RCA BA103a racked with remote (pic's)

[Moby]

I finally racked these two guys. They were laying around for some time  :-[ I added one more class A buffer stage with API output tx  remote gain and trim controls because I need all gain controls near my desk, phase, pad and p48. It started like the quick design but ended with the full box

 

[mjrippe]

Nice!  I love the RCAPI logo 

 

[emrr]

From the remote, I'm guessing you kept the original gain method on the 1st op amp, and added a trim with the new output stage? 

Looks great. 

 

[Rochey]

whats the remote protocol?

 

[Moby]

From the remote, I'm guessing you kept the original gain method on the 1st op amp, and added a trim with the new output stage? 

Looks great.

Thanks, yes, RCA's gain structure (with few more gain points) but switch is replaced with relays. The trim is simple attenuator between two stages.

Posted by: Rochey
« on: Today at 05:51:20 AM » Insert Quote
whats the remote protocol?

Nothing fancy, purely passive thing with remote DC voltage controlled from the switch box. I was thinking about other (digital controlled ) option but since I'm not experienced with programming finally decided to go this way. Btw, I learned few things during this design. For example, that relay coil voltage must be super clean because if it's not, it reflects 50hz over the signal contacts.