Author Topic: 5 Transistor ESR Meter Design  (Read 164425 times)

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Offline Jay_Diddy_B

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Re: 5 Transistor ESR Meter Design
« Reply #200 on: November 22, 2018, 03:07:15 pm »
Hi everybody,
I also trying to build this esr meter myself but something goes wrong.
Im using the Mauro's layout for the breadboard.All the components are the correct ones except the two 2.2 uf caps which i 've used electrolytics.
The thing is that i do get the right voltages up to Q3 but after the Q3 somethings goes wrong.
My meter says 1.9v on the Q4 collector and 1.4v on the collector of Q5.These ara way lower compare to the values that Jay Diddy posted.

Also in the R24 possition should i use 12k as you guys or should i use  this formula: 1800 ohm(50uAmeter) + 10k/2(pot) -7500ohms=700ohm?
If anyone can help it would be great!

Mikeva,



What voltage do you measure on the bases of the transistors?

The base voltage should be 1.3V

This means the emitter voltage = 1.3 - Vbe = 0.65V

Ie = 0.65V /Re = 2mA

Ic is Ie - Ib, Ib is small so Ic = Ie

Vcollector = Vsupply - Ic x Rc = 5V - (2mA x 1.2k  \$\Omega\$) = 5 - 2.4V = 2.6V

Check the supply voltage is 5V.

Check the values of the 330 \$\Omega\$ and 1.2k \$\Omega\$ resistors.

Check the transistor connections.


Regards,

Jay_Diddy_B
 

Offline Mikeva

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Re: 5 Transistor ESR Meter Design
« Reply #201 on: November 22, 2018, 03:36:39 pm »
Hi Jay!

So at the momment i'doublechecking my conections and so far seems ok.
Regarding the voltages  i measure:
Q4
collector=1.55
base=1.9
emitter=1.19

Q5
collector=1.9
base=1.26
emitter=0.58

from the regulator  i measure 4.98v with fresh battery.
checked all resistors-ok


Thanks for your reply Jay.
And thanks for the nice work you did about the meter!
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #202 on: December 09, 2018, 08:19:13 pm »
well i gave up on building the pcb version of this,i made it manhatan style,the only issue i have is with the test leads shorted i adjust it to fsd,then with nothing conected to the test leads the meter sits at about 30% of full scale,als all the esr calibration readings are only about 50% of what they should be,ie 2 ohms reads 1,10 ohm reads about 2.5,any ideas?,the diodes i used were some old oa series i had kicking about,would bat 85 diodes be better,im assuming the screwy readingd are down to diodes being non linearcant fathom why it sits a third way up the scale tho with nothing conected!,cheers m3vuv.
 

Offline Jay_Diddy_B

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Re: 5 Transistor ESR Meter Design
« Reply #203 on: December 10, 2018, 04:23:58 pm »
well i gave up on building the pcb version of this,i made it manhatan style,the only issue i have is with the test leads shorted i adjust it to fsd,then with nothing conected to the test leads the meter sits at about 30% of full scale,als all the esr calibration readings are only about 50% of what they should be,ie 2 ohms reads 1,10 ohm reads about 2.5,any ideas?,the diodes i used were some old oa series i had kicking about,would bat 85 diodes be better,im assuming the screwy readingd are down to diodes being non linearcant fathom why it sits a third way up the scale tho with nothing conected!,cheers m3vuv.

I am sorry to hear that you have are trouble getting the circuit to work.

I would suggest that you start by measuring the voltages at the various place in the circuit. The values are shown in the schematic in reply 204 of this thread.

Do you have access to an oscilloscope and a camera? can you post pictures of the waveforms?

I would also suggest looking at this video produced by W2AEW



Let us know what you find.

Regards,
Jay_Diddy_B
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #204 on: December 11, 2018, 02:20:02 am »
dont get me wrong,it does work quite well,its just the meter sitting a third way off the bottom makes it awkward as the max esr tops out at about 10 ohm,ive redrawn the scale to match,i did check voltages,if i remember q5 collector was at about 2.9 volts,wondered if it was the diodes,if i decreased r21  slightly do you think it would help?,cheers m3vuv.
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #205 on: December 11, 2018, 04:09:28 pm »
well,ive fitted mullard oa47 diodes inn place of d3 and d4,its made no difference(the needle still sits at 20% deflection with input open,ive checked all resistor values,(they seem spot on ( all 5% tolerance),the voltage readings i get are as follows ,left to right,originals first,mine in brackets. 4.98(4.990) 4.56 (4.533) 2.42 (2.748)   1.29 (1.286)  2.80 (2.81)  2.78 (2.652)  1.29  (1.295),i will post some screenshots from the scope later,ok.,im pulling my hair out now!! lol,73 m3vuv.
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #206 on: December 11, 2018, 06:46:04 pm »
heres some scope shots,taken at the voltage test points,left to right on schematic.,may have tio upload them over a few posts due to file sizes!
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #207 on: December 11, 2018, 06:48:30 pm »
and againe
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #208 on: December 11, 2018, 06:50:42 pm »
and againe
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #209 on: December 12, 2018, 01:45:27 am »
disregard the last pic heres q5 collector.its at .5v/divand .1ms/ div.
 

Offline Jay_Diddy_B

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Re: 5 Transistor ESR Meter Design
« Reply #210 on: December 12, 2018, 10:42:00 am »
well,ive fitted mullard oa47 diodes inn place of d3 and d4,its made no difference(the needle still sits at 20% deflection with input open,ive checked all resistor values,(they seem spot on ( all 5% tolerance),the voltage readings i get are as follows ,left to right,originals first,mine in brackets. 4.98(4.990) 4.56 (4.533) 2.42 (2.748)   1.29 (1.286)  2.80 (2.81)  2.78 (2.652)  1.29  (1.295),i will post some screenshots from the scope later,ok.,im pulling my hair out now!! lol,73 m3vuv.

M3VUV,

The DC voltages at the various points are correct. This means that all the parts that determine the DC voltages are correct.

The parts with the blue check marks are correct.



The circuitry in the emitter of the transistors, the 33 \$\Omega\$ resistors and the 2.2uF capacitors impacts the AC gain of these amplifier stages.

These 2.2uF capacitors have been discussed before. I used ceramic capacitors in the prototype. Other people have used low ESR electrolytic capacitors. If you use electrolytic capacitors you can increase the value to get a lower ESR. If the ESR is too high it will reduce the gain of these amplifier stages. Try 47uF or 100uF 105C low ESR electrolytic capacitors.

Operating Frequency

You say that the Tektronix 453 scope is set to 0.1ms/div. The UNCAL lights are on for the timebase and the vertical inputs:



The variable timebase slows the time/div by up to 2.5 times. So if the UNCAL light is on the timebase is between 0.1 and 0.25ms/div



To extinguish the UNCAL lights, turn the red knobs on the vertical controls clockwise. There is normally a click, a switch, and the lights will go off. Do the same with the red knob on the timebase.

x10 Horizontal Magnification

The Tektronix 453 has a Horizontal magnifier. This should be set to off and the MAG light should be off:



Make sure that the Horizontal Mag is set to off.

If I assume that the timebase is 0.1ms/div, the period of the waveform shown is about 1.5 div or 0.15ms
This means the frequency is only 6kHz and 10 times lower than it should be. Check the value of C2 in the oscillator section. It should be 1.5nF, 1500pF.

Regards,

Jay_Diddy_B

« Last Edit: December 12, 2018, 10:47:59 am by Jay_Diddy_B »
 

Offline Jay_Diddy_B

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Re: 5 Transistor ESR Meter Design
« Reply #211 on: December 12, 2018, 11:12:36 am »
Hi M3VUV,

I have looked at this some more. This waveform is wrong:



I modified my LTspice model so I could look at possible faults that would cause this:



If the base capacitor, C3 in the LTspice model, is 1nF instead of 10nF it will cause the same waveform. The current through R22 is the same as meter deflection.

If C3 (LTspice designation) is the correct value, 10nF there is no meter deflection.




If C3 is too low there will be meter deflection.




Check or replace this capacitor on your hardware.


Regards,

Jay_Diddy_B
« Last Edit: December 12, 2018, 11:15:10 am by Jay_Diddy_B »
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #212 on: December 12, 2018, 04:44:24 pm »
Well c3 was out of spec,changed and its fine,reads a bit low on high readings>5 ohm but thats ok,included some pics the last pic is a .6ohm resistor,cheers for your help,73 mvuv Paul.
 

Offline LeoH

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Re: 5 Transistor ESR Meter Design
« Reply #213 on: December 17, 2018, 01:58:05 am »
Hello all,

I followed a procedure (https://www.neatcircuits.com/meter-mult.htm, Method #2, Section 1 Voltmeters) to help estimate my panel meter's internal resistance and came out to be about 7500 ohm. With this value for internal resistance of the meter, will R24 still necessary and what will be the recommended value for it?

This is the meter I got recently  for this project:

 
 

Offline m3vuv

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Re: 5 Transistor ESR Meter Design
« Reply #214 on: December 17, 2018, 02:15:26 am »
if it helps i left out r 24,i just used a 20k multiturn pot instead of 10k,no reason its just what i had,r23/4 do is make it possible to zero the meter,ie go fully to the right with the test leads shorted!
 
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Offline Autoexe3219

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Re: 5 Transistor ESR Meter Design
« Reply #215 on: December 27, 2018, 02:22:44 pm »
Hey Guys

Here are the PCB files for a through hole version .





Eagle PCB Files Attached

Cheers

Rupert

What is the voltage of the capacitor(C2~C11)? 63V?
« Last Edit: December 29, 2018, 11:17:03 am by Autoexe3219 »
 

Offline Jay_Diddy_B

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Re: 5 Transistor ESR Meter Design
« Reply #216 on: December 31, 2018, 11:01:44 pm »
Hi,



The capacitor on the left, C10, has the battery voltage, so use a 25V part.
All the other capacitors have less than 5V on them. You can use any capacitors with a voltage rating with a voltage rating of greater than 5V. Most of the capacitors in the prototype would have been 25V or 50V parts.

Some people have used electrolytic capacitor in the C4 and C6 positions. If you do you can use larger values 10uF to 100uF with a 6.3V or greater voltage rating. They should be low ESR electrolytic capacitors.

Regards,

Jay_Diddy_B
 
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Offline battlecoder

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Re: 5 Transistor ESR Meter Design
« Reply #217 on: January 01, 2019, 12:04:58 am »
Thanks again, Jay_Diddy_B for sharing such a fantastic circuit.
Here are some pics of my build. Not the fanciest one but it gets the job done.

The PCB is the through-hole design you shared. Toner-transfered.
I got the meter from this ebay listing.
For my build/components R24 had to be around 20 ohm. Don't know if that's reasonable or normal, but it seems to be working properly.

The LED was an afterthough so it's soldered directly to the leads of two resistors. (Yikes) Please ignore all the reinforcement I had to add around the rocker switch; I was working with a drill since my dremel is currently out of service and things got slightly out of hand  ::).
« Last Edit: January 01, 2019, 06:01:15 pm by battlecoder »
 

Offline kripton2035

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Re: 5 Transistor ESR Meter Design
« Reply #218 on: January 01, 2019, 07:29:25 am »
well it's a really clean build ! congrats.

Offline LeoH

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Re: 5 Transistor ESR Meter Design
« Reply #219 on: February 19, 2019, 02:21:28 am »
Hi Mauro,

After trobleshooting my board, I noticed that there is a track overlap in the version of yours.

I imported the project files to KiCad and to be certain, compared against the toner transfer provided.

Then the base voltage of Q4 measured correctly against the reference and meter deflected properly.

Check the figures.

Thank you!

Leonardo

 
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Offline mauroh

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Re: 5 Transistor ESR Meter Design
« Reply #220 on: February 20, 2019, 11:04:09 am »
Hi Leonardo, thank you so much for the correction and sorry everyone for the mistake.
Attached you can find the corrected files. To be safe I've also updated the attachements on the old posts.

I think this will solve the mistery of the M3VUV board not working properly.

Thank you
Mauro

Edit:Do not use files with version below 1.3. There was a mistake in the routing.
« Last Edit: March 01, 2019, 04:29:22 pm by mauroh »
 
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Online bd139

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Re: 5 Transistor ESR Meter Design
« Reply #221 on: April 07, 2019, 04:51:38 pm »
Big thanks to Jay_Diddy_B due. A wonderful circuit that works nicely  :-+



 

Offline picofarad

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Re: 5 Transistor ESR Meter Design
« Reply #222 on: May 01, 2019, 08:56:15 pm »
Nice build! I'm building this ESR meter too. I see that you used a 100uA meter. What value did you use for R24 and the pot? The only ammeter I was able to find cheaply is a 100uA but I'm struggling to find the right value for R24.

I'm also hoping that Jay_Diddy_B will help me to figure out the right value!
 

Online bd139

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Re: 5 Transistor ESR Meter Design
« Reply #223 on: May 01, 2019, 09:10:12 pm »
I can't remember off the top of my head and didn't write it down unfortunately ... I'll go and take it to bits and have a look. Give me a couple of mins  :-DD

Edit: ok I had a look and it was literally just the 10k pot and the meter movement across C5 (22n one). No series resistor. Movements are difficult to blow up with the source impedance of that circuit so I must have just skipped it. Works fine though!

Got to say that this thing has saved me a fortune in capacitors so far!
« Last Edit: May 01, 2019, 09:15:06 pm by bd139 »
 

Offline picofarad

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Re: 5 Transistor ESR Meter Design
« Reply #224 on: May 01, 2019, 09:59:20 pm »
Oh thanks! I'll try bypassing R24. I've already etched and partially populated my board... waiting for those 1N5711 diodes to arrive  :palm:
 


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