This circuit is from a Ferranti publication of 1968. The circuit generates a signal according to the crystal. The transistor may be a modern equivalent.
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...