This detector with ultra-low deviation was found in an American documentation from the 90s. Operational amplifiers are from that time. The power supply must be symmetrical.
This circuit shows how to control an astable configuration using the 555 IC. The control signal is...
This circuit is from an old operational amplifier manual. It appears elsewhere on this site and...
The circuit is from an 80's publication, but the components are current, only special type diodes...