Parametric Spool with magnetic brake

thingiverse

Parametric spool with "locking encoder" on the side to be used with a spring-supported electromagnet. This prevents the spool/mottor from freewheeling on powerfailures. Magnets need to be driven by PWM to prevent them from overheating: I did it with the LEDc lib, to be able to control the PWM-frequency. WHY? Mosfet overheated at high PWN due to too many on/off cycles. might also be caused by my bad electronics design though ;-) // PWM for magnets int freq = 20000; int pwmChannel = 0; int resolution = 8; magnet unlock sequence: ledcWrite(pwmChannel, 255); // full power to unlock the solenoids delay(1000); Serial.println("PWM 40"); ledcWrite(pwmChannel, 40); // low power to keep the solenoids in unlocked position delay(500);