Is this an encoder?

[stuhagen]

I am trying to find a replacement for a Alps unit out of a 30 year old Japanese car. I have tried some but most do not do what this one did. It is a fan speed dial, Rotate i direction is sends descending resistance. Rotate the other direction it sends increasing resistance. This tells the ECU to either increase the fan speed or decrease. I have found a Alps that works but it is different (4-pin) and a bit too large. Here are pictures of it and how it works. I am not sure if I am looking for the correct piece. Is this called an "Encoder"?
You can see in the schematic picture that it is a spring loaded directional momentary switch.

 

[Diver300]

If the knob is turned with the car turned off, does that affect the fan speed when the car is turned on? Does the knob have end stops?

If the answer to either of those is "yes", it is most likely a potentiometer. If no, it's most likely an encoder.

 

[stuhagen]

No for both. Car needs to be on

 

[Nigel Goodwin]

It looks like a standard quadrature encoder, and Alps are one of the big manufacturers of them.

A simple google finds 134 different ones listed at Farnell

 

[stuhagen]

It looks like a standard quadrature encoder, and Alps are one of the big manufacturers of them.

A simple google finds 134 different ones listed at Farnell

I agree but man...which one do I choose? I can narrow it down as no switch needed...Detent maybe 12-18, shaft type (Slotted) which may reduce it down to a few(er) I need to research what is a quadrature vs not...

 

[rjenkinsgb]

shaft type (Slotted)

That looks to be a flatted or "D" shaft, not slotted?

 

[stuhagen]

That looks to be a flatted or "D" shaft, not slotted?

Yes, sorry it is that...