Noise Source PSU

This simple unit is designed to switch a 28v (or 12v) supply for a Noise Source and be controlled by the Portsdown NF Meter. The input switching signal is 0v for the "off" state and 3.3v for the "on" state.

The simple schematic is here

The Bill of Materials is here.

Error on the First Batch of PCBs

The Initial batch of PCBs for the Noise source power supply had one error. The Vout and Adj pins on the current-limiting LM317T (U2) were reversed. The unit functions if assembled with the error, but the current limit will not work correctly. To correct the error, the PCB should be modified as shown below, or pins 1 and 2 on U2 should be swapped.