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Is this switch available anywhere

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stuhagen

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I had a post over in Auto, but I now know more about how this switch works. It is approx. 14mm x 14mm square. It is about 25mm tall. It has 3 solder legs. The switch has little clicks as it rotates. It also rotates continuously. The center leg is ground. The 2 outer legs are N/O. When you rotate it in either direction it momentarily grounds out, or sends a brief ground pulse to the main head unit. That ground pulse turns "up" or "down" the speed of a fan blower. There are a total of 5 speeds.

I have bought 2 types of pulse switches, but because of there PWM square wave, the pulses are either too fast or it doesn't really send a momentary ground pulse. Basically it is a spring loaded momentary thing. I tested it by wiring 2 momentary switches and with a quick push the fan goes up with pushing the one button and the other button quick push lowers the speed.

I cannot find anything in Panasonic, Alps, or anything that fits the size and type of the one I have now. It is possible there is not such product out there. It is out of a 20 year old product.

Stu
 

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It's a special type of switch known as an encoder. You may have better luck searching for one of those. But, being 20 years old, you may not have any luck finding one with the exact same dimensions and pin arrangement. It looks similar to a Panasonic EVE series encoder.
 
with a little, OK lot of work on your part, you might be able to get something to work. This https://www.sparkfun.com/products/9117 is a 12 pulse grey code encoder. 12 is nonetheless better than 24 or 24 or 1024., but it;s not the signals you want.

If you combine it with the 402 here https://www.elmelectronics.com/ebench.html#RotaryDecoders you'd get awfully close.

If you divided the outputs by 2 which is easy to do with a Flip flop your even better,

One of the problems is I, or you would need to know the voltages "across the switch" when it's in the open position.

When you know the voltage, I have another test based on using a few diodes.

If you could reverse engineer anything around the switch, that would help. It could be pulled up through a resistor to +5, +12 or any voltage for that matter. That would help with the interfacing.

Three major parts at this point: encoder, encoder to UP & DOWN and probably a ULN2003. You'll need a 5V supply somewhere or need to be able to make one from whatever is available DC-DC converter.

It might be fun. Maybe not cheap and definitely not mechanical.
 
I was mistaken. The center leg is a constant 12v. The outer 2 legs go to the main board, and obviously is not a ground. It either goes into an open collector, or just passes a 12v
signal to raise/lower the fan. On the switch out of the board, reading from center leg to outer leg increases in resistance CW , and decreases in CCW. I am going by memory, but it is something like 9m rising to 30m in each click CW and 30m to 9m CCW by each click. But it reads this less than 1 second, then goes to open. The reading from the 2 outer legs is open.

Reading the same in the new decoder switch I got, it displays the same except it reads two levels of resistance in 1 click rotation. The one I just got goes something like this:

8m-28m-0, 11m-23m-0, 15m-17m-0, etc
 
I'm not sure what your describing at all with the 8m-28m-0 m is milli, M is MEG, m is a letter of the alphabet.

that out of the way, your lower/raise push button operation means you need UP and DOWN pulses. Your 12 V supply means something. It means you have a 12 V supply.

So, you have a switch; measure the voltage across the switch. You MIGHT be able to hold it in that position.

If you can make the UP/DOWN work with a 200 ohm resistor and open (about 300 Meg ohms) you can use an OPTO FET.
 
With only three connections, it almost certainly must be a quadrature encoder. That's the only way that you can determine direction of rotation with only a common connection and two switched outputs.
 
BobW said:
With only three connections, it almost certainly must be a quadrature encoder. That's the only way that you can determine direction of rotation with only a common connection and two switched outputs.

Not likely because of the following:

the OP said:
I tested it by wiring 2 momentary switches and with a quick push the fan goes up with pushing the one button and the other button quick push lowers the speed.
 
Possibly, but it depends on how the how the circuitry processes the quadrature signals. There are several different algorithms, and when you also take timing and contact bounce into account, almost anything can happen.
 
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