5 Transistor ESR Meter Design

[Fisher77]

Thank you for the advice, I will try with other diodes 1n4007 for example, also do you know where I can get a 50uA? On ebay they dont specify this spec.

Here is a good source for people that live in the UK: https://www.esr.co.uk/electronics/products/frame_test-panel.htm

[Jay_Diddy_B]

How would a 1N34A work instead of a 1N5711?
I have now other substitute in my junk and is the only other part I do not have.

The 1N34A should work fine. Try them and let us know.

Regards,

Jay_Diddy_B

[Fisher77]

Jay_Diddy_B what is the procedure for working out the resistance of R24? I see on the schematic that it has an x to it, so I figure there is some formula you have to work out to get the proper resistance for it. Or is R24 the 10K pot? I am confused again. One schematic shows R24 and a pot, and another shows just the R24, and states 50uA & Pot.

[SeanB]

R24 is the 10k pot. Use to calibrate full scale and then the rest will be approximate, somewhat nonlinear but usable. To get an accurate scale you have to use some low value resistors to mark your scale appropriately.

[Fisher77]

R24 is the 10k pot. Use to calibrate full scale and then the rest will be approximate, somewhat nonlinear but usable. To get an accurate scale you have to use some low value resistors to mark your scale appropriately.

Thanks SeanB, that cleared it up. What threw me off was that 0ne schematic had a R23, and R24 on it. But I am guessing when Jay_Diddy_B updated the schematic to show the Pot connections he had to label it. If you give me a schematic for a International,Freightliner, etc. truck I can tell you where anything is. Still learning to read the electronics schematics. On the low value resistors, I assume you mean 1%. What values would I need to calibrate the scale?

[Jay_Diddy_B]

Hi,

The original calibration procedure was described in this message:

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

You need  5 x 1 Ohm and 4 x 10 Ohm  1% resistors and by using them in various combinations of series and parallel you can get a good selection of values.

I also built a test board described in this message:

https://www.eevblog.com/forum/projects/esr-meter-adapter-design-and-construction/msg343855/#msg343855








R24

The value of R24 depends a little bit on the meter being used. It is in series with the pot and the meter.

I am in the process of building another meter right now. I will let you know.

Note R24 is typically 12k Ohms but may need some adjustment. The 10K pot is place in series with the 50uA meter.



Regards,

Jay_Diddy_B - recovering ESR_nut

[Radio Tech]

Got my through hole version just about done. Have to play around with the calibration and do some test.
Decided to give an old piece of gear a new identity.
The range switch is now the variable resistor.
Zero ohm switch now has a BNC jack and also connected to the + / -.
Going to put an ON/OFF switch in the other hole.

[Jay_Diddy_B]

Hi group,

I have completed the assembly of the thru-hole version. Here is a picture of the assembled board:



If you are trying to read the colour codes, most of the resistors used are 1 or 2% so they have an extra band.

I also substituted a 3.3 Ohm resistor for R10, because I didn't have any 3.0 Ohms.

Here is a photograph of the board being tested:



I have the board hooked to a General Radio Decade box, out of camera, set to 1 Ohm.

I needed a 12k Ohm resistor in R24 position.

Regards,

Jay_Diddy_B (Recovering ESR_Nut)

[Jay_Diddy_B]

I have BC5xx transistors. Could they be substituted?

Wilfred,

You can use pretty much any silicon transistors in the design. Any that have the following spec.

Vce >20V
Hfe > 100
Ic > 50mA

You need 4 NPN and 1 PNP.

The only critical parts are the two diodes D3 and D4. These should be small signal Schottky or 1N34A etc.

Do not use 1N4148  - too much voltage drop or 1N5819 - too much capacitance.

Regards,

Jay_Diddy_B

[kripton2035]

Hi group,
I have completed the assembly of the thru-hole version. Here is a picture of the assembled board:

What are the small pins you can attach hooks on them ? what are their names, where did you find them ?
I came to buy the Keystone test points, but they are really too expensive, and did not find them in europe the shipping is more than the test points !

[Jay_Diddy_B]

What are the small pins you can attach hooks on them ? what are their names, where did you find them ?
I came to buy the Keystone test points, but they are really too expensive, and did not find them in europe the shipping is more than the test points !

Kripton2035,

I have two types of those pins in my collection. I used Keystone 1502-2 on the board shown. I made my own tool for pressing them.





They are $0.50 each in small quantities, dropping to $0.20 in large quantities. I was able to buy a bag of them on eBay. They were still expensive around $0.05 each.

I also have a bag of smaller pins made by Mill-Max:



I can't remember where I got them. These ones are designed for 0.032" board.

Try searching for "Turret Solder Terminal" on eBay.

As an alternative try looking for 'vero pins'.

Good Luck !!

Jay_Diddy_B

[Radio Tech]

Time for a bit of troubleshooting now. I can short the leads, zero meter. But when I disconnect the leads my meter reads just below half scale. Disconnect power and meter returns to normal. Not sure if D3 and D4 have a problem in the circuit.

[Jay_Diddy_B]

Time for a bit of troubleshooting now. I can short the leads, zero meter. But when I disconnect the leads my meter reads just below half scale. Disconnect power and meter returns to normal. Not sure if D3 and D4 have a problem in the circuit.

Hi,

Check this message:

https://www.eevblog.com/forum/projects/jay-diddy-5-transistor-esr-meter/msg933224/#msg933224

Then report back.

Further to my last comment, check Q5 first. You should have a square wave on Q5 collector. The symptoms you have are consistent with Q5 not working.


Regards,

Jay_Diddy_B

[alin_im]

what type of diodes are d1 and d2 can 1n4007 replace them ? if not what is a replacement for them ?

[Jay_Diddy_B]

what type of diodes are d1 and d2 can 1n4007 replace them ? if not what is a replacement for them ?

alin_im and the group,

The diodes D1 and D2 are protection diodes. You can use any diodes from the 1N4001 to 1N4007 family.
They provide some limited protection against damage from a charged capacitor.

Regards,

Jay_Diddy_B

[Bryan]

For those interested in software for creating panel meter faces. Works under Win 10 if you run as administrator and XP compatibility. I am sure there is other software out there.

http://www.tonnesoftware.com/meter2.html

[bitseeker]

Since I think this 5 transistor ESR meter design is very clever, I decided to take a closer look at it in my latest "Circuit Fun" video

Thanks for covering this, Alan. I didn't see the thread when it originally started and it looks like there's quite a bit of new activity as a result.

[Elrod]

Hi all.  I used the Hopesun PM-2 meter in my ESR meter.  I wanted to share my meter scale graphics.  May be useful for someone with this same meter.

Elrod

[Bryan]

Tried opening the dxf file in DXFviewer and all that is displayed is a black screen? Tried different encoding options that are available in the viewer, but same thing.

[alin_im]

What programs did you use to draw the meter scale  ?

Is there any special program that I can use (except Meter that costs 35 dollars, too much money for one meter) ?

In the worst case I will use Illustrator, but it will take some time.

[kripton2035]

hem ... illustrator is far more money than $35 for one meter ...

[alin_im]

hem ... illustrator is far more money than $35 for one meter ...

I have a friend that has it and can help me, but I wanted something that I can use in the future without the help of others.

[Elrod]

I drew the PM2 scale in QCAD Pro on Linux.  Here is a PNG version as well as an older format DXF file.  Maybe you can open it.

[felixna]

Hi all,

I wanted to share my rebuild of this fine ESR-meter with you. Not the most beautiful build but most parts were already here and it works perfectly!

The instrument is this cheap chinese HUA 85C1 meter: http://www.ebay.de/itm/291493659126 - not the most precise one (class 2.5 is exaggerated, it's more like a 4), but good for the job.

The scale for the meter was done with Inkscape and is attached in the ZIP file.

Thank you, Jay_Diddy_B for this great circuit!

Cheers,
Felix

[Jay_Diddy_B]

Felix,

Congratulations !!!

Looks good, thank you for sharing!!

Regards,

Jay_Diddy_B