This timer is ideal for small aplications. Due to its simple structure, its usage and nevertheless its universal character, this mini timer is usable in the most current applications needing time intervals, from some seconds through approximately 60 minutes. By simple modifications it is possible to adjust the maximum time and the timing scale, as necessary. A strong output, made by a relay, permits to adapt, on the input and the output, whatever apparatus.
The circuit is constructed around the classical timer NE555. Parts: R1=1K R2=10K R3=4K7 R4=1K R5=10K R6=4K7 R7=1K RV=2M2 D1=1N914 C1=100nF C2=100uF/16V IC1=NE555 T1=BC547 RY=12V RELAY