This is a variable voltage analog power supply based on the LM317 voltage regulator. The voltage is adjustable from 1.2 VDC to 25.5 VDC via a “VOLTS ADJ” potentiometer. There is also a “MAX ADJ” trim potentiometer that can be used to limit the maximum output voltage. The input is protected by an auto-reset fuse and also against reverse polarity.
The main output regulator is fan cooled allowing continuous operation at high current levels and high ambient conditions. The regulator has built-in thermal protection and current limiting. The maximum input voltage is 35 VDC and the maximum output load current is 1.5 Amps DC at any voltage.
A three digit green LED display functioning as a voltmeter is provided and is used to adjust the output voltage to a specific value. Display resolution is 0.1 VDC. Additionally, by pressing a pushbutton, the display will show the highest and lowest output voltage values that occurred while the power supply was in operation. This provides a simple way of monitoring the output voltage. A separate five volt regulator is used to power the display. A FREESCALE MC9S08QD4 MCU is used as an analog to digital converter and a FREESCALE MC14489 is used to drive the LED displays. A green LED is provided to monitor the five volt supply and another green LED is used to monitor MCU operation.
The PCB measures 3.0in by 6.0in and made of 0.032in glass epoxy.
PCB ASSEMBLY
PCB LAYOUT
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