This high impedance circuit was found in 1967 documentation by Ferranti. The original operational amplifier is from that time. The circuit can be implemented with modern equivalents.
This circuit was obtained from a 1978 Practical Wireless. It causes an LED to flash at a frequency that...
We found this circuit in a 1986 publication. However, as it is based entirely on 555 integrated...
This circuit with an integrated circuit of the time was found in the magazine Radio Electronics of April...