Using the LM3909 this circuit was found in the January 1992 issue of Radio Electronics magazine. Resistor R1 should be chosen according to the table given next to the diagram.
Found in a Popular Electronics from the 90s, this game can be seen in other configurations on this site. The...
With a 1 500 uFcapacitor this timer can reach times up to one hour. The capacitor must be of good...
This circuit appears in other articles in this section, but it is very interesting. It is a...