powering three electric fans
Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=128029
Printed Date: May 04, 2024 at 8:18 PM
Topic: powering three electric fans
Posted By: paddlenbike
Subject: powering three electric fans
Date Posted: July 25, 2011 at 10:39 AM
Hi,
I could use some assistance with a wiring project I have before me. I have a rotary switch with off-lo-med-hi settings and I want to power 3 separate fans in this orientation: "low" on the switch turns on one fan, "med" on the switch runs two of the fans and "hi" runs all three fans. This is a 12V DC system on a boat.
I am familiar with how to use relays but this project has me stumped. Any replies are greatly appreciated.
Replies:
Posted By: i am an idiot
Date Posted: July 25, 2011 at 3:24 PM
Do you have a rotary switch? This will be an easy task with the switch and a few diodes and the 3 relays. I can draw you a diagram tonight.
Posted By: dualsport
Date Posted: July 26, 2011 at 6:22 AM
Yeah, pretty simple with the rotary switch and a couple diodes, just wire the relays to each switch position, and add a couple of diode connections from switch terminal HI to MED, and from MED to LO.
Whenever the switch is a certain speed, the diodes will feed the next lower speed relay.
MED will feed the MED directly, and feed LO through the diode.
HI will feed HI directly, and feed MED through the second diode, which in turn feeds LO through the first.
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