Ruby amp debugging help

[electronoobz]

i installed the ic and the jfet correctly.. there's a hiss and buzzing noise when im touching pin 2,1,8..

any clue?

 

[(*steve*)]

Schematic?

The most probably reason is that you're amplifying hum that your finger is inserting into the circuit.

 

[electronoobz]

im doing it to check if it will have sounds but when im using the jack there's no sound amplified.. but again will sound if i touch the pin 2..

when im touching 1 and 8 (which is the gain) there's a lot of buzzing noise which means it is really working.. just doing it for check

 

[(*steve*)]

Do you get the sound if you touch the gate of the jfet?

What is the voltage across the 3k9 resistor?

 

[electronoobz]

yes i hear a reaction when im touching the gate and source... any more clue??

 

[electronoobz]

i remember asking you if i could use 2n5458 you said yes.. i really think that is not the problem.. the ic is working also.. so very sad because of this...

 

[(*steve*)]

OK, so you hear the buzz when touching the input, but not when the input source is attached.

What is the input you're connecting it to?

Have you tried a capacitor in series with the input?

Is it possible you are using a mic that requires phantom power?

 

[electronoobz]

im using my guitar.. cant hear any sound.

my guitar electronics is fine.. i tested it in out power amp

 

[(*steve*)]

Have you tried a capacitor in series with the input?

Are you connecting the ground?

The idea is to answer ALL questions, not just the last one.

 

[electronoobz]

Have you tried a capacitor in series with the input?

Are you connecting the ground?

The idea is to answer ALL questions, not just the last one.

yes i did... caps series with the input?? not yet.. what value anyway? 100uf?

 

[(*steve*)]

0.1 uF to 1 uF should be fine for testing.

 

[electronoobz]

ok thanks!!!

 

[electronoobz]

So sad, bad luck today.. Bought wrong value

Can I use 4.7uF?? Which side for positive??

 

[(*steve*)]

Yeah, sure. Connect -ve to the gate of the JFET

 

[electronoobz]

bad news... not working still

 

[electronoobz]

i tested my ruby mp with my multitester.. (volt tester) and put the first one to ground and the other one to every part

pin 2,3,4 has no voltage (3 and 4 is conencted to ground)

 

[Relayer]

I hope you realize you're using an RF JFET, not suited for audio.
Regards,
Relayer

 

[davenn]

I hope you realize you're using an RF JFET, not suited for audio.
Regards,
Relayer

Hmmm, yeah that thought crossed my mind too.
The lowest freq's I have used them on have been between 200 - 500kHz
for receiving aeronautical NDB beacons
I'm not sure how they perform below that ... maybe no problem ??

Dave

 

[electronoobz]

but i asked steve a long time ago about that.. i also told him that im making an amp.. he said 2n5458 is ok

 

[davenn]

but i asked steve a long time ago about that.. i also told him that im making an amp.. he said 2n5458 is ok

but are you using that one or the MPF102 as shown in the cct diag ??

Dave