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My Designs Phaser

Airmed – My Take on a Simple Phaser

Here’s my take on a simple two stage phaser similar to Phase 45. I called this pedal – Airmed – The Healer.

For previous posts have a look here. As usual you can skip to the video and come back later for diagrams.

The Healer?

Airmed was an Irish goddess associated with healing. When king Nuada lost his arm, she built him a replacement arm of flesh so he could rule his people again*. Well, this pedal does something similar – heals your sound so it sounds like you have three arms ?. Or at very least makes you want to play longer and thus improve your skills ?.

* this may or may not have been based on a true story

This is not a very original pedal, but I liked the sound and wanted to try doing something little extra with it. It’s very subtle, but it gives a sort of a motion to the sound. Whenever I play through it, it keeps making me want to play more, and every time I change the rate of the phaser I come up with different melody. It’s by no means lush or crazy swooping or whatever you might get from more complex phasers. But lots of times, we need just a little bit of good stuff ?

Schematic

The schematic is just a combination of the previous few posts. I only did some changes to the LFO to give myself more control over it. Other than that, I had to split the design into 3 different PCBs. I reused my stomp switch board from Cliodhna – The Queen. But I split the schematic into LFO part and the “effect” part since it could not fit into 1590B enclosure otherwise.

If you watch the video, you’ll get a bit more detail on how I designed this. One added benefit of two boards is that I can reuse LFO for other work if I want to. Here’s the schematic:

Schematic showing LFO part of The Healer phaser effect
Airmed – The Healer – LFO (click for full image)
Schematic of the effect part of The Healer phaser
Airmed – The Healer – Effect (click for full image)

Mods

Most of the differences are from playing with LFO post. I added some LED indicator of rate. And finally, I used TL074 in several places, and completely removed transistors from the audio path. Not for sound, just for practicality because I had unused op-amp.

On top of this, I kept biasing of LFO separate. This way LFO board is independent and could be possibly reused for something else (if it ever comes to that ?.

With the above in mind – I have 3 knobs – standard Rate knob, but also – “Swing” and “Bias”. Swing just controls the amplitude of the saw signal of the LFO. Using it disturbs the bias slightly, so Bias knob is there to fine tune it. There’s standard trim pot for bias configuration.

To set the trim pot – set maximum Bias, set Swing between 80 and 90% and set the trim pot. That should give you best versatility.

PCB

I got PCBs as usual from PCBWay. I’m not sure if I can submit all 3 boards at the same time, I ordered them one by one. I used handy PCBWay plugin for KiCad to order the boards easily.

The boards look exactly as you would expect from the 3D view.

Without further ado. The video – enjoy.

Video

Watch and be healed

Conclusion

It was a bit tricky to demo this. I messed up the order for my pots, so couldn’t complete the pedal. As soon as I source the right pots I’ll be rectifying this and posting another video. Hopefully that moving sound comes across despite the subtleness. Mental note for next time – use some overdrive too ?

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