LM12 operational amplifier can output currents up to 10A. The LM12 in encapsulated in TO-3 with 4 pins, can support up to 800W and has enough internal protections to prevent slacks from over-currents or over-heating.
You can use LM12CL with 30 V maximum voltage or LM12C with 40V maximum.
The L1 coil has 40 turns 1mm copper, coiled over R4. If you use LM12CL it is recomended to have toroidal transformer 2 x 22V. The output must be between 7 and 12A. Filtering capacitors must have at least 20.000 uF.
LM12 must be mounted with screws on a big heatsink (=< 1.50 C/W) and electric isolated form the heatsink