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Split Power Supply for ESR Meter

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Musicmanager

Active Member
Hi Granddad

You been in my toolbox again !
That's not my soldering iron though, that's my colonic pile popper .. .. you need to put that back where I'd like to put it !! :D

S
 

Tony Stewart

Well-Known Member
Most Helpful Member
I think the original schematic is flawed in several ways.

1) TL084 & BC557 transistor selection and slew rate problems resulting in a partial sine instead of a pulse. Slew rate is reduced such that the pulse is 22% of a sine instead of 50% of a square wave.
It should be a current source pulse such that output voltage is proportional to ESR.

Try reducing 100kHZ towards 10kHz with a larger cap. for C3 1nF-> 10nF then recapture waveforms until a better driver is found. It would be slightly better to bypass the transistor all together and drive the TL084 direct to bridge. with +4V to 0.5K load for 8mA using a bipolar signal around Virt. Gnd rather than a unipolar pulse with DC above Virtual ground.
 
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large_ghostman

Well-Known Member
Most Helpful Member
We have a cap manufacturer on the board :O, I got a dislike on my post ROFLMAO. My LCR meter gives you a choice of frequency and the results can be different from the same cap depending on frequency, but so far all the sheets I have looked at say 100kH with a couple using 10kH.
But like you say if they are out its normally way off not just a little bit.
 

AnalogKid

Well-Known Member
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Based on other circuits found while surfing, the intent might be for an intentionally slew-rate limited or R-C risetime limited square wave to approximate a sine wave. Not a great approximation for sure, but better than nuttin. Still, I vote for adding a true sine wave oscillator section. A phase-shift osc would have way lower high freq harmonics and good-enough amplitude stability without all of that Wein-ing.

ak
 
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Musicmanager

Active Member
Hi Tomizett

Thank you very much for your suggested circuit as an alternative method I could use to lose the will to live ! :D

I feel certain that if I ever were to need a circuit to oscillate my navel, this would be the one I would chose, for sure. I marvel at the notion that such a circuit would have the power to efficiently move the bulk that surrounds my navel sufficiently to cause an oscillation and feel sure if it were achieved it would be a sore wave for sure .. .. ..

Thanks again

S :D :D
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Oooh... another chance for me to plug one of my favourate circuits?
Perhaps the circuit I use here would be of use - a two transistor phase-shift oscillator with Wien-bridge style amplitude control. It gives THD around 1% is seem to remember.
Sorry, but it makes no more sense now than it did previously - a vastly overcomplicated circuit with poor performance, where's the advantage?
 

tomizett

Active Member
Point taken... I didn't mean to muddy the waters further by throwing yet another "what if?".
 

Musicmanager

Active Member
NG

I've been reading through your ESR meter posted detail .. .. can't see any problem, as you say, much more straightforward.

Are you aware there has been a revised version published in 2004 ? Some variations ... .. some of the obsolete components have been upgraded; only one battery used;

Basically, looks the same to me .. .. any comments ?

S
 

Nigel Goodwin

Super Moderator
Most Helpful Member
NG

I've been reading through your ESR meter posted detail .. .. can't see any problem, as you say, much more straightforward.

Are you aware there has been a revised version published in 2004 ? Some variations ... .. some of the obsolete components have been upgraded; only one battery used;

Basically, looks the same to me .. .. any comments ?
Never seen it :D
 

chemelec

Well-Known Member
Based on the Circuit in Post #2, Here is a PCB I Designed up.
This is Not Tested Yet, But I believe the Circuit should be good.

NOTE: THIS PCB HAS ERRORS.
 

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Musicmanager

Active Member
Hi Chemelec

Firstly, thank you for going to the trouble of producing this PCB .. .. ..
Unfortunately, at this moment in time I don't have the means to produce a custom PCB .. I tried etching once .. .. never, ever again .. I got into such a mess .. .. ... I have a small CNC machine planned and partly manufactured for the purpose, but I'm a way off completion . I have the x axis bed complete and I'm currently working on the gantry, but there's a lot of work to do yet.

Maybe some of the other members will be in a position to make use of your plan immediately .. but I will keep it in store to try out my machine in the future.

Thanks again

S
 

chemelec

Well-Known Member
Slightly Revised.

I can Produce this PCB, But shipping costs to the UK are not very Cheap.
PCB and Shipping would be 10 Pounds.

But First I Need to Build it to see if it Actually Works.
And do a Comparison of results to My SENCORE Capacitor Analyzer
 
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