Found in a 1967 Electronics World, this preamplifier uses an integrated circuit from that time, difficult to obtain today. The maximum frequency is 15 kHz.
This circuit provides a signal of higher frequency the greater the intensity of the light incident on...
This circuit was obtained from a 1978 Practical Wireless. It generates a low frequency, low...
This circuit can be used as a lockable shield. A pulse activates the relay that remains on even...