Farnell PDA3502A Dual-Channel Power Supply

An old-school linear supply with two outputs and needle meters, and it is on the bench for a reason. Op-amp circuits and audio stages need plus and minus at the same time: in tracking mode the second channel follows the first, and one knob gives a symmetrical ±12 or ±15 V. As a linear source it produces almost no switching noise, which shows when you look at weak signals on the scope.

The needle meters are for orientation. When the exact value matters, measure the output with a multimeter.

How to use

1. Switch on with the outputs off. Select INDEP or TRACK with the mode switch.
2. Current knobs to minimum, then set the voltage on each channel, or on the master in tracking mode. Raise the current limit only as far as the circuit needs.
3. For ±V check the wiring diagram in the manual: in tracking mode the channels are in series and the middle point becomes the common.
4. Connect the leads, check polarity on both channels, enable the output.
5. When done, switch the outputs off, remove the leads, switch the supply off.

Take care

• Red is plus, black is minus, the green terminal is earth. Two channels, twice the chances to mix them up.
• Do not connect the output to a live circuit or in parallel with another source.
• The supply gets warm in use; do not cover the vents.

Access

The supply is on the electronics bench in the hackspace room, so a plan with hackspace access is required. No induction is needed. The supply stays in the room.