I'm looking for a rotary potentiometer that comes with a momentary push switch.

I came across this Bourns PTR90 potentiometer with rotary switch and I'm wondering how does the rotary switch works? It says 50 degree for switch activation angle in the datasheet. Does it mean the switch will be on when the position of my knob is at 50 degree?

I also saw this Bourns PDB183 potentiometer with push-pull switch. Is this a momentary switch or if I press them, it will stuck in the push position unless I pull the switch?


  • \$\begingroup\$ the PTR90 is probably like a volume control of a radio that is also a power switch ... extreme counter clockwise rotation has the switch off ... turning clockwise causes the switch to turn on .... the max 50 degree switch activation makes sense if the pot range is 30 degrees to 330 degrees (300 degree range) ... switch activates at less than 20 degrees from begining of rotation ... it probably deactivates at lesser angle \$\endgroup\$
    – jsotola
    Commented Jun 1, 2021 at 22:04

1 Answer 1


For the Bourns PTR90 you are correct. It could be up to 50° of rotation before the switch will "toggle" to its alternate position and you won't be able to park it anywhere in between. So if used as a volume control, for example, you won't be able to set to a low volume. The 50° switch activation angle is 1/6 of the 300° potentiometer "mechanical angle" - the rotation range.

The PDB183 is listed as a "push-pull" so it will latch or stay put when pulled or pushed. The alternative would be a "momentary" type. These are common on rotary encoders for use as the select function but would have very little use in potentiometer applications.


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