5 Transistor ESR Meter Design

[Elrod]

My ESR meter using the Hopesun meter movement got dropped one time to many.  I had to replace it.  I got a different meter this time so I had to make a different meter scale graphic.  May be useful to someone.  The eBay listing just called it a 50uA meter.  Box has M2D 0-50uA written on it.

[sasa]

I have relatively recently made this quite useful circuit. I have used OA91, 1% resistors where is critical, common BC547 and BC557. It works extremely well, as well as with desoldered and in-circuit caps. This is my homemade board.

Since I have no any analog meter, I use plain digital multimeter. For in-circuit measures they are used quite short quality UTP cable wires. due lack of any quality test leads.  In this configuration, perhaps may be simplified a bit to use an op-amp and MCU with a LCD, however I'm quite happy with this bare design as well.

Thank you, Jay_Diddy_B, for this simple and very efficient  circuit!!

[transistor12]

Thank you very much for tru-hole efforts .

[Efcis]

Hi Jay_Diddy_B et al.

1/ What is the reason why C3 and C8 have different values (10nF vs 22nF) ?

2/ Several builders seem to use electrolytics caps for C4 and C6 (2.2 uF). Are their own ESR not too large compared to ceramic / MLCC ones ?

Thanks !

[Jay_Diddy_B]

Hi Jay_Diddy_B et al.

1/ What is the reason why C3 and C8 have different values (10nF vs 22nF) ?

2/ Several builders seem to use electrolytics caps for C4 and C6 (2.2 uF). Are their own ESR not too large compared to ceramic / MLCC ones ?

Thanks !

1) You can use 22nF in both locations.

2) The ESR of C4 and C6 should be small. <10%, of the resistors they are in series with. If use an electrolytic you can use a larger value to get the low ESR.

Hope this helps.

Jay_Diddy_B

[hugo]

1/ What is the reason why C3 and C8 have different values (10nF vs 22nF) ?

The LTspice schematic shows both capacitors as 22nF.

2/ Several builders seem to use electrolytics caps for C4 and C6 (2.2 uF). Are their own ESR not too large compared to ceramic / MLCC ones ?

They have used what they had available I guess, both capacitors are in series with a 33 ohm resistor so ESR does not matter.

[Thebighat99]

Could someone be so kind to let me know what watt the resistors should be.  I am very new at this but would like to build this.

thanks in advance.

[EntropyWizard]

You should be able to use most any resistors you have available. Most builds seem to be using typical 1/4 or 1/8 watt through hole resistors. The 1/10 watt surface mount resistors should be fine as well.

[Jay_Diddy_B]

Could someone be so kind to let me know what watt the resistors should be.  I am very new at this but would like to build this.

thanks in advance.

I used 1/10W on the surface mount (SMD) version and 1/4W on the through hole version. These are the standard sizes. Nothing special in this design.

Good luck if you decide to build the ESR Meter.

Regards,

Jay_Diddy_B

[m3vuv]

hi mauroh,ive etched your design of board but cant see where the components go,is there a silk screen for it?,tried making p diddys board but found the tracks way to close together!,cheers m3vuv.

[mauroh]

Attached you can find my update Eagle design of the through hole version I posted 2 years ago where I added the PDF of the "silkscreen" with the component values to be printed and applyed on the top side.  (I also updated the old post).
I just made few changes only to the layout to the Jay_Diddy_B Design of R.Hirst Design (I left all the names on the silkscreen ).

The idea was to have a super easy layout that can be toner transferred and also built on a veroboard, since all the holes are on a 100mil grid as the traces.

Please let me know if you will build it (post pictures...) and if you have any suggestions.
The attached PDF of the PCB is mirrored to be toner transferred.
Do not scale it and verify the print dimension against the measurement (70*43mm)

Mauro

Edit:Do not use files with version below 1.3. There was a mistake in the routing.

[Jay_Diddy_B]

Hi,

Looks good!

Thank you for sharing your board layout.

Regards,

Jay_Diddy_B

[mauroh]

Hi Jay_Diddy_B!!
All credits goes to you for the design and to koogar (Rupert Hirst) for the PCB Layout on Eagle.
I have only tweaked the PCB Layout to be easily built on a perfboard or etched with the press&peal method.

I report here your notes to koogar on the design:

- D1 and D2 can be replaced by 1N4001, 1N4002 etc or 1N4935. These diodes take a beating if you connect a charged capacitor to the terminals.
- D3 and D4 are critical, the 1N5711 will be fine. You need low capacitance small-signal Schotky diodes.
- You want a panel mounted potentiometer for R23. You have to zero the meter to adjust for the lead resistance.

Hope it will help someone to easily build this meter 

Mauro

[BravoV]

I report here your notes to koogar on the design:

- D1 and D2 can be replaced by 1N4001, 1N4002 etc or 1N4935. These diodes take a beating if you connect a charged capacitor to the terminals.

Additional report, my friend who successfully built this great ciruit, on D1 & D2 he was using "used" 1N4007 diodes salvaged from dead CFL bulb, and he sort of joked and bragged as they're "proven" to survive high mains voltage and temperature in the bulb.   

[joseph nicholas]

Thanks muroch for your pcb layout for this.  I am waiting for some diodes from ebay to try and complete this circuit.

[m3vuv]

hi,nice work,is the  silkscreen pdf mirrored?,73 m3vuv.

[mauroh]

No, only the bottom side is mirrored.
The idea was to print the silkscreen on paper, gluing it on the top side.

My suggestion is to install Eagle and print the bottom/top/silkscreen depending on which method you prefer to use to build the board.
For instance I'm using an old pen plotter (with a permanent marker) to print simple boards like this.
In this case the pdf is useless and I'm using Eagle CAM processor to optimize all the plot parameters.

Mauro

[joseph nicholas]

Hi, I'm attempting to use mauroks pdf and the holes dont exactly line up with the vero board but Im going to continue to try to build this when I get all the components together.  It does look doable but lets see. 

[mauroh]

Hi  joseph nicholas, thank you to point this out!!
  the only holes that dosn't line up with the 100mil grid of a perfboard/veroboard, should be the base of the 5 transistors and the power connector.
As you can see in the attached picture, I left some room on each side of the transistors to allow it to be fitted at your convenience.
Regarding the power connector I didn't apply it and used the wires ofthe 9V battery clip instead.

If other holes are misulligned please let me know, I can't see it.
If several holes are misulligned, most probably you need to adjust the print scaling. Do not scale the print to fit the page.

Mauro

[joseph nicholas]

The place I get my printing done seems to think that the pdf file is scaled correctly using the standard settings.  I think everything is close enough although it does seem that the pdf is just a tad small the way it is unless the vero board is off.  Anyway what you have provided is excellent and I think eventually I will get a few of these templates made and start to try to get the soldering started on the back of the vero board.  I suppose the way to go with this is to have it made at a pcb house in china but I prefer to do it like I outlined earlier.

Its amazing the amount of detail and work you have done on this, and thanks again even if I cant get it to work or if there is an error in the design or my construction.  Just a cool fun and very practical project.  I plan to get this stuffed into one of those cheap MF type analog multimeters you find from China.

[mauroh]

I've added couple of strip connector on the sides of the board and printed the pdf on 2 different laser printers to verify the holes alignment...
As you can see removing all possible rescaling/fitting options on the printers, it looks like it is close to the veraborad I have.

Always take the veraboard with you or a strip connector to verify the dimension of the strip BEFORE etching/press&peel!!! 

I've added also the bottom side NOT mirrored, this is usefull as reference, working on the bottom side of the veroboard.

Mauro

Edit:Do not use files with version below 1.3. There was a mistake in the routing.

[blackdog]

Hi Jay_Diddy_B,

I liked your design of the ERS meter so much that I thought I would build one too.
On two radio flea market's, I bought some 50uA meters for this ESR meter.

There is only one component that I have changed in the design, and that is the 5V stabilizer.
I had some low power LDO stabilizer in a TO92 housing and that is the: TSTS2950-50
The dropout voltage when loaded with this ESR meter (24mA) is less than 5.5V.
This allows me to extract as much energy from the 9V battery as possible.

Picture time!
To minimize errors, I mark the parts on a print in the diagram, not all parts are marked, because I did not think this was necessary anymore.


The top of the printed circuit board.
The structure is almost the same as the schematic, I think this is a pleasant way of building electronics.
Top left is the battery connection, the two connection pins at the bottom are for the D.U.T. the diode's ES1J wil come behind the banana jacks.
And the connection pins in the middle are for the meter, the top connection is for the +connection of the meter.
In the blue circle you can see R24, 12K for a 50uA meter, in the yellow circle is the only aberration, the 5V decouplig capacitor C9 under a angle.



The bottum of the circuitboard, no spaghetti wiring 
The top wire is the +5V power supply, the wire below that is the connection from Q3 that drives Q5.
And on the bottom is the -rail.



And yes, he worked on the first power on. 
The meter indicates 35uA when measuring a 1 ohm resistor.



Now it is time to look for a instrument box, I'll show it here when the project is done.
Nice project!

Kind regards,
Bram

[Jay_Diddy_B]

Hi Jay_Diddy_B,

I liked your design of the ERS meter so much that I thought I would build one too.

snip ...

Now it is time to look for a instrument box, I'll show it here when the project is done.
Nice project!

Kind regards,
Bram

Bram,

Thank you for your kind words. The layout that you made looks great !! Thank you for sharing.
I look forward to see the completed project.

Regards,

Jay_Diddy_B

[bitseeker]

Nice job, Bram. I like how your component layout resembles the schematic so well.

Note that "spagetthy" is spelled "spaghetti."

[joseph nicholas]

I like the removal of the big 7805 bjt, from the original design.  Nice improvement, makes the circuit look more elegant.