BearDodge67
Well-Known Member
A diode is like a check valve. power only goes one way,the direction the arrow points. Try to reverse it and it gets blocked. That's how they are designed. It's actually how you test it with a ohmmeter/circuit tester.. One way works, other doesn't.. good.. Neither work, bad.. Both work, bad. I tested enough of them on old submarine sonar systems to have it burned in my head.
To get back to the OP's question.. here's how I did a electric fan I pulled out of a fwd Ford in boneyard. The big connector at top was wired directly to the batter for both 12V and ground. The coiled blue wire went to a distribution block (you'll see later), that was fed from a 12 ignition switch source (think of this as your toggle switch). The blue wire provided power to the adjustable temperature probe. When it hit the temperature I wanted, 12V would get sent to the coil which would energize and connect the 12V from the battery to both fans via the fuse block on the housing. The gaggle of wires in the middle acted as a ground for the relay and both fans that went back to the battery. Worked great, later on I added a second relay and wired it to a idiot light temperature sender. One fan ran when it got warm, and second would engage when it got too hot.
This is an example of a MSD using a circuit breaker and a relay. The distribution block metioned above was fed from a 12V ignition switched source, soon as key went to RUN, it had power. This energized the relay, which had 12V fed directly from the battery, which went thru a circuit breaker and then the MSD.
This setup is long gone once I went to a MSD distributor, except for the distribution block, that feeds my ECU and the fuel pump as well as gauges.
To get back to the OP's question.. here's how I did a electric fan I pulled out of a fwd Ford in boneyard. The big connector at top was wired directly to the batter for both 12V and ground. The coiled blue wire went to a distribution block (you'll see later), that was fed from a 12 ignition switch source (think of this as your toggle switch). The blue wire provided power to the adjustable temperature probe. When it hit the temperature I wanted, 12V would get sent to the coil which would energize and connect the 12V from the battery to both fans via the fuse block on the housing. The gaggle of wires in the middle acted as a ground for the relay and both fans that went back to the battery. Worked great, later on I added a second relay and wired it to a idiot light temperature sender. One fan ran when it got warm, and second would engage when it got too hot.
This is an example of a MSD using a circuit breaker and a relay. The distribution block metioned above was fed from a 12V ignition switched source, soon as key went to RUN, it had power. This energized the relay, which had 12V fed directly from the battery, which went thru a circuit breaker and then the MSD.
This setup is long gone once I went to a MSD distributor, except for the distribution block, that feeds my ECU and the fuel pump as well as gauges.
