Need help wiring a stir plate

I have a 25 ohm rheostat, an illuminated rocker switch, and a computer fan i need help wiring these up correctly. the rheostat is the standard 3 prong one from radioshack, but the rocker switch is a illuminated one from radioshack so it has 2 prongs then a little box with 2 wires coming out of it for the lights. I have no clue how to wire this thing up.. I was hoping someone would be able to help.


http://www.radioshack.com/product/index.jsp?productId=3125352#
(thick is the switch, you cant see it in the picture, but there are 2 prongs on the back of the switch in between the wires.)

TIA

What kind of computer fan are you using? 120V AC or 12V DC?

FWIW, that switch is advertised as being for AC. However, a few reviewers indicate that it can be modified for use with DC.

12V DC... I think i have it wired incorrectly still because the switch works it turns the fan on and off it just doesnt emit any light as it should, also my rheostat doesnt slow the fan down or speed it up any, it just stays at a constant speed

LOL! From the linked site:

"For those who aren't using the light because you want to use it with 12VDC and not 120VAC simply remove the black box and put a 220Ohm resister on the red wire and connect it to 12VDC. Put black to ground. Works just fine with 12VDC. And it's bright too!"

Cheers!

Would someone be willing to draw a diagram on how to wire this thing. Im clueless

Here is a quick try at a diagram. You didn't indicate what posted diagram you were using, so if this diagram doesn't match lmk. In addition, I am only guessing at what connections are present on the switch as I didn't find any diagrams. Two blades for the switch and the red and black leads from the little black box. The photo appears to have a red wire loop that I'm not sure of, maybe a jumper for a second LED? Cut the black box off, as it is not needed for DC-only operation. The center leg of the rheostat should be jumpered to one of the outside legs. Which outside leg depends on whether you desire clockwise= increasing rpm or counter-clockwise. The 270ohms is not that critical and increasing the value will provide less LED current and lower brightness. The resistor establishes the current drawn through the LED. The voltage polarity across the LED is important.

^ Looks right to me, wrt to getting the LED and fan to work with the switch.
And the current limiting resistor is definitely in the ball park, I wouldn't go too much smaller to start out as a cooked LED inside the switch will make someone sad

The 25 ohm pot is the sketchy part, but controlling any motor with a pot usually is. It'll probably work, at least for awhile...

Cheers!

day_trippr said:

^ Looks right to me, wrt to getting the LED and fan to work with the switch.
And the current limiting resistor is definitely in the ball park, I wouldn't go too much smaller to start out as a cooked LED inside the switch will make someone sad

The 25 ohm pot is the sketchy part, but controlling any motor with a pot usually is. It'll probably work, at least for awhile...

Cheers!

Click to expand...

Thanks for reveiwing. Yes, a higher value would protect the LED. I simply used a value that was posted in the radio shack reviews. I don't use this type of circuit on my stirplate. I prefer to have the control provided by a voltage regulator circuit, designed with max/min voltages equivalent to the max/min fan working voltages.