Help needed with building a JFet-Matcher

[Gokarna]

Hello to everyone,

in order to build some phaser effects, I started to build a jfet-Matcher, but the da.... thing doesn't work and I can't find the error.

I attached my drawings to this post.

I copied this circuit:

Testing and Matching JFETS | Stompville

I didn't used a etched pcb, build on tagboard and wired the 3-position switch seperatly to the circuit.

For power supply, I used a print transformator ( 2x 9V with 0,75VA), followed by 2 rectifier circuit including voltage regulators, one circuit supplies the two digital meters ( Volt & Ampere, they light up), the other the jfet - circuit.

The connection from C to Pin 1 is soldered at the 3-position switch, the coloured dots in my drawing are the wires to the switch.

I twice checked all the soldering points,checked all the connections, tested the opamp, and used the multimeter to measure the voltage without plugged-in opamp/meters.

Everything looks fine, the only thing I'm not sure about is the voltage on (opamp-)pin 3: the multimeter only shows 0.98 volts.
Am I right, that resistor R1 and R2 are used as voltage divider ? So theoretically, it has to be 4,5 V ?
The original circuit also shows on the very right bottom a soldering point to ground - do I have to connect this ? (the enclosure is of plastic and the 230V power supply is without groundwire)

The last idea I have is that 0,75VA (AC) from the print transformator might not be enough to make the jfet-matcher work..


I'm thankfull for every tip or help

Best regards

Gokarna

[Gokarna]

Original schematic added

Hello,

No idea from anyone here, where the problem is ?

Or did I start this topic in the wrong category ?

Below, you can find also the original schematic for the jfet-matcher from Stompbox.co.uk.

Any comment is welcome.

A nice weekend to all of you,

Regards

Gokarna

[Jazz P Bass]

Don't confuse the 'GND' symbol with Earth Ground.
It is simply a label.
Pin 4 of the opamp should be connected to the 'Battery Minus'. (which can be considered 'Ground').

[J M Fahey]

Germans complicate things

Just build the *original* circuit, without multioption selectors, ampere meters, etc.



That's all you need.

[Gokarna]

Hello,

thank you very much,Jazz P Bass and J M Fahey for your comments.

Pin 4 of the opamp should be connected to the 'Battery Minus'. (which can be considered 'Ground').

It is, the "Jumper" (see my drawing) connects pin 4 & 5 with battery minus/ground.

Germans complicate things

Yes, you might be right . I liked to build this special jfet-Matcher also for the pleasure of building a nice device.

Just build the *original* circuit, without multioption selectors, ampere meters, etc. That's all you need.

Would be an alternative. But not satisfying im my case. I would like to know/learn something more about electronics, even I'm stuck now.

So "Germans like complicated things", if you like.

Any other Ideas, whats wrong with my built ?

Best regards

Gokarna