Triac Circuit with Voltage Divider.

[Bskitter]

Hello People.

I have a question here, but first a little background story. I have an SMD station that lost its magic smoke a while back. So I made a little project to fix it. I am basically redoing all the electronics inside.

I have basically complete the interface for it (The Temperature display and Pot readings) I am now doing the power control circuit for the Air Pump and Element Control...

So here is the question. On the old circuit there was a Bridge Rectifier on the output of the triac going to the pump. After a lot of searching and asking my Professors at the university I found out that this Rectifier acts as voltage divider for the inductive load.

Below is the schematic.



Now here is the new circuit ill be using to control the Pump.



I am gonna use the Microcontroller to control the speed of the motor.

Now. How do i connect the bridge rectifier to the Optocoupled circuit ?

I am thinking of something like this.



Any suggestions would be appreciated 

Byron

[NiHaoMike]

The arrangement with the diodes improves control at low levels. It is not needed with a SSR.
http://techno-fandom.org/~hobbit/lighting/dimmer.html

[Benta]

As far as I can see, the bridge rectifier in your first schematic doesn't do anything at all. Have you oriented it correctly?

[Andy Watson]

As far as I can see, the bridge rectifier in your first schematic doesn't do anything at all. Have you oriented it correctly?

It removes a "hysteresis"  effect at low power settings by returning the timing capacitor voltage to zero each new half-cycle. The link that NiHaoMike provided explains the problem.