This one-tube circuit is equivalent to the previous one. We find it in a 1924 book by Gernsback, Power is made by batteries.
We found this simple alarm circuit in a 1981 documentation. As we can see, it is a car alarm...
We found this circuit in an English magazine from 1976. The magazine no longer exists, but just...
Suggested by General Electric in a 1968 documentation this integrated amplifier uses a component of...