On 10/11/2017 20:01, JoeJoe wrote:
See he

http://tinypic.com/r/qsqp1z/9

Question is:Â* why would you want to put a variable resistor between Z
and Y, and not a fixed value one?

I could do this in my sleep years ago, honest...

Well - if the component between Z and X is a thermistor
(temperature-dependent resistor), the variable resistor between Y and Z
lets you set the temperature at which the LED lights..... (I think).