Simple analog vu-meter driver ?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Wrapping up some projects...

I cased an headphones amplifier into an old tape recorder and it has a pair of nice analog VU-meters (Kyoritsu KM-86) on the frontplate. I'd like to use the meters to roughly monitor the output level into sennheiser HD650 (300 ohms). I don't need perfect ballistics. Cheap and easy to breadboard are more important factors here.

Would the following circuit do it ? (it's mostly a simplification of http://www.jlmaudio.com/AT51 DIY VU.pdf ).

attachment.php


R7-R8 are trimmers to adjust the vu-meter (I'm aiming to set the 0VU at a max "reasonable" level for long term listening). The headphones amplifier I'm using won't clip before +/-13V (peak) into 300r, so I need the to pad the signal going into the tl072. 10k in // with a 300r load is ok.

Thanks :)
 

Attachments

  • vumeter.JPG
    vumeter.JPG
    47.7 KB · Views: 7,940
Thanks George. I'll save this schematic, very simple indeed :)

I put the first one together this evening. It works quite ok. 100uf is too much in // with the meters I have, it makes it too slow. I'll try 10uf later on.

Btw, I enjoyed some fireworks in the process. Soldered the PS backwards and fed a poor tl072 -20Vdc. It didn't explode but started fuming and slowly split in two right in the middle. Oh happy times.
 
Thanks George. I'll save this schematic, very simple indeed :)

I put the first one together this evening. It works quite ok. 100uf is too much in // with the meters I have, it makes it too slow. I'll try 10uf later on.
Sorry could I ask if you're referring to the one-transistor circuit, I've planned to try that out too. Did it originally have a 100uF cap., it's not in the circuit?
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.