temperature turn on for fans

resquchas wrote: in your application external fans are a good idea if you are going to confine the amp in that enviroment. push/pull or any configuration is acceptable as long as you account for laminar airflow. bay far the easiest way to do this is to just wire up the fans to run with the amp on. try COOLERGUYS.com. they specialize in stuff like this. let me know what you decide and/or come up with. the wiring should be pretty straightforward. but i can help if needed.

Thank you! How can I wire the breaker below posted by oldspark to the relay?

oldspark wrote: I call the temp switches Klixons, but that is a trade name. They are typically ~$5 or less. EG - http://www.jaycar.com.au/productView.asp?ID=ST3821 - use NO type.

Perfect oldspark! How do I wire this to the relay?

ok i like old sparks source. here goes the wiring since it is a normally closed circuit do it like this. 85-    12v+ from head unit blue remote 86-    ground 87a- 87-    12v+ 30-    12v+ out to relay number2 pin 85 #2 85-    from relay #1 pin 30 86-    ground through st3821 87a-   12v+ out to fan/fans 87- 30-    12v+ this will do what you want. IF the headunit is on and the temp is low then no fan, when the st3821 gets hot and breaks ground then pin 87a gets into its resting circuit and will turn on your fans. use diodes to protect across coils.The RIGHT way is the ONLY way.

Thank you very much. I understand 85% of this. I am using st3821 as a ground circuit then right? When it is open the relay does not have ground and when it is closed the relay has ground. Right? One terminal on st3821 goes to pin 86 on relay #2 and the other terminal goes to ground, right? I was also going to use pin 30 from relay #1 to a remote turn on distribution strip for my other amp and proccesor, is that ok? How do I wire diodes across coils? I have no idea about this.

you can use relay#1 pin 30 to power up to 30 amps worth of stuff if you have a 30amp relay so no problem. the 12 volt wire into pin 87 should be fused if you STEAL it off of , like your amplifier main power wire through distribution block.ANYTIME you change to a smaller wire guage then you must protect that new section of wire with proper fuse. if 60amp fuse and 4 gauge wire goes to amp then you can not just TAP into that, with like a 12 gauge wire because it would still be on the 60amp fuse....BAD. you will not draw much with these fans but all circuits need to be protected. you have got the st3821 wiring correct, its just in the ground path to cut the relay off and on as temperature dictates. diodes across the coil will prevent voltage spikes, potenetially bad ones, sometimes you hear them as pops through speakers. can damage stuff easily. cathode side of 1n4004 goes to the side of coil with positive so that at REST no current will flow, this is called a reversve bised diode clamp. cathode side has the stripe.The RIGHT way is the ONLY way.

Thank you. I do not understand "diodes across a coil". How do I wire that? I understand the side with the stripe is a cathode and the other side is an anode but that is it. What pins on the relay do I wire the cathode to? 87 on both relays? Thank you very much for your help!

Ok I did some more research. On relay #1 I solder the cathode to 87 and the anode to 85. On relay #2 I solder the cathode to 85 and the anode to 86. Is this correct?

diode only needs to be across the coil. this is going to be pins 85, and 86. cathode is toward the positive. relay 1 and 2 get same treatment.The RIGHT way is the ONLY way.

I got it! Pin 30 relay #2 gets the same +12v battery as pin 87 relay#1? I am going to draw up a schematic this weekend for your approval. Thank you very much for guiding me through this I really appreciate it!

when you draw it up, on relay number 2 change pin 87a and pin 30. the reason for this is when the relay is activated it will then have nothing "live on pin 87" if you insulate or use a relay pigtail then no issue really but that way no empty terminals are ever sitting with 12v waiting to touch something.so...... 85-    12v+ from head unit blue remote CATHODE 86-    ground            ANODE 87a- 87-    12v+ 30-    12v+ out to relay number2 pin 85 #2 85-    from relay #1 pin 30              CATHODE 86-    ground through st3821             ANODE 87a-   12v+ 87- 30-    12v+ out to fans/fans The RIGHT way is the ONLY way.

Got it. I included a small diagram of my electrical set up to better understand. I have a DC Power 270XP alt, D3400 starting battery and D3400 auxiliary battery in trunk. Relay I planned on using Dual relay socket Diodes Electrical overview [/IMG] Relay wiring [/IMG] Does everything look good? Correct fuse ratings? Thanks!!!!!!