This high-current version of MSD's Solid-State Relay Block, finished in black, replaces 4 standard relays and eliminates unsightly wiring. Each of the 4 independent channels can be activated using either power or ground and handles up to 35 amps of continuous current, for a combined 140 amps of power. It also supports Pulse Width Modulation, letting the output be controlled at up to 150 hertz with a 50-90% duty cycle — useful for controlling electric fans, water pumps, nitrous solenoids, auxiliary lighting, and similar accessories.
Specifications:
- Part Type: Multi-Purpose Relay
- Color: Black
- Channel Count: 4
- Amperage Rating: 35A continuous per channel (100A for 8 seconds)
- Combined Rating: 140A continuous
- Supply Voltage: 7V to 20V
- PWM: Up to 150 Hz, 50-90% duty cycle
- Part Number: 75643-HC
Recommended wire gauge: 2 AWG for main battery input, 8 AWG for channel outputs, 18-22 AWG for 12V/ground activation wires; channels can be paralleled for loads exceeding a single 35A channel.
FAQ
What's different about the 75643-HC versus the 7564-HC?
They're functionally identical 35A-per-channel, PWM-capable relay blocks; the 75643-HC is finished in black while the 7564-HC is red.
What is the combined amperage rating?
Up to 140 amps continuous across all 4 channels, with each channel rated to 35 amps continuous or 100 amps for 8 seconds.
Does it support PWM control?
Yes, up to 150 hertz with a 50-90% duty cycle.
What is the recommended wire gauge?
2 AWG for the main battery input, 8 AWG for channel outputs, and 18-22 AWG for 12V/ground activation wires.
