I'll probably be sticking with lower voltage rails and draining the caps as a precaution (I'll still throw in some 450V caps anyway). If I wind up replicating this, I'll let you know how it turns out (I always seem to contemplate more projects than I complete:)).