Drill Speed Control (CB1353E)

This simple half-wave control using an SCR, which may be TIC106, has been obtained from a US paper. D1 and D2 are 1N4004 and R1 is 2k2 x 5 W. The potentiometer is 470 ohms x 5 W (wire) and the resistor R3 is 33 ohms x 1 W.