Author Topic: 5 Transistor ESR Meter Design  (Read 170023 times)

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Online bd139

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Re: 5 Transistor ESR Meter Design
« Reply #225 on: May 01, 2019, 10:00:27 pm »
Good luck. Any problems, post back  :-+
 

Offline picofarad

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Re: 5 Transistor ESR Meter Design
« Reply #226 on: June 01, 2019, 09:52:50 am »
So, finally, the last components arrived (the diodes) and I've completed the build. Initially, it didn't work just right. After some troubleshooting that led to discovering an error in my pcb layout (basically, the collector of Q3 was shorted to ground), it worked perfectly. It's incredible sensitive. I'm gonna to test different probing cables since I've found that using regular alligator clip cables (those kits with 10 jumpers from ebay) it's impossible to zero the meter due to the cable resistence.

Anyway, great instrument! Now it's time for the boring part: the enclosure building. :palm:
 

Offline Richard9026

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Re: 5 Transistor ESR Meter Design
« Reply #227 on: June 02, 2019, 01:15:15 pm »
Hi!
I made the circuit, everything is working fine (all DC voltages match + 89,5khz oscillator frequency) but I need a higher current to drive the 250uA VU meter that I got. Without any resistance in series with the meter (no R23 and R24) I get 160uA with the probes shorted.
What do I need to modify to increase the current output? Without affecting the scale deflexion.
« Last Edit: June 02, 2019, 01:18:12 pm by Richard9026 »
 

Offline Jay_Diddy_B

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Re: 5 Transistor ESR Meter Design
« Reply #228 on: June 03, 2019, 01:45:37 am »
Richard and the group,

If you want to experiment with the circuit, you can try this modification:



It works in LTspice, you will have to play with the meter circuit. Start with a 4.7K pot in series with the meter.

This modification increases the current consumption to about 22mA. Not a problem if you use the ESR meter occasionally.

Let us know if this works.

Regards,

Jay_Diddy_B
 
The following users thanked this post: Bryan, Cliff Matthews, Richard9026

Offline Richard9026

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Re: 5 Transistor ESR Meter Design
« Reply #229 on: June 04, 2019, 05:54:55 am »
 Yes, this circuit modification works just right! Now I can peak my M68501 250uA vu meter!
I will post a detailed analysis and measurements later.
 

Offline Richard9026

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Re: 5 Transistor ESR Meter Design
« Reply #230 on: June 04, 2019, 10:02:30 pm »
For the modified circuit:

Measurements are taken with the M2038 voltammeter, on the 0,75mA / x1 range (that means 750uA full scale). The scale is marked 0-150, so multiply by 5 to obtain the uA value.



Its internal resistance, measured on this range (0,75ma x1) with a multimeter is 21,7ohms

Connecting the meter to the circuit (no pot/resistor in series) and shorting the probes, I get a reading of exactly 70, multiplying by 5 -> 350uA

Measuring the voltage on the terminals of the voltammeter: 0,007V

The ESR deflection on the linear scale of the voltammeter is the same as yours:

Your meter deflection (taken from page 1):



Notice that the 2 ohm inscription is on the left side of the middle line.

The voltammeter deflection is the same as above, if I connect a 2 ohm load across the probes of the circuit, it shows 32 -> 160 uA, that's right below 175uA (half of 350uA).

But I got issues when I use a VU meter.

I don't think that the circuit is the problem, because when connecting the voltammeter, that has a linear scale, the deflection is the same as yours.

The VU meters:



They both have the same "problem".
 
I don't think it's a problem, maybe is something that vu meters do, and maybe you guys know:

So, I connected the meter circuit as below:



With the help of the 250k pot, I can adjust/peak the needle of the VU meter, and the voltammeter offers a precise reading of the current passing thru the VU meter.

So I peaked the VU meter (capacitor probes shorted):



I get a reading of 57,5 -> 287,5uA, let s call this the full deflection point.

Logically, the mid point will be at 57,5/2= 28,75 -> 143,7uA

I adjusted the pot so I can get the needle right in the middle:




BUT I get a reading of 22 -> 110uA.

This means that the mid point is shifted 33uA below what it should be (110ua instead of 143ua) and the delflection on the VU meter would look like this:



The left side (the higher ESR values) have more space on the scale than the ones on the right side (the lower ESR values). This makes the reading of low ESR values harder, that is a little of a problem.

At the beginning, I mentioned that a 2 ohm reading will be at the left side of the scale.
If I connect a 2 ohm resistance at the capacitor probes:



See, the needle is in the right side of the scale...

Why is it so? Are the VU meters not linear?  I get the exact same problem with the black grundig vu meter, the mid point is not at the half of the full curent deflection.

Thanks!
« Last Edit: June 04, 2019, 10:04:50 pm by Richard9026 »
 

Offline cpt.armadillo

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Re: 5 Transistor ESR Meter Design
« Reply #231 on: June 05, 2019, 09:18:25 pm »
From https://en.wikipedia.org/wiki/VU_meter, it looks like it is not going to act linearly like a simple ammeter or voltmeter. I won't pretend to understand it but audio stuff often ends up using dB scales.
 

Offline Jay_Diddy_B

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Re: 5 Transistor ESR Meter Design
« Reply #232 on: June 06, 2019, 02:12:44 am »

snip ...

Why is it so? Are the VU meters not linear?  I get the exact same problem with the black grundig vu meter, the mid point is not at the half of the full curent deflection.

Thanks!

I am not sure about the VU Meters. They are certainly not precision instruments.

It is possible that they are non-linear.

You will have to make a custom scale.

Have a look at this message:

https://www.eevblog.com/forum/projects/5-transistor-esr-meter-design/msg172109/#msg172109

Regards,
Jay_Diddy_B
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #233 on: June 19, 2019, 12:04:11 pm »
are these mirrored,well except the silkscreen.
 

Offline kkamel

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Re: 5 Transistor ESR Meter Design
« Reply #234 on: July 15, 2019, 07:12:38 am »
Hi Jay_Diddy_B,
Thanks for your excellent work and thanks for sharing it with us.
I did prepare all the components except of course 1N5711, can’t find it at all can I use BAT85 I can scavenge them from an old board?
I have the Multi-Function Tester - TC1 but I need to make in-circuit testing.
Thanks again,
« Last Edit: July 15, 2019, 07:17:24 am by kkamel »
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #235 on: August 12, 2019, 12:23:48 am »
seems very odd to me, how so many have supposedly built this and had it work before the routing mistake was spotted!!!!
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #236 on: August 12, 2019, 04:51:10 pm »
hi all,ive built this but have no meter movement,any ideas?,would send some scope pics but cant a my scope just died!,its oscillating at 80khz ,so that parts ok,the meter movement checks out ok,ive took some pic of variouse voltages,hope they display ok,find attached,any pointers on what wrong?,cheers paul.
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #237 on: August 12, 2019, 04:52:47 pm »
meant to say in my last post the readings were with the test points open.
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #238 on: August 14, 2019, 09:35:14 am »
anyone help ?
 

Offline Cliff Matthews

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Re: 5 Transistor ESR Meter Design
« Reply #239 on: August 16, 2019, 01:56:15 pm »
anyone help ?
You've posted on the forum 173 times, you should know jpg files can be uploaded..  |O

If by chance, you didn't have a free image program like IrfanView, I'll post the the useful one.
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #240 on: August 17, 2019, 03:03:26 pm »
thanks for that,i didnt know about the files,ive attached the pic of my various readings,anyone have any idea why its not working?,ps the movement is new and working.
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #241 on: August 19, 2019, 05:57:32 pm »
well ive solved one problem and i have another,when building this i put a linkin place of the 10k pot as ive got mine on the front panel,i had forgot to solder one side of the link,anyway i soldered it,not the meter is hard over to the right with test points open,the only way i can get the meter to read at zero ie left,is by removing c8 22nf,ive checked all the cap values etc,for  c4+c6 im using 100uf electrolytics,any ideas?,cheers m3vuv.
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #242 on: August 20, 2019, 12:57:33 pm »
well it looks like ive found the issue,ive been building this using the design for the pcb from mauroh,in short its a total fuck up,ive traced it thru after building it,the leg of c3 that should go to q4 base,his goes to q5 base and c8 is going to the base of q4 not q5,why to ppl not build there desigh of a pcb before releasing it?,ffs what a fuck up!,lost count of the hours ive spent on this fuck up and wasted copper clad,the cuircuit works well as i built it manhatan style a while ago,just maurohs routing is a
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #243 on: August 20, 2019, 12:59:32 pm »
well it looks like ive found the issue,ive been building this using the design for the pcb from mauroh,in short its a total fuck up,ive traced it thru after building it,the leg of c3 that should go to q4 base,his goes to q5 base and c8 is going to the base of q4 not q5,why to ppl not build there desigh of a pcb before releasing it?,ffs what a fuck up!,lost count of the hours ive spent on this fuck up and wasted copper clad,the cuircuit works well as i built it manhatan style a while ago,just maurohs routing is a fuck up even 2nd time around!
 

Online bd139

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Re: 5 Transistor ESR Meter Design
« Reply #244 on: August 20, 2019, 01:05:25 pm »
Joy. At least you got to the bottom of it. Perhaps there should be a warning in this thread.
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #245 on: August 20, 2019, 02:29:59 pm »
makes me laugh at the amount of ppl have built this and supposidly had it work,ive had various attempts at building this over the last few years,it was only today i figured it out,i made it on thin pcb so holding it up to the window could see thr to where the tracks went,supprising its not been spotted before,im just etching jdiddys original,we will see how that fairs!
 

Online bd139

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Re: 5 Transistor ESR Meter Design
« Reply #246 on: August 20, 2019, 02:36:50 pm »
This used to be a design feature in some of the old electronics magazines I read when I was a kid :-DD

Think mine only worked because I did it from the schematic rather than the PCB layouts.
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #247 on: August 20, 2019, 04:24:05 pm »
thats the same as my first one was made manhattan style from the schematic.
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #248 on: August 20, 2019, 09:57:56 pm »
Well p diddys pcb worked like a charm strait off,ppl need warning about mauros pcb layout,its plain wrong,cant ever work,wish i had never of seen it with all the time and money wasted!!
 

Offline mauroh

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Re: 5 Transistor ESR Meter Design
« Reply #249 on: August 22, 2019, 01:41:28 am »
Dear m3vuv,
    I apologize for the trouble I caused to you and to someone else that used my incorrect files....
Just to understand what happened and to fix further mistakes, can you please tell me which version of my PCB Layout have you used?
The 1.3 that is the latest one should be correct.
There was a trace overlap in the previous versions that was spotted by another forum member on February 2019, see this: https://www.eevblog.com/forum/projects/5-transistor-esr-meter-design/msg2213103/#msg2213103
Please let me know if you have found another issue.
When I uploaded the corrected files, I delated all the previous one from all my posts in this thread and now I'm sure all the files are updated.
Please let me know
Mauro

If you use mauroh PCB Layout, do not use files with version below 1.3. There was a mistake in the routing.


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