This Hughes circuit is from 1968. Equivalent modern components can be used. The input impedance is 1000 M ohm.
We find the original version of this circuit in an English publication (1986). It is a...
We find this circuit in a Popular Electronics of the 80's. The frequency range depends on C1 and...
We found this circuit in a 2004 documentation. The circuit consists of a standard lamp for testing...