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Old 30th May 2012, 1:20 am   #21
gpateluk
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Default Re: ESR Meter Prompted By David's (G4EBT)

Hi,
I'm a complete novice to building anything electrical but have started to get very interested in fixing things. I've currently got a plasma tv to fix as a diy project. I have a multimeter but do not have anything to test capacitors. So over the past few weeks I've been researching diy ESR meters. My brain is hurting!!! The 2 that I have narrowed it down to arehttp://www.qsl.net/iz7ath/web/02_bre..._esr/index.htm and the http://kakopa.com/ESR_meter/

I like these as they have a LED to show a short.

Being a complete novice I've been looking for simple instructions, for example a list of components and an easy to follow veroboard layout or something similar.

The qsl.net design has a list but does not say what voltage the capacitors have to be. Or does that not matter in this build? I do not know. So its kinda like filling in the blanks. I guess people with experience will know straight away.

Then its trying to understand the schematic to build it.

The Kakopa version again does not have capacitor voltages. This time has a PCB design. It also has a schematic but they do not match as he writes:

"Here is the PCB design. Note that, as I said, the design is not totally finished so there are discrepancies between the schematic diagram above, the names given to components (for instance, there is no TR1) and the PCB design. For example, R20 in the PCB has been replaced by a diode and resistor in series. Once I consider the design final, I will come back and clean everything up. . . . . . maybe. "

I've contacted Kakopa if he's got a final design but I've not had a reply.

From reading this post I think I'm finally going to choose the qsl.net design! So if anyone can give me advice on the capacitor voltages that would be great!! It would be very much appreciated. Then I'll attempt my first build.

Thank you.
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Old 30th May 2012, 12:57 pm   #22
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Default Re: ESR Meter Prompted By David's (G4EBT)

As there doesn't appear to anything above 9V anywhere I would imagine that 12V would be fine. Obviously higher would be fine too, and may even be cheaper if you find them on some sort of special offer.

- Joe
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Old 8th Jun 2012, 2:39 pm   #23
gpateluk
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Default Re: ESR Meter Prompted By David's (G4EBT)

Thank you for the reply.

I've now got all my parts and have transferred the schematic to a veroboard layout on paper by hand.

You can tell I'm a complete novice as on the schematic http://www.qsl.net/iz7ath/web/02_bre..._esr/fig03.gif there are two points where there is an arrow displayed. I researched this and it says it is 'signal' or 'ground'. I don't know what to do regarding this. I've seen connections to metal parts of casings before as a 'ground' or is that 'earth'? I honestly don't know hence me asking questions.

Also there are two points it shows '+4.5V' and '-4.5V'. Does that mean if I test at these points I should get those readings?

Any help would be very much appreciated, thank you
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Old 8th Jun 2012, 7:47 pm   #24
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Default Re: ESR Meter Prompted By David's (G4EBT)

Quote:
Originally Posted by gpateluk View Post
... there are two points where there is an arrow displayed. I researched this and it says it is 'signal' or 'ground'. I don't know what to do regarding this. I've seen connections to metal parts of casings before as a 'ground' or is that 'earth'? I honestly don't know hence me asking questions.
"Ground" - American, "Earth" - British, both mean the same thing.
Really it's a chassis connection ie connected to the metal of the case if you use a metal case, it doesn't actually have to be "earthed".

Quote:
Originally Posted by gpateluk View Post
Also there are two points it shows '+4.5V' and '-4.5V'. Does that mean if I test at these points I should get those readings?
Yes, with respect to the thick black 0V line. IC1a maintains 0V midway between +4.5V and - 4.5V, and saves using two separate 4.5V batteries.
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Old 10th Jun 2012, 10:39 pm   #25
gpateluk
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Default Re: ESR Meter Prompted By David's (G4EBT)

Thanks Rob, very much appreciated
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Old 14th Oct 2012, 12:50 pm   #26
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Default Re: ESR Meter Prompted By David's (G4EBT)

I have made this ESR Meter but still not successful. Problem is that when I short probes LED lit but 100 micro ampere meter needle not moving what to do. Please help me if you make this circuit.

Mubashir
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Old 14th Oct 2012, 3:30 pm   #27
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Default Re: ESR Meter Prompted By David's (G4EBT)

Hi Mubashir,
I haven't made the circuit, but if the LED lights it could mean that the circuit is working up to IC1D, which looks to be a detector-DC amplifier to drive the meter. You could have a faulty IC, but check the components and wiring around IC1D first.
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Old 29th Oct 2013, 12:44 pm   #28
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Default Re: ESR Meter Prompted By David's (G4EBT)

Resurrecting an old thread but my meter proved its worth yet again when repairing a Venner TSA625 audio oscillator which had a couple of high ESR capacitors.
The design I found on t'interweb but with a few modifications to reduce the current drawn and optimise the amplifier frequency response. It now takes only 4mA so a 9V battery will last a very long time. I didn't fit L1 because it made little difference to the performance but more importantly I couldn't get it in the Veroboard as it was rather large.
Protection is given against connecting to charged capacitors up to 250V by virtue of the coupling capacitor C4 and diodes D2 & D3. L2 series resonates with C4 at 100kHz derived from the CMOS 555 timer to give a very low source impedance to the capacitor under test. Because the test voltage applied is so low it can be used to test capacitors in circuit without forward biassing semiconductor junctions. 100mΩ gives a usable deflection of the meter and the expanded scale is useful to measure resistors up to 50Ω or so.
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Old 30th Oct 2013, 4:45 pm   #29
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Default Re: ESR Meter Prompted By David's (G4EBT)

I use mine to measure the internal resistance of rechargeable NiCd and NiMh batteries. They should read as close to zero as possible; any reading higher than 1ohm for an AA or 2ohm for AAA and they're done for. They migh be ok for led torches and other light loads but are hopeless for digital cameras or filament bulbs.
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Old 30th Oct 2013, 9:39 pm   #30
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Default Re: ESR Meter Prompted By David's (G4EBT)

Welcome to the forum, MapperleyTop!

Very nice expanded scale on your design - only 2 Ohms centre scale. The one that I made -though an expanded scale - was 5 Ohms centre scale, so was a bit cramped at the lower end.
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Old 30th Oct 2013, 11:24 pm   #31
jimmc101
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Default Re: ESR Meter Prompted By David's (G4EBT)

Hi MapperleyTop, welcome to the forum.

Neat job, I'm pleased that it works well for you.

Talk about things coming full circle... the design you found was first published on this forum almost exactly three years ago.

Jim
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Old 31st Oct 2013, 10:23 am   #32
Philips210
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Default Re: ESR Meter Prompted By David's (G4EBT)

That's a very neat job Mapperley Top. The extended range up to 50 Ohms is an advantage for general resistance checks.

ESR meters pay for themselves in no time for locating below par electrolytics.
I built the Alan Willcox Mk2 design (Television magazine) and find it to be very good.

Thanks for posting your circuit and when time permits, I'll build this circuit and make comparisons with the A. Willcox circuit.

Regards
Symon.
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Old 31st Oct 2013, 11:55 am   #33
MapperleyTop
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Hi Jimmc101
I couldn't find the link to your circuit on my original post. Congratulations in coming up with an excellent design.
Before settling on this one I had tried many others but yours ticked all the boxes regarding sensitivity, range and protection. I simulated all the parts of the circuit, the meter driver was peaked at almost 100kHz as it should be and the scale for the meter was also derived from the simulation, the calibration points then transferred into a program called Galva (http://www.f5bu.fr/wp/?page_id=13) to draw the scale. A bit devious but it is spot on. Galva is written in French but with English instructions and is really useful for drawing scales and panels.
The layout on Veroboard needed the 'not used tracks' to be earthed to prevent the output from the 555 getting into the very sensitive meter amplifier and offsetting the zero. Now the meter does not deflect when switched on with nothing connected.
I also have one of the cheap ebay component testers which is supposed to measure ESR, at least it gives a rough idea of the ESR but is not protected in any way and will not perform in circuit measurements.
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