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9-Channel Relay Switcher Board

with local and remote control

9-Channel Relay Switcher Board
Many situations require switching on or off multiple devices individually from a central place like a control room. Installing a switch for every individual device on a control desk looks like an easy solution but does not allow for remote- or computer control. The circuit presented here adds these features.
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Download the BOM list
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


default: 5%, 0.25W

R1 = 330Ω
R2,R7 = 4.7kΩ
R3,R4 = 1kΩ
R5 = 4.7Ω
R6 = 10Ω
RN1 = 10kΩ, 8-way SIL network
P1 = 10kΩ preset


C1 = 220µF, 50V
C2,C3,C5,C6,C7,C8 = 100nF
C4 = 100µF, 50V


D1,D3 = 1N4007
D2 = BAT43
IC1 = MC7805
IC2 = PIC18F45K22-E/P, programmed
IC3 = ULN2803A
T1,T2 = BC547
LED1 = red, 3mm


K1 = barrel jack, 1.95mm centre pin
K2 = 6-pin pinheader, 0.1'' pitch
K3-K11 = 3-way terminal block, 3.5mm pitch
LCD1 = LCD, 4x20, 5V with backlight w. 14-pin pinheader + 14-way pinheader socket
RE1-RE9 = Relay G5LE-1 12VDC coil, or equivalent
S1-S9 = Tactile switch, 12mm, B3F-4000 or equivalent
BoB1 = FT232R USB/Serial Bridge/BOB, Elektor Store # 110553

DIP socket, 40 contacts

DIP socket, 18 contacts

HS1 = TO-220-style heatsink

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