second attempt triac

Ok... I found this circuit that controls the phase of an ac light or dimmer using an opto-isolator.... I attached it... but I don't know if it's viewable... here's the link: https://www.electro-tech-online.com/custompdfs/2003/07/AN-3006-1.pdf (figure 3)

I just had a few questions I was hoping somebody could answer...

1. Does VR1 control the speed of the motor? If not, what does?

2. Ok... is there any way to send a control signal into this thing as well? What I mean is this circuit can control the speed of the motor, but can I have my microcontroller decide whether or not the motor is on or off? Does this make sense? I want to make my microcontroller decide whether the motor is on or off, and I want the VR1 to decide the speed of the motor if it's on...

any help would be greatly appreciated

Seems to me that you could either control pin 4 of the 555 or put a transistor in series with the emitter of Q1 and control that transistor.

Ron

excellent... thanks for the idea... I think I'll try and do the 555 reset thing...While we're on the subject of Q1, I can't seem to find that part or datasheet anywhere... do you have any ideas of what I could substitute it with?

I couldn't find MPSA40 data either, but I looked at the specs for the H11L1, which drives Q1. You can use almost anything that qualifies as an NPN. I would use a 2N3904.

Ron

thanks... I'll try that