If you fire the SCR at 80 degrees on a normal sine wave you will get everything *greater* than 80V rather than everything less.
The normal approach is to trigger a one shot with the zero cross of the AC and use it's output to trigger the SCR. If the load is pure resistive it works. If the load is reactive, you may have some problems.
The normal approach is to trigger a one shot with the zero cross of the AC and use it's output to trigger the SCR. If the load is pure resistive it works. If the load is reactive, you may have some problems.