Found in a 90s Popular Electronics, this circuit fires an old flash of xenon from the pulse of light received by a sensor. The trigger, however, is made with a delay given by C2.
Found in a 1960 Sylvania manual, this circuit is intended to measure audio signals frequency....
This circuit is indicated for measurement bridges as a null detector, thanks to the logarithmic gain...
National Semiconductor suggests the circuit in the figure that uses two operational amplifiers of type...