This simple timer with unijunction transistor was found in an old American technical documentation. We can use 2N2646 for the unijunction and BC548 for the transistor.
In the figure we have a simple timer with the 555 feeding a relay directly. The circuit is from...
This is the power step of the previous circuit. Output transistors must be mounted on good heat...
We found this circuit in a publication of 1991. The audio amplifier is an operational that admits...