Pro Audio Design Forum

I did a patent search on this a couple years ago and chased down the inventor, He was not close to selling a commercial product. I have long though that the kitchen freezer/refrigerator needs to be combined with a hot water output. Excess hot water needs to dump into hot water tank for use. With eno...

While I don't need more projects, I think I will experiment with making a slow "crock pot" like cooker using a Peltier heat transfer module. It seems like this would be a nice idea for counter top cooking in the summer months while simultaneously cooling down the kitchen. :lol: :lol: I'm t...

There are other improvements inside the newest generation VCA related to the semiconductor process. VCAs involve PNP and NPN transistor pairs performing current ratioing. The NPNs and PNP are more similar to each other, in these latest generation parts for better polarity symmetry. While some of the...

I've already closed the schemo so I won't revisit. It did not look like that to me, since it is making the gain rate of change larger above a certain voltage. I can imagine a VCA getting a little squirrely when commanding silly amounts of attenuation, especially if using just one control port. VCAs ...

Is this a test? OK luckily for you I still had this schematic open,,, that opamp with diode connected across it can only conduct in one direction, so for the direction that the diode conducts the opamp will hold the - input to same voltage as the + input, for input conditions where the diode in not ...

While that schemo was not that easy to follow it looks like the send to the VCA is through an X kohm resistor (10k?) and at the VCA there is probably an X ohm resistor to ground to form the bottom leg of a simple voltage divider. To convert from 6 mV/dB to 30 mV or whatever, you need to scale one or...

I read most of your post, I was not familiar with the specific nomenclature "charge" amp , so I googled it. Apparently a charge amp is an amplifier configured as an integrator, or current integrator. For you opamp selection you should probably look for opamps with low input bias current (l...

Time for another pseudo-repair anecdote. My recent equipment failure is the control board for my big dog coffee bean roaster. This unit has a huge LCD display with multi-color back light for the LCD. I don't use a fraction of the programming features but I use the hell out of my roaster, roasting ne...

This one says they use "feedback suppressing circuitry" , maybe they are lying, it didn't look very expensive.

JR

Switching? :lol: It is interesting to see the cost engineering dynamic. Back then it was cheap to throw an extra transformer at it to reduce the relatively expensive active device (tube) count. I recall back in the '60s seeing an early solid state amp that used interstage transformers just like an o...