At higher values, the circuit can reach timings longer than one hour.
Among the possible applications, we suggest systems of automatic shutdown or automatic timing activation of several devices.
The type of controlled load depends exclusively on the contact capacity of the relay used.
For applications where a battery is used as the power source, low power relays should be used.
The S1 pressure switch is optional as a reset and also to ensure that at the beginning we have a complete timing with the capacitor load from zero.
In Figure 2 we have a suggestion of a printed circuit board for the assembly of this timer.
This board provides the use of relays with DIL socket.
For higher current relays, the design of the board should be redone according to the arrangement of the terminals or even to be built outside the board.
CI-1 - 4093 - CMOS integrated circuit
Q1 - BC548 or equivalent - general purpose NPN transistor
D1 - 1N4148 - general purpose diode
R1 - 100 k ohm x 1/8 W - resistor - brown, black, yellow
R2 - 4.7 k ohm x 1/8 W - resistor - yellow, violet, red
P1 - 1 M ohm at 4.7 M ohm - potentiometer
C1 - 10 uF at 2 200 uF x 16 V - electrolytic capacitor
C2 - 100 uF x 16 V - electrolytic capacitor
K1 - 6 or 12 V x 50 mA or more sensitive - relay
S1 - Pressure switch - optional - see text
Miscellaneous:
Printed circuit board, relay socket (optional), wires, welding, etc.
