Variable Parameters like voltage, current can be obtained by using a Digital Potentiometer. Microcontrollers or Counters operate FET CMOS Analog Switches. The switches configure resistor networks to adjust circuit performance. It could be a Speed Control of a Motor or Brightness of a Lamp. Volume controls and Tuners also can use this.
Description. - In this Circuit, digital potentiometer, connect pushbutton switches to fast and slow with one end to +7.5V, when you hold the button down the analog voltage will ramp up-down, fast or slow, this will enable you to make a digitally controlled millivolt source or power supply.
Digital Potentiometer - del50003
Here is a Millivolt Source i built for Calibration in the early days. It uses only CMOS Digital and Mixed Chips from Intersil and CD40xx Series.
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