Anyone have any suggestions of how to multiply a resistance range. How to change 0- 10 k ohm resistance to 0-1000 K ohm resistance. Putting 100 variable resistors in series seems an expensive approach. Is there a circuit that can do the same thing?
Note: It looks like my range of timing is between about 13,000,000 microseconds and 90 microseconds. Since at some point above the top end 13,000,000 (us) the Photon breaks and shows a solid green LED, and at the bottom end 90 (us) seems to be the duration of one loop.
I am thinking about 3 ways to auto adjust the charging resistance to detect a greater range of unknown capacitors.
If I charge the capacitor using PWM, I can then adjust the power sent to the unknown capacitor which should allow me to charge a greater range of capacitors
If I could find a digital potentiometer board it would be easy to auto adjust the charging resistance and auto adjust the calibration constant. Unfortunately I can’t seem to find any digital potentiometer boards that have a large resistance range. Here is something with a 0 - 10 K ohm range. http://www.uctronics.com/x9c103s-digital-potentiometer-module-3-5v-for-arduino.html?feedback=1
Manually adjust the charging resistance using a potentiometer with analog sensor such as the link below unfortunately this is also only in the 0-10 K ohm range.