Time Delay Relay Circuit

C1 10uf 16V Electrolytic Capacitor
C2 0.01uf Ceramic Disc Capacitor
R1 1 Meg Pot
R2 10 K 1/4 Watt Resistor
D1,D2 1N914 Diodes
U1 555 Timer IC
RELAY 9V Relay
S1 Normally Open Push Button Switch



Notes:
1. R1 adjusts the on time.

2. You can use a different capacitor for C1 to change the maximum on time.

3. S1 is used to activate the timing cycle. S1 can be replaced by a NPN transistor so that the circuit may be triggered by a computer, other circuit, etc.

Temperature Regulator Circuit

SWR And Power Meter

Stere Pho Preamplifier (RIAA Filter) Circuit

step-down converter (MC34063A) Circuit

The step down converter is the power unit to make the output voltage which is lower than the input voltage. The converter which was made this time makes +2V to +10V output voltage with the input voltage of +12V. Because it makes the limitation value of the input electric current about 1.3A, the maximum with the input electric power is about 16W.

SSB AF Filter Circuit

Scope calibrator Circuit