jlm audio round vumeter

Hi,

¿does anyone know if the JLM AUDIO 34mm round vumeters have internal diodes? if they do, ¿how many?.

i'm building an unbalanced line level input buffer for it.

Thank you very much.

JAY X

Don't think they do...

Hi,

Ok, i will add four diodes to the buffer.(1N4148),  See what happens...

Thanks a lot,

JAY X

jwhmca said:

Don't think they do...

Click to expand...

Confirrmed,there aren't diodes in it.

Cheers,

Udo.

Hi ,

Yesterday i build the buffer circuit and still doesn't work...

Here is the schematic... maybe you can see what is ok or wrong...

JAY X

doesn't work properly or doesn't work at all? To work properly the diodes will need to be germanium or something like BAT85. If not working at all have you checked what you have on the output of the opamp?

Hi Squib,

Before placing the diodes and the 3k6 resistor, i tested the circuit with the 100R output resistor conected to the + input of the vumeter, and the - input of the vumeter conected back to the psu ground. In this conditions i apply power and the needle went all the way right, stuck there until i shut down power.

After that i placed the 3k6 resistor: the needle did not move at all
after that i added the 1n4148 diodes: no needle move.

I will try bat85 diodes, and re- check the circuit.
In any case, ¿can this circuit work?

I forgot to mention that i used a 10k trimpot instead of 22k...

Thanks a lot,

JAY X