<html class="apple-mail-supports-explicit-dark-mode"><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">I have had some luck scanning vintage toy keyboards. Cheapest way I know is to use the Arduino “mega pro mini” which is a miniature clone of the Arduino Mega . I see them for $10-20 online. It has lots of pins and multiple serial ports, and running at a full 5v seems to matter when scanning rubber buttons. Almost always these are an X *. Y matrix and the hard part is sorting out the pins/wires into which dimension each one belongs to. <div>Once you have a theory about how the pins work, write a tiny program to scan the pins where you set pins on “X” dimension high one at a time, and then read each “Y” pin to see if it’s high one at a time. If the circuit already has diodes, great, otherwise you may have to add diodes to support chords. </div><div>I’m lazy. Once I solder it up I just adjust a map in software until key numbers make sense .<br id="lineBreakAtBeginningOfSignature"><div dir="ltr">Benjamin Tremblay</div><div dir="ltr"><br><blockquote type="cite">On May 21, 2026, at 9:14 PM, Didier Leplae via Synth-diy <synth-diy@synth-diy.org> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr"><meta http-equiv="content-type" content="text/html; charset=utf-8">Does anyone have ideas about adding MIDI capability to a cheap keyboard that doesn’t have midi out? <div dir="ltr"></div><div dir="ltr"></div><div><br></div><div>A friend of mine is interested in using a piano mat, made for kids, in performances, but these kinds of keyboards are very limited in their sounds. So, I wondered how feasible it would be to add a midi out.</div><div><br></div><div><div style="display: block;" class=""><div style="-webkit-user-select: all; -webkit-user-drag: element; display: inline-block;" class="apple-rich-link" draggable="true" role="link" 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