PS23023 Velleman Power Supply

I did not find any Kicad design files for the PS23023 from Velleman online, so I created my own from the manufacturer’s manual. The design of this power supply seems to be fairly common, their are many clones of it available.

Manufacturer’s manual: Here

Original Schematic

Master

Ref: AQF7.820.7120

Specifications:

• Dual output: 0-30V / 0-3A
• Additional 5V / 3A output

I used KiCad to redraw the schematic from the manual.

Transformer

All voltages are measured without load.

Primary       Secondary
230v ---|   |--- 18v    (orange)
        |   |           (Aux winding)
        |   |--- 0v     (red)
        |   |
        |   |--- -18v   (white)
        |
        |   |--- 39v    tap 1 (green)
        |   |
        |   |--- 31v    tap 2 (yellow)
        |   |
        |   |--- 16v    tap 3 (orange)
        |   |
0v   ---|   |--- 0v     tap 4 (red)

Tap Switching

Here is the switching diagram of the transformer:

We can see that voltages are not equally spaced.

Tuning

The power supply can be tuned by adjusting the following components:

• RP2: Adjusts the maximum output voltage range.

• RP1: Adjusts the maximum output current range.

• RP9: Adjusts the offset current, to ensure 0A at minimum setting.

Gallery

Notes

Some components may vary depending on the version of the power supply. For example, in my supply U18, U17, R17 and R19 are not populated. Also it shows some unpopulated components for an additional relay that is not present in my version.

Slave

Ref: AQF7.820.7120

Slave is identical to master, except the control potentiometers are different because they are routed through Serial/Parallel/Independent switches on the front panel board.

5V 3A Output

Ref: AQF7.820.775

Specifications:

• Fixed 5V output
• Max current: 3A

This supply is based on the LM723 voltage regulator IC with a single 2n3055 ballast.

It uses a middle tap transformer and an auxiliary winding to power the LM723. The general design is weird, but it can be related to my own PS23023 power supply, as the serigraphy on the PCB for wires is a bit confusing.

Transformer

All voltages are measured without load.

Primary       Secondary
230v ---|   |--- XXXv   (green) (not measured yet)
        |   |           (Aux winding)
        |   |--- 0v     (green)
        |
        |   |--- 12v    (blue)
        |   |
        |   |--- 0v     (black)
        |   |
0v   ---|   |--- -12v   (blue)

Tuning

The power supply can be tuned by adjusting the following components:

• RP1: Adjusts the maximum output current.

• RP2: Adjusts the output voltage.

Gallery

Charge Pump

Ref: AQF7.820.7173

Specifications:

• x4 9V “isolated” output
• input voltage: 12V DC

This is the charge pump schematic used to supply all lcd voltmeters/ammeter modules with 4 “isolated 9V supplies”.

Switching circuit use only CD4049UBE and the frequency is set by R1 and C1. You can adjust them to change the frequency if needed. I measured around 40kHz with the given values.

Gallery

Repair and Modification