Found in a Motorola manual from the 1980s, this circuit uses components from the era. The circuit controls lamps from 5 to 48 W from 12 to 14 V.
This filter for the 300 Hz to 3 kHz range was found in an American documentation from the 90's....
Radio Electronics published this circuit in a 90's edition. The circuit makes use of an uncommon...
We found this circuit in a 90s Popular Electronics. The operational amplifier can be replaced by...