Hi,

I have attached an schematic which I took from a board. I followed the board lines and that's what I got.

That circuit is used to control an incline motor those that you can find in a treadmill.

I'm having hard time trying to understand that circuit. I have read information on the web, but still got my wires crossed. Maybe I'm not understanding well triacs and opto triacs with zero crossing circuit.

Could anyone help me understand the principle of this circuit? How is the transition between the inductors? As it is from a treadmill, the motor goes up and down depending on the inductor energized.

I would appreciate your comments.

 

You did a good job decoding and transcribing the circuit.

The motor has two windings and a capacitor, which is used to phase-shift the current through the opposite winding.
This phase-shift creates a rotating magnetic field which causes the rotor to spin.
The relay reverses the phase arrangement, and hence, the direction of rotation.


The opto-coupler and external triac just form an AC power switch that controls the whole circuit.
Optical isolation provides a safety barrier between high and low voltage circuits.

The zero crossing action minimizes switching noise by preventing the triac from turning on when the voltage across the terminals is greater than some relatively low voltage (not actually zero, because it would not switch on) - all switching occurs when the AC line voltage is low.

 

You did a good job decoding and transcribing the circuit.

The motor has two windings and a capacitor, which is used to phase-shift the current through the opposite winding.
This phase-shift creates a rotating magnetic field which causes the rotor to spin.
The relay reverses the phase arrangement, and hence, the direction of rotation.


The opto-coupler and external triac just form an AC power switch that controls the whole circuit.
Optical isolation provides a safety barrier between high and low voltage circuits.

The zero crossing action minimizes switching noise by preventing the triac from turning on when the voltage across the terminals is greater than some relatively low voltage (not actually zero, because it would not switch on) - all switching occurs when the AC line voltage is low.

I attach another circuit which I found on the web. It uses two triacs, but it seems less complicated than the one previously posted. What are the advantages and disadvantages of both circuits?