Morning Eric,

Well I will get on with it then Eric, seen as the postman just came and brought me a present! Thanks Eric, I don't know what time you posted but it arrived at 9.30 this morning! I think thats a record for our post.

It looks realy good too, it even has a built in battery compartment! Just goes to show they DID build things better and more user freindly back then!

Thanks again Eric..................Al

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Amongst the wretched and evil in the world. Guys like Eric prove there is still good in the world.

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Hello to all,

Well thanks to the generosity of Eric and a different ESR meter circuit provided by Nigel I have built my new ESR meter and it actually does something!

Not everything went as planned, for one thing I could not find any 470pF 1% polystyrene caps and had to substitute the ceramic ones I had. Having finally souced a 28v 24mA bulb for the circuit that the author states is 170r when cold I was a little dismayed as mine measured only 130r - I tried 2 of them as well.

Also I had to order some 1r resistors, the only ones I could find were 1w and they sadly measure 1.4r, I don't know how relevant this is?

The problem I have now is that when trying to set up the circuit as described by the author, he mentions a constant beep and all I get is a short beep no matter how I adjust the pot or preset!

I have rechecked my work and can't find anything wrong, so any suggestions from what I have mentioned above?

Eric, I decided to go with Nigels circuit as he has built one already and it also uses the full 100mA scale on the excellent meter you sent me.

I am posting a link to the meter below.

http://deathbringer2002.pwp.blueyond...y/esrmeter.pdf

Thanks...........Al

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Bear in mind your meter won't be accurate on low ranges, but it's not critical anyway, just the bottom end of an attenuator to feed a low level of 100KHz through the capacitor.

The ciruit is pretty simple, and explained in the article, do you have a scope to set the output of the oscillator to the correct value?.

I think you menat 100uA

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hi Al,

I use the SMT resistors for low ohms, in values 0.05R 0.1R for bridge test circuits, available in 1R0

If you have a scope you could check the output waveform of the Wien osc, make sure its a good sinewave.

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"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

Hi Eric & Nigel,

Yes Nigel I did mean to type uA hehehe

Good point Eric, I never thought of looking in my old board box for surface mount .5r resistors. Doh!

Anyway I do have a scope, its old and not perfect, but does work. What I can't figure out is where to put the test probe (s)

I'm also not too clear on the use of the scope as I can't find one on the net that has the same controls as mine, I think Faraday took the instructions to the grave with him for my Scopex 140-10V

Anyway thanks for all the help guys and look for the massive page of smileys when I finally get the meter working right!

PS will my ceramic substitutes be ok?

Al

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hi Al,
They are part of the Wien osc, so if you get a nice sine waveform on the output I would say OK.

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Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

Maybe you should have "Breadboarded" the project to make sure everything works before the hardwiring process on a PCB.

 

I presume he's built it on Veroboard?, the plans I sent him included such a layout.

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Hi guys,

Yes Nigel it is indeed built on Veroboard.

Al

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That might be what I need..instead of the old breadboard I made from old edge connectors

 

Hi again guys,

I still can't get any sense from the meter!

Eric suggested that I use my Scope to determine a sine wave, but I can't get a sine wave at all, that said I am unsure where to put the probes - one or both and what settings I would need on the Scope?

Any help appreciated please.

Al

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hi,
You should see a sine wave at pin1 of IC1a, at least 1Vppk I would say, also a smaller sinewave at Cx.

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Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

 

Evening Eric,

So center probe to pin 1 and outer clip to 0v (same as neg on meter) or neg on board (same as LED neg) and any clue as to where to start with settings on my old scope? I am not sure it can display a sine wave, never managed to get one to show yet


Thanks.......Al

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Yes, that's correct for connecting the scope probe. Your scope should have a calibration test point on the front usually marked with a little squarewave and labeled with the voltage it produces. Use this to check your probe. When testing your 100Khz oscillator, set the scope for 0.2V per division if using a 1:1 or 20mV if using a x10 probe. Set the horizontal sweep to 10uS per division. You may have to adjust the trigger control until the scope shows something on the display. Adjust as necessary to get a clear and stable waveform.
See this link by mechie for more detailed scope instructions:
http://www.electro-tech-online.com/e...lloscopes.html
See this link by ElectroMaster for how a scope works:
http://www.electro-tech-online.com/e...illoscope.html

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