In DC circuits, the SCRs must be cut off or their anode and cathode short-circuited to be switched off so that the voltage between them drops to a sufficiently low value to cut off the current. In the circuit shown in figure 1 we start the circuit by pressing S1 for a moment.
Shutdown is done by pressing S2 when the capacitor discharge current short circuits the SCR by turning it off. This is an efficient way to remotely disconnect DC circuits fed by SCRs.
For a TOC106 the maximum recommended current is of the order of 3 A. Remember that there is a voltage drop of approximately 2 V in the SCR that must be compensated in the power supply. The SCR needs a heat radiator and the operating voltage of the capacitor must be greater than that used in the power supply.
In figure 2 we have a suggestion of printed circuit board for implementation of this mini project.
MATERIAL LIST
SCR - TIC106 - Silicon Controlled Diode
C1 - 10 uF x 16 V - electrolytic capacitor
R1, R3 - 10 k ohm x 1/8 W - resistor
R2 - 2.2 k ohm x 1/8 W - resistor
S1, S2 – Push buttons NA
Several:
Printed circuit board, heat radiator for SCR, wires, solder, etc.
