Vu Meter driver

[Spencerleehorton]

OK, well making some headway, a 21k resistor with a 9V battery (reads 9.45v unloaded) connected reads +1.5db on the scale on one VU meter, 18k is +5db, 31.8k is 0db.
I used a 200k trim pot which make it easier.

nice little way to work it out with battery and trim pot!
now i just need to know how to convert the 31.8k into uA? for what meter it is.

 

[Spencerleehorton]

now when connecting through this cheap Vu meter driver when i test for AC volts on output and twiddle the trim i get from 0.03v to 0.09v so the circuit is working just hardy at all!!
so i'm assuming IC has blown or with battery connected not enough power.
will try more power, 15v i will start with.

 

[Spencerleehorton]

no difference when putting 12v through this VU meter driver, 0.775v going in 0.05v out?
i have put in a IC socket now which i should have done in the first place.
seller has said that this circuit definitely does work? with this meter or any other i cant see it working as it doesn't do what its meant to and that it DRIVE the signal!!!
for testing am i right in thinking that i can use 5532, OPA2604 for replacement for TL071?

 

[Spencerleehorton]

have finally got the needle to move from -20db to -18db using a OPA2604 with a 9v battery!!!
i will try and use 15v now.

 

[Spencerleehorton]

no luck with this cheap VU meter driver, will try printing this other pcb and get some TL071's

 

[Spencerleehorton]

Just wondered, in that Vu meter Buffer that Jano1954 has postedit asks for 1N5819 diodes, i have noticed these are 1A 40v diodes, could i use for instance a 1N914?

regards

Spence.

 

[Spencerleehorton]

Just powered up this VU meter and i get signal through, i cant seem to get 0db withy 0.775v 1khz going in and adjusting the VU meter trim? i can get -1db if i set signal gen to full (1.2v) and set to 10k!!!?
gotta test the rest of the Neve pre amp now!

 

[Spencerleehorton]

anyone know how i can get 0db with this VU meter buffer please?