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Thanks everyone,</div>
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The portmento pedal is normally closed, push to open the terminals, and yes in my previous message I mentioned it is a mk I odyssey.</div>
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The pedal’s ground is not connected to the jack, sould I ground the velocity output jack to the ody? I assume so.</div>
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An optoisolator is also an option.</div>
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Good to know a bjt can do it theoretically.</div>
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Ed</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Synth-diy <synth-diy-bounces@synth-diy.org> on behalf of Michael E Caloroso via Synth-diy <synth-diy@synth-diy.org><br>
<b>Sent:</b> Friday, November 28, 2025 10:39:06 AM<br>
<b>To:</b> Oren Leavitt <oleavitt@proton.me><br>
<b>Cc:</b> synth-diy@synth-diy.org <synth-diy@synth-diy.org><br>
<b>Subject:</b> Re: [sdiy] Fet to short pedal input?</font>
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<div dir="ltr">The dark resistance of any LDR is always going to be in parallel with the 1M pot, which will reduce the max portamento rate.
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<div>You really need a control element with infinite resistance (open circuit). That element needs to have open circuit and short circuit states and it's hard to beat a relay controlled by a Darlington BJT.</div>
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<div>Routing MIDI note velocity to Portamento enable is a neat expression tool - it's a trick I use on choir patches on my Andromeda. Pitch glides only at high velocity, and you don't need an extra hand to toggle it.</div>
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<div>MC</div>
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<div dir="ltr" class="x_gmail_attr">On Fri, Nov 28, 2025 at 9:26 AM Oren Leavitt via Synth-diy <<a href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</a>> wrote:<br>
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Looks to me like a simple LDR (LED/photocell) may do the trick here. <br>
Given the LDR has sufficiently high "dark" resistance.<br>
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- Oren<br>
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On 11/28/25 5:47 AM, Tom Wiltshire wrote:<br>
> I've checked the Arp Odyssey schematics (since it has one of these <br>
> inputs). The relevant part is attached below.<br>
> <br>
> The Portamento input jack is a TRS jack connected across the ends of the <br>
> 1M audio-taper portamento pot. So shorting the Tip and Ring connections <br>
> disables the portamento. It's not a simple short-to-ground action as I <br>
> had thought it might be, but any bidirectional switch should work in <br>
> this position.<br>
> <br>
> <br>
> <br>
>> On 27 Nov 2025, at 20:34, el macaco via Synth-diy <synth-diy@synth- <br>
>> <a href="http://diy.org" rel="noreferrer" target="_blank">diy.org</a> <mailto:<a href="mailto:synth-diy@synth-diy.org" target="_blank">synth-diy@synth-diy.org</a>>> wrote:<br>
>><br>
>> Hi all,<br>
>><br>
>> The portamento pedal input on arps has me thinking of using my midi to <br>
>> cv converter's velocity output (+5V) to activate a fet with the two <br>
>> pedal contacts on the source and drain.<br>
>><br>
>> Can it be this simple? The only power coming from the velocity 5v?<br>
>><br>
>> Thanks,<br>
>><br>
>> Ed<br>
>><br>
>> Get Outlook for iOS <<a href="https://aka.ms/o0ukef" rel="noreferrer" target="_blank">https://aka.ms/o0ukef</a>><br>
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