Helium self-sourcing build guide#

Welcome to the guide for self-sourcing and building Helium. This guide is for folks who want to build a Helium on their own from bare printed circuit boards and components.


This process is not for the faint of heart! You'll need to find, purchase, assemble, and test everything yourself. If you just want to have fun putting together a kit, consider our Helium DIY kit which includes everything you need with a fully tested PCB that has all of the surface mount assembly done, leaving just the through-hole bits to you.

Self-source DIY kit Fully assembled
Surface mount components soldered
Fully tested
Through hole components soldered
Difficulty Expert Easy None!

Please read all instructions thoroughly before starting. If you have questions or run into trouble please reach out to us on discord or drop us an email at support@winterbloom.com, though note that we have limited resources for supporting self-sourced builds.

With all that said, we hope you have a great time putting this module together and a wonderful time using it. Good luck!

Skills required#

Building a Helium from scratch requires patience, care, and skill. Helium can be a great a project for learning these skills, but we do recommend being careful with some of the more expensive components. Though not strictly required, we recommend that you have:

Tools required#

Before you begin, make sure that you've got:

If you want to be extraordinarily well prepared:


Though it's not required, you may find it useful to refer to Helium's schematic during your build. You can find it by downloading either:

PCB & faceplate#

You'll need to source a printed circuit board (PCB) and faceplate for Helium. You have two options:

  1. You can buy them directly from Winterbloom. These are extremely high quality boards built to our specifications. This is an especially good option if you live in the United States.
  2. You can have them made for you by a PCB fab such as OSHPark or PCBWay. You'll generally receive multiple boards so this can be advantageous if you're planning on building several Heliums.

If you choose to have a fab make your boards, you'll need to provide Gerber files for both the board and the faceplate. We highly recommend preparing these from the KiCAD source files based on your fab's instructions. These can be found on GitHub:

However, you can also download pre-made Gerbers which should work for most fabs:

Faceplate differences

The faceplate published on GitHub differs slightly from the faceplates sold by Winterbloom in that our logo has been removed.

We recommend giving your fab the following specifications:

Cheap fabs

There are many options for PCB fabs these days, but keep in mind that picking the absolute cheapest option does come at the cost of quality. Use with caution! If in doubt, just grab a PCB and faceplate from us.

If you're making multiple Heliums, we'd recommend picking up a solder paste stencil since it'll make assembly go a bit faster. Usually your PCB fab can provide them along with your boards.

Bill of materials#

Below is the bill of materials for Helium's electronic components, including part numbers and purchase links.

Reference Value & Rating Footprint Qty Part no Digi-Key Mouser LCSC Notes
C1, C2 10µF
0805 2 Murata GRM21BR61E106KA73K 490-16824-1-ND 81-GRM21BR61E106KA3K C3909351 5
C3-C10 100nF
0603 8 Samsung CL10B104KB8NNNC 1276-1000-2-ND 187-CL10B104KB8NNNC C1591 5
C11 18pF
0603 1 Yageo CC0603JPNPO9BN120 13-CC0603JPNPO9BN120CT-ND 603-CC603JPNPO9BN120 C1853092 5
R1-R3, R5-R7, R12-R14, R17 51Ω 100mW/±1%/Thin 0603 10 Yageo RT0603FRE0751RL 13-RT0603FRE0751RLCT-ND 603-RT0603FRE0751RL C849799 5
R4, R8, R15, R18-R20 100kΩ
0603 6 Susumu RG1608N-104-W-T1 RG16N100KWCT-ND 754-RG1608N-104-W-T1 C1722256 1
R9-R11, R16 1.5kΩ
0603 4 Yageo RC0603JR-071K5L 311-1.5KGRCT-ND 603-RC0603JR-071K5L C114680 5
FB1, FB2 1kΩ @ 100MHz
0603 2 Murata BLM18AG102SN1D 490-1015-1-ND 81-BLM11A102S C85824 6
D1, D2 Schottky
SOD-123 2 Nexperia PMEG2005EGWX 1727-7329-1-ND 841-PMEG2005EGWX C133636 4
D3, D5, D7, D9 Positive LED
0805 4 Kingbright APT2012VBC/D 754-1794-1-ND 604-APT2012VBC/D C5879386 2
D4, D6, D8, D10 Positive LED
0805 4 Kingbright APT2012VBC/D 754-1133-1-ND 604-APT2012SURCK C5875730 2
U1, U2, U4, U6 OPA4991 TSSOP-14 4 TI OPA4991IPWR 296-OPA4991IPWRCT-ND 595-OPA4991IPWR C2873620 2
J1 2x5 2.54mm
IDC Header
- 1 On-shore 302-S101 ED1543-ND 710-61201021621 C429962
J2-J5, J7-J10, J12-J15, J17-J20 Audio jack - 16 WQP-WQP518MA Available from Winterbloom or Thonk


  1. If you are trying to reduce costs, you can swap the expensive 100kΩ 0.05% resistors for much more affordable 0.1% or 0.5% resistors at the cost of reduced accuracy in the voltage adder circuit.
  2. You can also swap the expensive OPA4991 op-amp with a more affordable alternative, such as OPA4171, OPA1679, or OPA4197. We don't recommend going with TL074 due to it exhibiting phase reversal.
  3. The LEDs are known to work well with the faceplate's FR4 "diffusers" when using at most 10 mA. If you use different LEDs, try to get them around 200 mcd @ 20 mA. You can adjust their brightness & current consumption by changing the 1.5kΩ resistors.
  4. The two Schottky Barrier Diodes can generally be swapped for any SOD-123 or SOD-123F Schottky with a reverse voltage VR20 V, a forward current of IF500 mA, and a forward voltage VF400 mV. Most other PMEGxxxxEG parts work well.
  5. Passive components such as resistors and capacitors often fluctuate in stock. They can be substituted with equivalent parts as specified by their rating. For capacitors, the rating is Voltage/Tolerance/Dielectric, for example 24V/±10%/C0G. For resistors, the rating is Power/Tolerance/Composition, for example 100mW/±1%/Thin. If part of the rating is left off, then it doesn't matter.
  6. The ferrite beads can be swapped with similar 0603 ferrites with a DC current rating of ≥ 300 mA. The ones we use have an impedance of 1 kΩ @ 100 MHz.

Component orientation#

Before you start placing components, take a chance to note the correct orientation for components such as diodes, LEDs, large capacitors, and ICs.

For LEDs and diodes, the PCB and the components have corresponding cathode marks on one side. LEDs typically have a green marks on the top and a green triangle on the bottom, whereas diodes have a lighter stripe drawn across one side.

A photo showing the proper alignment of LEDs
A photo showing the proper alignment of diodes

Use additional caution soldering LEDs, as overheating them or melting their lens can destroy them.

Integrated circuits (ICs) also must be installed in the correct orentation. Most larger ICs have a circle in one corner that designates pin 1. This should be matched with corresponding black circle or star on the board. The assembly diagrams below also highlight pin 1 in green.

IC alignment

If in doubt, double check the chip's datasheet.


Helium has components on both sides of its board. We recommend starting with the back and then doing the front, since the majority of components are on the back. This is especially true if you're using a stencil and solder paste instead of an iron, as you'll want to be able to reflow the boards before placing the LEDs on the front side. We recommend that you start with the largest components first and work your way down to the small passives.

The interactive tables and images below show where to place each component.

Inspection & cleaning#

Before moving on, take a moment to carefully inspect the PCB. Keep an eye out for:

This is also a good chance to clean your board. We highly suggest following the instructions for your solder and flux. If in doubt, isopropyl alcohol and a cotton swab can be used to remove flux residue but look out for no-clean flux as it can turn sticky if not completely removed when exposed to alcohol.

Next steps#

Congratulations, you have completed the hardest part! All that remains is assembling the through-hole components and putting on the faceplate. You can follow the kit build guide to finish up.

Support us#

We made everything open source and put together this guide because we want you to be able to build, repair, and truly own your Helium. We don't expect anything in return, but if you'd like to show us some support feel free to: