• Output: 9v & 12v DC @ 1A
• Input: 18v AC max. or 24v DC max.
• LED on indicators
• PC board construction
• Difficulty Level: Intermediate
The circuit is a standard step-down, full-wave bridge-rectified (3-Amp), capacitor-filtered, with two independent, discreet, linear voltage regulators. It uses two 78XX voltage regulator ICs which are rated for over 1 amp each. It also has an LED for each voltage regulator to indicate a valid output voltage. Each output voltage is totally independent of the other.
The circuit can accept low-voltage AC or DC inputs. The maximum AC input voltage is 18VAC and the maximum DC input voltage is 24VDC (Do not connect this directly to the 120VAC power line). The bridge rectifier can be bypassed if you are connecting DC to the inputs. A heatsink may be required if the voltage regulator gets very hot during normal use. It uses 2-pin screw terminals for the input and the two outputs.
The PCB is 2.6″ x 1.9″ and is made of .062″, FR-4 epoxy-glass. It is double-sided with plated-thru-holes, 1-ounce copper, and silkscreen on the topside. It has 4 mounting holes. The circuit is 1.1″ high from the bottom of the PCB to the top of the filter cap.