ac/dc converters

hi everybody
I am new here. I started my new job last week in a ac/dc converters manufacturer company. I need any information about operational amplifier circuits that control the gate of S.C.R. I hope to be very usefull for you all.

We could be more helpful with more specific information.

o.k i´ll try to be more specific ac/dc converters control the speed os dc engines. The main component is a S.C.R wich its gate receive controlled pulses of a circuit based on a oscilator. The main purpose these circuits involving operacional amplifiers is increase or decrease the voltage on engines when the load requests more current, and also to limit the current on the load respecting the engine limits.
What i need is circuits with operacional amplifiers that do this function. i have searched in vain on web
Sorry for my bad english. I am very thankfull for your interest in my topic

You can't find it because no one does that. An SCR stays on once it is turned on, until the current thru it falls to a low value. Some applications use two SCRs, one to operate the load and another to turn it off. But it would be much simpler to use an FET. There must be lots of information on the web about motor speed control and PWM circuits.

O.K thank you very much for your interest.