I want to control the speed of a 100watts dc motor using a full wave rectifier with scr. now i have a triggering circuit that is generating 12v pulses can i give these pulses to the thyristor gate to cathode.
and what type of thyristor rating i can choose plss any one suggest me

 

Look at the Littlefuse line, they should cover anything you would need.
You would need at least a 10amp rated.
http://www.digikey.ca/product-search/en?pv69=80&pv16=1683&FV=fff40015%2Cfff80083&k=littlefuse+scr&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25
You can also put two SCR's in the bridge for full wave control.
Another way is to use a Triac before the regular bridge followed by the motor.
Max.

 

No you should not connect your 12 volt control voltage directly to the SCR gate. You should instead use a isolated SCR driver. See the link for ideas https://www.google.com/search?q=scr+opto+isolator

 

thank you , for isolation iam going to use a pulse transformer, but i dont know the rating of it. can you please tel me.