This interesting digital counter with relays with complementary outputs was found in the Radio Electronics magazine of October 1961. The supply voltage is in accordance with the relays used.
We found this circuit in a magazine 73 from the 90's. It is a circuit indicated for radio-amateur...
In the figure we have a 9V source using a 5V 7805 regulator. The circuit is from an American...
If you have an old cassette player or bought one from a junk shop, you can set up a small table...