# Prototyping DIY Expression Pedal interface for Kosmo

**URL:** https://lookmumnocomputer.discourse.group/t/prototyping-diy-expression-pedal-interface-for-kosmo/649
**Category:** KOSMO MODULES
**Created:** [April 17, 2020, 1:18am UTC](https://lookmumnocomputer.discourse.group/t/prototyping-diy-expression-pedal-interface-for-kosmo/649 "2020-04-17T01:18:51Z")
**Posts on this page:** 1
**Showing post:** 34

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### Author: ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)
#### Post date: [June 7, 2020, 11:03am UTC](https://lookmumnocomputer.discourse.group/t/prototyping-diy-expression-pedal-interface-for-kosmo/649/34 "2020-06-07T11:03:03Z")

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> [@DIY Power Supply Thread - Questions and Help](https://lookmumnocomputer.discourse.group/t/diy-power-supply-thread-questions-and-help/117/39):
>
> The TL072 rails are backwards, right? (unless you’re using red for −12 V in case your color coding is backwards, and your caps too 😀).

Yes, red must be +12V since that’s what’s connected to the tip switches. But then the power connections on the TL072s are reversed.

(I’m surprised you didn’t use a TL074, but I suppose you had reasons.)

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