Equivalent transistors can be used in this circuit for automotive applications in the 1980s. The frequency is given by the capacitor and the current of the lamp depends on the LM195 transistor.
This is a Japanese commercial radio from the 60s. The circuit is listened to by phone and is...
The first circuit we present is ideal for matching the low impedance of transducers, such as...
We found this circuit in Motorola's Linear Databook in 1990. The component used is not common today....