need design help

Thread Starter

thetank

Joined Feb 13, 2007
14
so I want to build a fan bus for my computer. I want it to have a 3 position DPDT switch(on-off-on). with the switch in the up position the fan gets 12v, switch down, 5v. with the switch in the center position I want to control fan voltage with a variable resister from 0v to 12v. now here’s the kicker, i want LEDs above and below the switch, hooked up to a temp probe. when its over a set(adjustable) temp the red LED blinks, under a different temp, the blue LED blinks. I know next to nothing when it comes to circuit design, can anyone help? links to DIY projects would be awesome. Thanx.




Tank R.
 

Thread Starter

thetank

Joined Feb 13, 2007
14
UPDATE:

so i figure im gonna use 556 timers, where above temp will turn on side a and below temp will turn on side b. how do i use a transistor(?) to do thatand still have adjustability? the LEDs have a reed relay N.C. So when the 556 timer does its thing it opens and closes the circuit to the LEDs at about 1Hz. As for the fans, i get how to get them to run at 12v or 5v through a 3 position switch, but not how to have the center position be the voltage control. when i have a few schimatics done i'll post them.
 

Thread Starter

thetank

Joined Feb 13, 2007
14


U1, and U2 are transisters(?) that tells the 556 timer(astable) to do its thing when a adjustible tempature is reached, U1 for over X°F, U2 under X°F. the thermocouple will be a K-type. the relay befor the LED is a N.C. type, when the 556 time sends its square wave it blinks the led. but i still need to know what part# U1 and U2 should be. and what U3 should be to trigger the relay, if needed. also should i run the whole thing on 5v or 12v?





does anyone know where i can get a toggel switch to make this circuit happen?
 

thingmaker3

Joined May 16, 2005
5,084
I think your avatar may be putting folk off.

Also, running a computer fan at lower than design speed is a risky idea. No one here wants to be responsible for a fried motherboard.

Better to simply wear headphones.;)
 

Thread Starter

thetank

Joined Feb 13, 2007
14
for what im doing theres no(real) problem with hurting the mobo. all im doing is controlling intake and exhaust fans. the CPU fan is still controlled by the mobo.



its a smily pooping itself to death. whats so wrong with that?
 
Top