Well, if you used the PCB layout, then your LM339 should be OK because the power pins are opposite that of the schematic.
Here is a good site for datasheets:
Datasheets.org.uk :: Datasheets :: Datablad :: Datenblatt :: Fiche technique

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On further analysis of the circuit, I doubt that the circuit never works as the osc2 pin is loaded with 0.1uF cap to rectify the clock. Instead, they might have buffered the clock with a FET and then processed it's output.

For On/Off using push switches, I feel that one need not depend on the clock as a signal.

Another observation-- the 2 red LEDs used on base- emitter junctions of PNP transistors, driven by 3.3 and 33k are doubtful for lighting up at 5V supply. the one with 33K is definitely wrong.

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Sarma.

 

Thanks for the replies guys,

I have been trying to get some sense out of this circuit for weeks now! I originally built the circuit from the authors pcb layout but there were too many discrepancies to ever get it to work!

Then perhaps foolishly I built the circuit from the schematic onto veroboard, not realising that the LM339 was connected reversed polarity, so I may have killed that now!

I just wish I could find another ESR meter circuit and then I could start afresh as I am fast running out of patience and parts.

If anyone knows if a 339 can survive reverse polarity or knows of a different ESR circuit I would be very grateful.

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

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hi Al,
It looks as though that project was an engineering students assignment.

There is no guarantee that it did or will ever work, I cant be sure how far the project was proven.
The software displays labels, but beyond that...

The LM339 is about 40 pence to replace.

Regards

__________________
Eric
"Good enough is Perfect"

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

 

Have you Googled "ESR meter schematic"? I've been wondering why you are beating your head against the wall on this one.

__________________
Ron

 

Hi Eric and Ron,

Yes Eric, the 339s are cheap enough but it means either a longish trip to the nearest shop, or waiting till I have more stuff to order so I can get free postage!

Ron, as for Googling for another meter, I seem to have just about worn out my mouse, most links seem to be selling them, Peak for instance (which are great meters - I have their transistor/diode meter - present from the wife at Xmas!

As to designs for one, that is more difficult, some seem to be 8051 based which I can't do, and other links just lead to someone saying they made one but often have no schematics/diagrams.

I may have to wait for Xmas and put a few subtle hints to the wife, but I hate to be defeated by things, its not like I'm all that successful at much else to make up for it! hehehe

Regards............Al

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Al, here are some schematics I found with Google. I have no idea if they work. You may have already seen some or all of them.

Equivalent Series Resistance Meter

Esr tester for capacitor

ftp://ftp.eskimo.com/u/m/mzenier/esrmeter.gif

99 Cent ESR Test Adapter

Silicon Chip Online - Circuit Notebook

http://members.shaw.ca/swstuff/esrschematic.png

ePanorama.net

ePanorama.net

ePanorama.net

__________________
Ron

 

Hi Guys,

At long last after nearly a month of debugging this circuit I have it running, b ut with a small problem, however much I adjust the 4k7 trim pot I cannot get a correct capacitance reading! EG a 470uF cap reads 4.7uF.

Can anyone tell me the part of the circuit that is likely to be the cause of this problem. I have checked and rechecked the resistor values and they all seem ok, so do the transistors.

If anyone can help please feel free to suggest anything that may be wrong or any errors in the circuit.

Eric, when you had the simulation running did the values of the test cap and reading tally up?

Thanks for looking guys.................Al

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hi Al,
On simulation it isnt possible to calculate/measure real values.

I have project board on the shelf set up with a 16F628A and 3.2768Mhz xtal.
I'll knock up the 'cap test' osc logic and give it a try, get back to you.

The 470uF cap, did you try it both ways around, [its a polarised electrolytic], on the test probes.

What reading do you get for say 0.47uF ceramic.?

__________________
Eric
"Good enough is Perfect"

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

 

Thanks Eric,

Yes I tried both ways and same result! Strange

As for 470n nearest I could lay hand on easily was a 1.8uF polyester and that shows 0.00000000.

I have a feeling something is either way too small or way too big mate, but don't know what.

BTW As you suggested I have dispensed with the front end of the circuit and now am running from a 7805 instead of all the gubbins the author used. Also no backlight required or credits, so also dispensed with.

Good of you to test for me mate, thanks............Al

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hi Al,

Looking thru my 'AlsStuff' folder, which circuit are you referring too.

Is the LCF or the ESR meter.

If its the LCF I can do that fairly quickly, but if its the ESR I have doubts about that circuit/program ever being able to measure a capacitors ESR.!!!

__________________
Eric
"Good enough is Perfect"

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

 

Hi Eric,

Its the ESR circuit, the one at the first thread in this post mate.

Regards Al

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OMG.
I thought you had consigned that to the recycle bin.

I still believe that the ESR project was a students assignment and most likely never worked.

There are so many errors/omissions on the circuit diagram, I suspect the program could be the same.
The results you have posted for the test capacitors, ie 470uF and the 1u8F caps suggest the program
and method of measurement is unproven.

 

Hello again Eric,

I would have as you said have binned the project but alas its the only one I could find on the entire web which didn't require an micro amp analogue meter, and the only meter I have is a 50 milliamp one.

Seeing as I had all the bits for it I thought I would plod on with it, and indeed after only a month of trying I got a reading! I admit its the wrong one but I was so happy to get anything that I was spurred to carry on.

I do really need an ESR meter mate, some caps I tested with the cap meter later decided to set alight, even though they tested perfect on capacitance, and a major fire was only averted because my mate was there at the time and turned off his power quickly!

So I need to get something working to avoid that happening again! I don't feel I could trust a cap again without checking its ESR, I wouldn't be able to sleep knowing that I could have caused someone to be incinerated.

Anyway Eric, any suggestions or help would be much appreciated and I will live in hope of getting a circuit for ESR working eventually.

Regards..............Al

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Buy the Peak Electric one, you even live fairly close to where they are made (Buxton), it's so much better than the home made ones (I have both).

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