Article
A Zero Current Switch for Inductive Loads
Relays or contactors are often used to switch AC-powered inductive loads such as motors, valves or electro magnets. When the device is switched off, an arc can form across the relay contacts as they open. This leads to premature relay failure if measures are not taken to suppress the spark.
Materials
Gerber file
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PCB
Component list
Resistors
R1 = 100 Ohm
R2 = 2.2kOhm
R3,R4 = 47kOhm
R5 = 82kOhm 1%, 0.6W 350V (Vishay MRS25000C8202FCTOO)
R6 = 220Ohm
R7 = 180Ohm
R8 = 68Ohm
R9 = 22kOhm
Capacitors
C1,C3 = 10µF 100V 20%, pitch 2.5mm, diam. 6.3mm
C2 = 10µF 63V, axial, 10 x 4.5mm
Semiconductors
D1,D2 = 1N4004
D3 = 1N4007
D4 = BZX79-C13 (13V 05W)
B1 = WO6M, 600V 1.5A
T1 = IRG4BC3OKDPbF
T2..T5 = BC546A
IC1 = PC817 (see text)
Miscellaneous
PCB # 100270
R1 = 100 Ohm
R2 = 2.2kOhm
R3,R4 = 47kOhm
R5 = 82kOhm 1%, 0.6W 350V (Vishay MRS25000C8202FCTOO)
R6 = 220Ohm
R7 = 180Ohm
R8 = 68Ohm
R9 = 22kOhm
Capacitors
C1,C3 = 10µF 100V 20%, pitch 2.5mm, diam. 6.3mm
C2 = 10µF 63V, axial, 10 x 4.5mm
Semiconductors
D1,D2 = 1N4004
D3 = 1N4007
D4 = BZX79-C13 (13V 05W)
B1 = WO6M, 600V 1.5A
T1 = IRG4BC3OKDPbF
T2..T5 = BC546A
IC1 = PC817 (see text)
Miscellaneous
PCB # 100270
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