This elaborate mixer is from an Electronics Today International from the 80s. Operational amplifiers are common and resistors with no value determine the gain of the amplification steps.
Maxim MAX20056B 6 Channel High Brightness LED Controller Maxim Integrated makes available through...
This circuit is an isolated shield for microcontrollers such as the Arduino, MSP430, PIC and...
This circuit was suggested by Sprague Electric in an 80's documentation. The circuit uses a...