(3 Reviews)
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While this is being advertised as a dual 100k potentiometer the two potentiometers are not completely isolated. They share a common pin. Also, it is not perfectly linear. The B-4 rating is the 2nd to the least accurate of the linear series of potentiometers.
Also, there are two pins that I have no idea how they are internally connected but they share resistances with the two 100k potentiometers. These are pins 1 and 4. Pin 8 is a no connect.
Special note on resistance between pins 1 to 7 and pins 4 to 5. These pins are approximately 50k at full ccw and full cw however they reduce in resistance as you turn the shaft and pass through 0 ohms near the center position.
Other observations:
The motor draws approximately 30 mA during rotation and approximately 40 mA when stalled against the end of travel.
The gear box is a little nosier than I expected but not too bad. It takes approximately 6 seconds to travel one full rotation.
As viewed from the bottom with the knob forward. Pin 1 on the left:
R1 is pin 1 to pin 6 with the wiper on pin 7
R2 is pin 2 to pin 6 with the wiper on pin 5
Pin 8 is no connect
Pin 1 to pin 4 is approximately 95.4k
Resistance between pin 1 to other pins vary as does pin 4 to other pins. I could not include a table because this review format won't allow it.
Overall this is a good deal for the price and having a common pin between the two pots is not a big deal if you intend to use it as a volume control since most stereo outputs share a common ground. I knocked off one star for the poor linearity of the B-4 series. If you want to see charts for the different series you can go to this Bourns site:
https://www.potentiometers.com/pdf/prm16.pdf
The comments from Westlake Village were helpful in figuring out the pinouts of this pot.
However, I think there are some typos. The following are connections I observed:
As viewed from the bottom with the shaft towards you. Pin 1 on the left:
R1 is pin 2 to pin 6 with the wiper on pin 7
R2 is pin 3 to pin 6 with the wiper on pin 5
Pin 1 is a center tap on R1
Pin 4 is a center tap on R2
POT-1
1--------------- |
2-------/\/\/\/\/\/\/\/\---------6
7---------^
POT-2
4--------------- |
2-------/\/\/\/\/\/\/\/\---------6
5---------^
I believe these are older ALPs pots, but I did find something similar.
searched aliexpress for Z PRM 100KB-4
https://www.aliexpress.com/item/32853199257.html
https://ae01.alicdn.com/kf/HTB1a4CJoRTH8KJjy0Fiq6ARsXXav.jpg
I verified the pin connections on my parts to match column 4 shown in jpg url above. My pots are both 91K. Can't comment on linearity or other aspects.
| 100 + | $0.35 each |
| 1000 + | $0.25 each |
| 2000 + | $0.20 each |
| 100 + | $0.35 each |
| 10 + | $0.65 each |
