<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">+1 agree with Benjamin. Decoding key contacts and producing midi notes is very simple.<br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 22 May 2026, at 02:37, Benjamin Tremblay via Synth-diy <<a href="mailto:synth-diy@synth-diy.org" class="">synth-diy@synth-diy.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="content-type" content="text/html; charset=utf-8" class=""><div dir="auto" class="">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 class="">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 class="">I’m lazy. Once I solder it up I just adjust a map in software until key numbers make sense .<br id="lineBreakAtBeginningOfSignature" class=""><div dir="ltr" class="">Benjamin Tremblay</div><div dir="ltr" class=""><br class=""><blockquote type="cite" class="">On May 21, 2026, at 9:14 PM, Didier Leplae via Synth-diy <<a href="mailto:synth-diy@synth-diy.org" class="">synth-diy@synth-diy.org</a>> wrote:<br class=""><br class=""></blockquote></div><blockquote type="cite" class=""><div dir="ltr" class=""><meta http-equiv="content-type" content="text/html; charset=utf-8" class="">Does anyone have ideas about adding MIDI capability to a cheap keyboard that doesn’t have midi out? <div dir="ltr" class=""></div><div dir="ltr" class=""></div><div class=""><br class=""></div><div class="">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. 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