# Help modding Pendulum Harmonic Tremolo schematic, switches for in phase and low pass unaffected?



## alonkka (Apr 15, 2022)

I want to mod Pendulum Harmonic Tremolo (schematic) in two ways and could use some help since I'm not a skilled schematic reader or circuit designer. These are both features I like on my Zepplin Design Labs Quaverato and want to try adding to this pedal.

First, switch between out of phase (harmonic) and in phase tremolo. I believe I would do this by reversing the phase on either the high pass or low pass filter (or bypassing whatever is reversing it). 

Second, a switch to pass the low pass side through with no modulation so that only the high pass side is being modulated. (i.e. low notes are not-modulated, high notes are modulated)

Could you provide any details about what I should be looking for on the schematic or doing to achieve this? Thank you very much. I'll post this on reddit as well and update either place if I get a response.


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## Bricksnbeatles (Apr 15, 2022)

Take a look at how it’s done here— this is the schematic for the Drolo Twin Peaks tremolo, which has both of the features you’re asking about. I didn’t get to look at the two to see the similarities and differences, but it should give you a decent idea of how to implement it



			https://www.delykpcb.com/product/cherry-pie-tremolo-pcb/?attachment_id=1059&download_file=9k6uqgu17ljgo


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## Funnel (Apr 16, 2022)

You can also take a look at the cardinal harmonic tremolo schematic. It has a similar feature set. The harmonic/bright/regular trem setting is done with a toggle switch opposed to the twin peaks rotary switch. Both are good tremolos and can give you ideas on how to implement what you are wanting. https://cdn.shopify.com/s/files/1/0022/3952/9069/files/Cardinal-Trem-V2.pdf?16138734983046189115


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