Variable pwm and vco

Red led shows the off time and the green is on time of the (pulse width modulator) white light simulate the load. PWM exist on pins 2,6,7 & the (voltage control oscillator) VCO is between pin 5 and ground. PWM adjust the on and off time duration of the digital pulse not meant to change the frequency much or at all. VCO change's the operating frequency cycles per second of the circuit not exclusive to the duration of the pulse. Note the higher the frequency the more current is delivered to the load, similar to the longer pulse width. Note ' the inverse is also true, lower frequency is the same as a short pulse width bearing in mind that the load is not frequency dependent. Lighting is normally tolerant of changes in frequency where motors and transformer are not as tolerant of changes. The charge to the iron core material used to create the magnetic fields can store charge in the form of heat from emf of work done and requires a percentage of off time to operate stable and sink the heat properly in core material used. Motors are ok with a frequency below the max design of the device but the voltage must remain constant. Lighting can have a variable voltage / frequency / current below max design current. Moral of the story is, use the circuit at your own risk and study your load requirements before application.

published 8 years ago