The sensors of this liquid alarm are formed by two pieces of wire with the ends peeled off. The relay depends on the supply voltage that can be between 3 and 12 V. The transistors can also be the BC548.
This circuit was found in old documentation. The components can be replaced by modern ones. The...
This transistor circuit consists of a well-known bass and treble control configuration. The...
With the circuit shown, you can have a fast response with a Darlington configuration. The circuit is...