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Old 31st Aug 2009, 6:51 pm   #1
humphrey
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Default ESR Meter advice

I want to build one. Is this one recommended? http://ludens.cl/Electron/esr/esr.html
The only part I dont understand is the transformer. Is it possible to find a scavenged pc/amp one from the resistances?
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Old 31st Aug 2009, 7:24 pm   #2
Oldtimer74
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Default Re: ESR Meter advice

I would say the answer to your question is no. However having looked at the details of the construction, as the designer says almost any ferrite core will do. The only critical thing is the number of turns which he has quoted. I have not tried it myself yet but intend to do so. If you are really stuck I could probably find you a suitable Vincor to wind it on
Pat G3IKR
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Old 31st Aug 2009, 7:44 pm   #3
Colin
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Default Re: ESR Meter advice

Hi Humphrey,

I've built this circuit and it works very well. I actually used a scavenged transformer from an old computer power supply and had no problems. In fact I tried a few and they all worked without any real difference in performance. Perhaps I was lucky, but in the end I simply used the one that was the best fit in terms of size! I also have two professionally built ESR meters and this one produces readings very much in line with the them.

The additional circuit board on the back of the meter is just a simple 'power off' timer because I tend to leave battery powered test gear on and I'm always finding the battery flat when I want to use it!

Regards
Colin
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Old 31st Aug 2009, 9:01 pm   #4
jimmc101
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Default Re: ESR Meter advice

There is an interesting point about this circuit, the mid scale reading is 5 ohm rather than the 10 ohm (=R6) that might be expected.

I believe that this is caused by the unity gain bandwidth of the TL062 being only 1MHz. This implies that gain before the diodes is about 20 at best (F = 50kHz) leading to a fair amount of non linearity and an expanded scale at the 'low ohms' end.
The meter scale provided takes this into account.

Jim
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Old 31st Aug 2009, 10:04 pm   #5
flyingtech55
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Default Re: ESR Meter advice

I built the one from 'Television' magazine. Works fine.

BTW Don't you just hate and despise people like Colin who build and finish their projects to such a high standard. Hate him, hate him, hate him...

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Old 1st Sep 2009, 11:30 am   #6
love kt3
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Default Re: ESR Meter advice

hi,i also recomend the "television" one-all the parts are standard.
as for this circuit-i think a driver xfmer from the horizantal o/p of a modern tv should do.
(but i havent tried it)
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Old 1st Sep 2009, 12:04 pm   #7
AlanBeckett
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Default Re: ESR Meter advice

Is the one from "Television" in the public domain now?
Could it be Posted?
Alan
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Old 1st Sep 2009, 6:27 pm   #8
humphrey
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Default Re: ESR Meter advice

Is it possible to dispense with the 5 volt regulator and use a 4.5 torch battery instead? (i am fairly new to this) I have a scrap Packard Bell pc monitor with some likely looking transformers.
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Old 1st Sep 2009, 7:14 pm   #9
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Default Re: ESR Meter advice

Quote:
Originally Posted by AlanBeckett View Post
Is the one from "Television" in the public domain now?
Could it be Posted?
Alan
An excellent question, does anyone know the answer? If it is in the public domain I have both the original article and the later one (with a slightly modified circuit) and could scan both.

I built one to the original article and, as others have said, it works very well.

Hugh
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Old 1st Sep 2009, 8:34 pm   #10
Hermit6345
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Default Re: ESR Meter advice

Quote:
Originally Posted by humphrey View Post
...
The only part I dont understand is the transformer. Is it possible to find a scavenged pc/amp one from the resistances?
I built this unit and used a Mullard Vinkor LA4346. It took but a few minutes to wind on the required number of turns By hand. I used about 36 SWG I think. I have a spare Vinkor, former and clips if you want one. Just PM me.

Ian
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Old 2nd Sep 2009, 8:14 am   #11
Kat Manton
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Default Re: ESR Meter advice

Hi,

Quote:
Originally Posted by humphrey View Post
The only part I dont understand is the transformer. Is it possible to find a scavenged pc/amp one from the resistances?
Nobody's picked up on, "... from the resistances"; I think you might've misunderstood the diagram.

The resistances aren't given. The numbers '400' and '20' on the diagram are the number of turns of wire on primary and secondary respectively.

So it's easy enough to make. 400 turns is within the limits of my patience, anyway. Much more than that and I start thinking about coil winders...

It appears that salvaged ferrite cores from old PSUs etc. are likely to work too. What you wind the transformer on doesn't seem too critical.

I think I'll be building one myself fairly soon; I think I can do it without buying anything

Cheers, Kat
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Old 2nd Sep 2009, 1:35 pm   #12
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Default Re: ESR Meter advice

If you want to avoid coil winding have a look at this: http://www.members.shaw.ca/swstuff/esrmeter.html I've been using this design for few years.
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Old 12th Sep 2009, 11:39 am   #13
humphrey
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Default Re: ESR Meter advice

I made it on veroboard and a small transformer from an old PB monitor. The meter is from an old £4.99 multimeter and it worked fine first time. Now to make a case for it.
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