When the sensor K1 is activated, the bistable formed by IC1-a and b acts, and the SCR is turned on. Then, the lamp remains on until the bistable changes its state again by the action of X2.

The circuit is a half-wave control, because we are using an SCR, but you can easily alter it to operate as a full-wave control by putting a full-wave bridge on the ac power line input.

The SCR is a 200 peak inverse voltage (PIV) device that must be mounted on a heatsink. Lamps or heaters (resistive loads) can be controlled in the range between 5 and 200 W.

A schematic diagram of the Power Bistable with Magnetic Switches is shown in Fig. 1.

 

Figure 1 – Schematic diagram for the project
Figure 1 – Schematic diagram for the project

 

Be careful with the wires to the sensor. These wires are not isolated from the ac power line.

Positions of the polarized components (diodes, electrolytic capacitors, SCRs) must be observed.

Erratic operation of the circuit, in case of long wires to the sensors, can be reduced by reducing the values of R1 and R2. You can use resistor values as low as 10 kg in this function.

 

IC1 - 4093 CMOS integrated circuit

SCR - TIC106, (3106 or MCR106 200 PIV silicon controlled rectifier

D1, D2 1N4002 or equivalent silicon rectifiers

X1, X2 - Reed switches

L1 - 5 to 200 W 117 V incandescent lamp

F1 - 5 A fuse and holder

S1 SPST toggle or slide switch

T1 - 6.3 V, CT, 300 to 500 mA transformer

R1, R2 -100,000 ohm, 1/4 W, 5% resistors

R3 - 4,700 ohm, 1/4 W, 5% resistor

R4 - 1,000 ohm, 1/4 W, 5% resistor

C1 - 1,000 11F, 25 WVDC electrolytic capacitor

 

 

Datasheets


N° of component