Power Build Instructions

Congratulations! You’re a few simple steps away from owning a great little module that will serve you for years and that you’ll have the satisfaction of having built yourself.

Building this project takes about half an hour if you’ve done some DIY electronics before, complete beginners should expect to take a little longer. The instructions assume that you can identify components, solder and do simple voltage and continuity tests with a multi-meter. There are lots of resources available to help you learn these skills – just hit Google or YouTube and you’ll soon be ready to start!

But before you do… we highly recommend that you

  • Take the time to read through this guide a couple of times
  • Check your parts against the Bill of Materials at the bottom of this page to ensure that you have everything that you need

Enjoy building your Power module, we hope you make great music with it!


To complete this build you will need

  • Soldering iron
  • Solder
  • Wire cutters
  • A voltmeter or multimeter
  • 2mm allen key (all of our machine screws are hex-headed; you might need a screwdriver instead if you’re obtaining your own hardware)
  • An 8mm socket, spanner or pliers

You’ll also need a clean, well-lit workspace with a heat-resistant surface to work on.

Build Instructions

Putting our Power module together is very straightforward; the parts count is low and the parts are easy to identify.

Components go on both sides of the PCB – these instructions will highlight this as you go along but as a general rule – parts go on the side of the PCB that has a marking for them.

Solder parts into the marked positions; where a part has to go a specific way round there will be markings on the PCB to guide you, and a clear note in the instructions.

Typically we add parts to the board in height order, starting with the shortest parts (this makes the PCB easier to manage and handle during the build). We’ll only deviate from this approach occasionally where it’s sensible to do so.

R1, R2 and R3 – resistors

_MG_7646_thumbWe’ll start on the “front” of the PCB. This is the side that doesn’t have the word “POWER” printed on it. Locate the positions for R1, R2 and R3. Refer to the Bill of Materials to see which values go where (if you’ve bought one of our kits, you’ll have found that all of the parts are clearly labelled). Make sure that you put the correct values in the right places – check them against an identification chart or with a meter if you’re unsure. Solder all of the resistors into place once you’re certain you know what goes where. It doesn’t matter which way round they go as long as they’re in the right location. You can tidy the wires now with a pair of cutters or do them later (I tend to do mine as I go along as it makes the PCB easier to photograph).

J3 – 4-pin header

_MG_7647_thumbThis pin header goes on the other side of the PCB from the resistors. You’ll find the marking for it on the same side of the PCB as the word “POWER”. Locate the pin header in the holes, flip the PCB over and solder into place.

You might find it useful to just solder one pin, then check that the header is straight, making any adjustments before soldering the remaining 3 pins.

JK1 – Power inlet

_MG_7650_thumbJK1 will only fit one way – note how the pin arrangement is “keyed”. Don’t be tempted to solder it into place immediately, though – we have to ensure it aligns with the top panel correctly before we solder it. The first thing we need to do, therefore, is put the mounting standoff posts in place so that our top panel has something to attach to.

Attach a post into each of the two M3 holes and secure it in place with a nyloc-style nut. Make sure they’re nice and snug but don’t overtighten – you don’t want to crush the PCB.

Now put JK1 in place but, again, don’t solder it yet. Instead fit your top panel in place, using M3 machine screws to locate it onto the tops of the posts. Don’t tighten the screws up beyond finger-tight as you’ll need to remove the panel again in a minute.

_MG_7652_thumbEnsure that the power inlet hole in the panel and the hole in the component align nicely; jiggle JK1 around a bit if you need to. Plugging in a 2.5mm plug can be useful here, too – but make sure it’s not connected to mains!

When you’re sure you’ve got it aligned, flip the whole thing over and solder JK1 in place. The holes for the pins are pretty big so be generous with the solder, remembering to heat the pin, the pad and the solder all at the same time to ensure a good connection.

When that’s done and cooled, remove the top panel again and set it aside.

J1 and J2 – wired AC out


The connection between your Power module and your PSU inside your case is a simple pair of wires.

Take the wires provided and strip a centimetre or so of insulation form each end. Twist the strands together and then tin the exposed copper with some solder and your soldering iron.

Locate points J1 and J2 on the PCB. Feed a wire (it doesn’t matter which colour) through the strain-relief holes adjacent to it and insert the tinned end of the wire into the copper-surrounded hole right next to the “J1” label. Solder the wire in place and trim any excess.

Now repeat this process for J2 and the other wire.

Finally, twist the wire strands together along their full length.

SW1 – toggle switch

We’re now going to fit the toggle switch and properly fix the front panel into place.

Locate the position for the switch, on the same side of the PCB as your standoff posts. Insert the switch into the holes – it doesn’t matter which way round it goes. On early versions of this PCB, these holes are quite tight so you’ll need to gently rock the part from side to side as you insert it in order to “ease” the copper around the holes (this will be rectified in the next batch of this PCB).


When you’ve got the switch in place, insert the three LEDs into place. For each of these the long lead goes through the hole marked “+”. Pay careful attention to the PCB markings as LED1 is oriented differently to the other two. We’re not going to solder these yet, so for now allow the LEDs to sit against the PCB, then widen their leads slightly so that they stay out of the way while we work on the switch.

Remove the outer nut and the washer from the switch. Flip the washer over so that the key tab doesn’t stick out and put it back on the switch.

Now, place the front panel into position again and secure it with the two M3 machine screws. This time, you can tighten these up as we’ll not need to remove the panel again.


Adjust the nut that’s on the switch shaft to raise the washers right up against the panel. Ensure that the panel sits parallel to the PCB along its whole length.

Now flip the assembly over and solder the switch into place. Again, these are quite large holes so be as generous as you need to with the solder.

LED1, 2 and 3 – indicator LEDS

_MG_7667_thumbIf you’ve bought our kit or our recommended parts you’ll have some very smart flat-topped LEDs. Obviously, these look their best when they’re mounted absolutely flush with the panel and with each other. If you’re using these LEDs, we strongly advise putting a piece of masking tape on the front of the panel to hold your LEDs in place while you solder them. Position the tape first, then locate the LEDs into place. Flip the assembly over, solder the LEDs into place and trim the leads.

_MG_7670_thumbWith that done, we’re finished with soldering, so you can switch your iron off now.

Carefully remove the tape from your panel – your LEDs should be nicely flush to the panel.


Put the remaining nut over the switch and tighten it up to finally secure the panel into place. You’re done and your module is ready to use!

Connecting to Dualist

Although it can be used with any power supply module with a little modification, it’s primarily designed to be used with our Dualist power supply. Hooking up the module is very simple. Note that you may want to fit the module into your rack before doing this.

AC connection

_MG_7679_thumbThe twisted pair of wires from the Power module connect to the screw terminals J3 on the Dualist board. Because the supply is AC, it doesn’t matter which wire connects to which terminal.

To connect, loosen the screws, insert the tinned ends of the supply wires into the terminals, then tighten the screws again.

LED indicators

_MG_7676_thumbThe LED indicators in the Power module draw power from the output rails of your Dualist. To connect this up, use the provided four-way wired sockets to connect J3 on the Power module to J2 on the Dualist board.

Both of these headers have the same pin assignments, so connect pin 1 to pin1, pin 2 to pin 2, etc. Pin 1 is denoted by a square printed outline on the PCB (the other pin outlines are octagonal).

Important note: The 5V indicator LED will only operate if a 5V rail supply has been fed back to the Dualist module via J1 on the Dualist board. The Dualist module itself only powers the +12 and -12V rails. Our ThirdRail add-on provides a suitable 5V rail.

Powering up

_MG_7682_thumbThe Power module requires a 12V AC-AC supply and uses the same size 2.5mm barrel socket as is used on the Dualist board (we chose the 2.5mm component as we found that in this application they seem to “latch” more securely than equivalent 2.1mm connectors). We’ve found some suitable power supplies here (1A) and here (2A, which we recommend), but both are supplied with 2.1mm connectors; if you bought a Dualist kit, you’ll have received a 2.5mm replacement plug as part of the kit, however if you need to obtain one of these they’re available from one of our favourite suppliers.

Important note: Dualist (and hence this module) requires a 12V AC power supply; you can’t use a DC power supply with this module or with the Dualist PSU. You must not try to power this module or the Dualist PSU directly from mains voltage!

Bill of Materials

In addition to your PCB and panel, you’ll need parts. The full list of parts for the project is given below, with Mouser and BitsBox part numbers to aid you in identifying compatible parts. Although we’ve used all Mouser and BitsBox parts in the example build above, you may be able to obtain cheaper compatible parts by shopping around.

Reference Value Description Qty Supplier &  Part Notes
J3 4-pin male IDC header 1 Mouser – 571-6404524
JK1 2.5mm Switched PCB mount DC socket, vertical 1 Mouser – 490-PJ-044B Recommended for good latching
LED1, LED2, LED3 3mm red LED, flat-top 3 Mouser – 604-WP424SRDT Recommended
R1, R2 330R Resistor, metal film, 0.25W, 1% 2 Mouser – 603-MFR-25FRF52-330R
R3 220R Resistor, metal film, 0.25W, 1% 1 Mouser – 603-MFR-25FRF52-220R
SW1 ON-ON DPST miniature toggle switch 1 Bitsbox.co.uk – SW005
M3, 14mm Standoffs 2 Mouser – 855-R30-3001402
M3 x 6mm Machine screws 2 Use eBay or local hardware store
M3 “Nyloc” nuts 2 Use eBay or local hardware store
4-way F-F 20cm wired sockets 1  Bitsbox.co.uk – CN395
Red Stranded Wire 16/0.2mm, 25cm 1 Bitsbox.co.uk – W1602RD
White Stranded Wire 16/0.2mm, 25cm 1 Bitsbox.co.uk – W1602WH