Ton Giesberts
About the article

SCR Gate Pulse Generator

"Fire in the gate!" for thyristors and triacs

SCR Gate Pulse Generator
The old-school semiconductor device family called "Silicon-controlled rectifiers" or SCRs in short include thyristors and triacs. As opposed to many other semiconductors which can be tested and characterized to an extent with a plain old multimeter, SCRs require testing dynamically by applying 'firing' pulses to their gate electrode. The simple but effective circuit presented here employs the mains voltage to obtain synchronized gate pulses.
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The BOM (Bill of Materials) is the technically exhaustive listing of parts and other hardware items used to produce the working and tested prototype of any Elektor Labs project. The BOM file contains deeper information than the Component List published for the same project in Elektor Magazine. If required the BOM gets updated directly by our lab engineers. As a reader, you can download the list here.
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Component list

Component List


R1,R2,R4 = 100kΩ, 5%, 0.25W, 250V

R3 = 0Ω, 5%, 0.25W (or jumper wire). See text for important safety notices

R5,R6 = 1kΩ, 5%, 0.25W

R7,R8 = 2.2kΩ, 5%, 0.25W

R9 = 330Ω, 5%, 0.25W

R10,R11,R12 = 10kΩ, 5%, 0.25W

P1 = 1MΩ, trimpot, horizontal mounting



C1 = 15nF, 100V, 10 %, PET, 5.0/7.5mm pitch

C2 = not normally used, see text

C3,C4 = 100nF, 50V, 10%, X7R, 5.0/7.5mm pitch



D1-D4 = 1N4007, DO-41

D5,D6 = 1N4148, DO-35

T1 = BC547B, TO-92

T2 = BC557B, TO-92

IC1 = CNY65, DIP-4 HV (L x W = 17.8mm x 9.6mm)

IC2 = LM393P, DIP-8



K1,K2 = 2-way PCB screw terminal block, 0.3’’ pitch, 630V rated

K3 = 2-pin pinheader, vertical, 0.1’’ pitch

K4 = 5-pin pinheader, vertical, 0.1’’ pitch

8-way DIL socket, 0.1’’ pitch, 0.3’’ wide (optional for IC2)

PCB no. 180611-1 v1.0 (Elektor Store)

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