This 12V power supply circuit will provide a 12V regulated output with a maximum output current up to 3 amperes.
This 12V power supply circuit use the CA3085 IC voltage regulator with features like: good load and line regulation, output current up to 100mA (which can be increased to several amperes with additional pass transistors), output short-circuit protection, and lower input voltage.
A low power dissipation is achieved by driving external series-pass transistor 2N4241 (T1) from pin 2 of CA3085. Normal output pin 8 is returned to ground via diodes D3 and D4 to ensure error amplification operation in the linear region.
Ripple rejection is approximately 50 dB on no load and 35 dB on full load.
CA3085 can dissipate up to 650mW power in free air, without any heat sink.
A 2x2x2.5cm aluminium heat sink helps the circuit in dissipating heat without exceeding maximum device ratings.
This circuit is specially designed for use with 2m handheld rigs with linear power amplifier and CB portable QRP rigs.