
The experimenter's pot is a solid state
potentiometer using Dallas semiconductor’s
DS1869
and National’s LM78L05 two electrolytic capacitor
two small push button switch and two optional Molex
connector. this project is very useful especially in
finding the right value of resistor in your
experiments, you can attach this circuit to your
next project that uses a pot or trimmer cause there
are three types of DS1869 these are:
- DS1869-10 which is 10K
- DS1869-50 a 50K version
- DS1869-100 the 100K version

As you can see, the circuit is powered from a 9V
power supply (actually any 9V power source will
work, as long as the current rating is not less than
25mA) stepped down to 5V by the LM78L05 IC and two
filter capacitor one for the input and one for the
output, the wiper arm’s position is stepped by
pressing SW2 for adding the resistance of wiper arm
to high terminal and SW1 for decreasing just like an
ordinary mechanical potentiometer adding the
resistance to high terminal decreases the resistance
to low terminal.
Parts List:
C1 10uF/16V Electrolytic capacitor
C2 0.01uF/50V Ceramic capacitor
U1 LM78L05
U2 DS1869 (see notes)
SW1,SW2 Small push button switch
Notes:
The maximum wiper current allowed through the DS1869
is only 1 milliamps. There are three types of DS1869
DS1869-10 use this chip if you want to make a 10K
version
DS1869-50 for a 50K version pot.
DS1869-100 for the 100K version

The [schematic] and the
[board] is drawn
using expresspcb, it is available for download you can etch your
own PCB using TTM (Toner Transfer Method) or you can order your boards
at http://www.expresspcb.com
Download
this circuit in ZIP