Building Scarp


You’ll need the usual.

  • Soldering iron,
  • solder (I use .5mm solder),
  • clippers,
  • kneedle nose pliers (or similar)
  • I need a magnifying glass
  • good light.
  • small screw drivers
  • multimeter? I like em.


All parts are labeled on the bottom pcb and parts in the kit are labeled.

Start with the resistors and the diode. I usually mount 2 at a time, and alternate with pins from one to the other to keep from heating any part too much.

Leave the last 1Kohm resistor underneath clkaudio for later. It’s a bit too close to the pot so we’ll get to it later.


Trim directly to let your iron heat up and keep from having pins get in the way.

keep it trim!

Now onto the buttons. Sometimes they need a wiggle and are wont to bend. You may need to hold them in place if they don’t ‘snap’ in.


Now the audio jacks. They are a bit difficult to squeeze in as the pcb does not have slots but holes (limitation of using Fritzing). Be careful not to push down and bend a leg under the housing. You can wiggle squeeze them down. I usually flip the board back and forth checking from sides and bottom to make sure I haven’t bend the pins.

audio jacks pins ...

I usually do soldering in two rounds. First a bit of solder to hold, then trim the legs, then solder fill.

audio jacks

Move on to the leds. The long, anode+, end goes in the square pads. I usually mount two, with one space between and solder alternate legs on alternate leds.

legs akimbo!

all lit up!

We can move onto transistor and the capacitors. The transistor, I usually mount and bend. You don’t need to, but since the hole spacing is a bit ’too large’ for the 3904, wich I do to keep the option open for a larger transistor (why?) it’s just easier to leave some space. And it means it’s easy to fix should the transistor fry (unlikely in this lifetime).

resistors & caps

Now, place the headers, but don’t solder immediately. I usually place all three since they create a more stable support together and it’s easier to get them sitting flat. You can build a support jig by, for instance, putting pins in breadboard to hold the headers straight. I just usually apply a bit of downward pressure, look that the pins are ‘centered’ solder one corner on each row and check if it’s fine. If the headers sit right, I solder a pin on the opposite side, and check again.

pico & display headers

Now we come to the last 1Kohm resistor we left at first. We’re going to do a vertical here, as depicted. I usually place a 10K pot at this time to make sure the spacing is ok.

one 1K left standing!

Now on to the pots and encoder. Start with the one next to the resistor we just soldered. Start by hold the pot ‘flush’ so that it sits on it’s support and solder one pin. Check if it’s sitting flat and then move on to encoder and the final pots.

pots one pin ....

Start by holding the pots so they ‘sit’ straight and solder a single pin. Turn over and to the side to see if the pot is sitting properly then finish the rest of the pins or reheat and reseat the pot. For the fat supports, I also do this in two round, a little solder to hold and then trim and fill. But, since the rampart has higher rubber feet, you can just fill solder and trim.

(NOTE, I’ve forgotten the switch!)

With the pot supports I tend to solder a bit clip short and then add more solder. We don’t want the full legs poking out since we’re adding a base plate….

pots supports

Get the base plate and the battery holder. Make sure you use the same orientation (the plus side is where the diode and switch are located) for the base plate and solder the battery holder to the base plate.

battery holder

Prep the the red and black wires for connecting the two boards.

battery wire!

And don’t forget anything you want on top before we solder the wires ;) I had forgotten the switch. But you might want to add extra headers for an audio dac. There are variations on this (lower headers, for instance) so, think about it first. I don’t supply those headers since I’m uncertain myself :)

ah, who needs an off switch!

ah, maybe the headers for audio?

In the picture, I swapped the colors! Usually red is positive, but I accidently swapped. Don’t :) I insert, bend the wire flush with the board, then solder from the top.

wires from botton through to top...

And then solder the wires to the legs of the batter holder on the bottom plate

We have attached the plate!

If you haven’t already, you need to add the headers to the pico now. I use a bit of breadboard or permaboard to keep things aligned.

perma pico

We’re nearly done! At this point, if the chip isn’t already flashed (I ship flashed), I flash and do a functional test. And then I bolt everything down, add the pot knobs and make some funny music!

nuts & bolts, finally!


You rock!

now where did I put those knob thingies .....