Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

Reinventing potentiometer with rotary encoder

Normally potentiometer is a passive electronics part which changes resistance when knob is turned. Kuala decided to make his own by using microcontroller and rotary encoder. Since it is digitally controller, he also attached three 7 segment LED indicators to display its current value. Operation is simple – microcontroller reads rotary encoder steps and increases/decreases value which then can be sent to another host device through I/O interface. If you need real resistance value, it can bu used along with digitally controlled potentiometer (like MCP4551). With rotary encoder select there may be several devices chained. Continue reading

Simplistic DC motor speed controller

As you may know best way to control DC motor speed is to power it with PWM (Pulse Width Modulated) signal. Microcontroller is good at generating PWM signals so Andrian build one using Attiny13 microcontroller. His need was to control 7A 20Volt motor. For this he used n-mosfet IRF540N. To change PWM duty cycle he used Rotary encoder. As there were couple microcontroller pins left, he used them for LEDs to indicate MAX and MIN speed of motor. Important part of schematic is motor switching transistor. Using diode is necessary part as it takes care of inductive currents. Also there is a capacitor used in parallel of motor to reduce generated noise. So great small circuit to run small DC motors or use a general purpose dimmer for LED stripes. Continue reading