Meet Helios! Bi-Polar power supply REV B boards coming soon! Edit: Now available! – (Updated: 4th Feb 2021)

After the success and popularity of the first Bi-Polar power supply REV A boards, I decided to tidy it up and improve on it a little. But first, lets take a look at the new REV B board.

Helios – Bi-Polar Power Supply (REV B).

I decided it was time to start giving the boards names so it avoids confusion in the future. So whenever somebody requests a power supply PCB, I will know which one they are referring to assuming they mention it by name.

Now lets get to the changes. You may or may not notice several improvements over the previous REV A boards.

– Improved the trace layout and eliminated all vias.
– Added an R10 resistor footprint as an optional alternative to using the U3 CL220 LED Driver.
– Moved C8 and C9 output caps further away from the CL220 to reduce possible heat transfer.
– Changed contact type on copper fill ground plane from thermal relief to solid on bottom of PCB.
– Minor improvements to silkscreen labeling and added High Voltage safety notice and board name.
– Offset the bottom two mount holes for more secure mounting inside Hammond 1455T2201 enclosure.
– REV B boards will be Electro Nickel / Immersion Gold (ENIG) instead of Lead (HASL).

The boards have arrived from the fab house and are now available. I have made some changes to the original article to reference the new REV B boards and point out some differences.

The BOM list remains unchanged but you may need an extra resistor for R10 if you choose not to populate the U3 CL220.

The new REV B board with immersion gold contacts.
Another view of the new REV B board. Note the addition of the R10 resistor.

If you would like to get in touch then please drop an email to and I will get back to you as soon as possible.

Thank you everyone for you’re support and stay safe!

7 thoughts on “Meet Helios! Bi-Polar power supply REV B boards coming soon! Edit: Now available! – (Updated: 4th Feb 2021)”

  1. Very nice boards! Will use for my Wayne’s BA2018 linestage. Is it possible to use a 5K Bourns trim pot at R10 when using the external LED hook-up?

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