Last weekend Tim described the brain chemical acetylcholine and how it related to hacking learning and memory. There were a lot more technical terms in that show than most previous shows.
Long wooden keys were revised to be closer to actual piano key dimensions. The weighting from such slender pieces was difficult to make them return to a resting position without springs.
Working with the thin wood was expensive and didn't provide enough benefit. The purpose of the instrument was never to appeal to professional pianists so less expensive wood was chosen. Wider keys seemed acceptable since they still looked like piano keys even if they were a chunkier version.
A huge revision to the project happened when the decision was made to use arcade buttons instead of keys. This change was made after talking to someone who works closely with kids in music therapy. Since the shape of the switches wasn't important rugged arcade buttons seemed like a good choice. They are readily available, easily replaceable by untrained people, inexpensive and meant to take a lot of abuse.
A CAD drawing was made with the layout for a single octave then printed four times. Four octaves worth of arcade buttons came to nearly four feet (1.3m). White and black buttons could be used to make it clear that a piano sound would come out of the device when the buttons were pressed although this was merely a matter of style on my part more than functionality.
The holes were drilled to arcade button size in a piece of 1x6 lumber and a piece of plastic long enough to cover all the buttons. Plastic was purchased locally from a surplus store. Presumably, the plastic was HDPE (High-Density PolyEthylene). Covering the wood with plastic was to prevent slivers and give it a clean look to match the plastic buttons.
Programming for the Raspberry Pi Zeros was done awhile ago and tested with simple tactile switches. It would have been possible to solder each arcade button to the Pi itself but an adapter board seemed like a cleaner option. This way a replacement Pi could be installed by anyone capable of soldering a 2x20 header strip to the board and probably by just using a computer from the full-fledged line of Raspberry Pis.
After the adapter board was made the testing was very troublesome. The notes would not stop playing. Nothing was done to ground the wires so they were all "floating" and highly prone to interference. A short video was taken to demonstrate the effects of floating wires.
A revision to the adapter board would be necessary. The first testing was done with short wires so floating wires were less of an issue but long wires each acted as an antenna.
A diagram was sketched which linked each of the Raspberry Pi Zero's pins to the correct arcade button. The switches were still drawn as piano keys for clarity. Pins for the octave selector wheel were also drawn.
Pull-down resistors were added to the first board wherever they could fit. It was not a clean solution but the solder joints were thick enough to keep things in place. The next three copies of the board, one for each octave, would have the resistors taken into account before constructing.
When the resistors were installed the board was mounted in the middle of one octave in the Tough PiAno. All the wires were trimmed and terminals were crimped to each end. The wire colors were arbitrary but recorded on the schematic sheet so they could be duplicated in the rest of the octaves. Switches were taken from stock so they don't match.
Testing was done on the adapter board by connecting a Raspberry Pi Zero with the Tough PiAno software running. Some of the switches performed unreliably so hopefully the switches that were ordered are all functional when they arrive.
A wooden base was built on three sides. The base will give everything room on the inside. It will be held to a wooden shelf underneath by using bolts from the underside which will couple into threaded wood inserts.
Brian - Left. Tim - Right.
Long wooden keys were revised to be closer to actual piano key dimensions. The weighting from such slender pieces was difficult to make them return to a resting position without springs.
Slender wood keys
Working with the thin wood was expensive and didn't provide enough benefit. The purpose of the instrument was never to appeal to professional pianists so less expensive wood was chosen. Wider keys seemed acceptable since they still looked like piano keys even if they were a chunkier version.
Using gravity return on some of the piano keys
A huge revision to the project happened when the decision was made to use arcade buttons instead of keys. This change was made after talking to someone who works closely with kids in music therapy. Since the shape of the switches wasn't important rugged arcade buttons seemed like a good choice. They are readily available, easily replaceable by untrained people, inexpensive and meant to take a lot of abuse.
A CAD drawing was made with the layout for a single octave then printed four times. Four octaves worth of arcade buttons came to nearly four feet (1.3m). White and black buttons could be used to make it clear that a piano sound would come out of the device when the buttons were pressed although this was merely a matter of style on my part more than functionality.
Marking the center holes from the CAD print
The holes were drilled to arcade button size in a piece of 1x6 lumber and a piece of plastic long enough to cover all the buttons. Plastic was purchased locally from a surplus store. Presumably, the plastic was HDPE (High-Density PolyEthylene). Covering the wood with plastic was to prevent slivers and give it a clean look to match the plastic buttons.
Drilled wood and plastic
Programming for the Raspberry Pi Zeros was done awhile ago and tested with simple tactile switches. It would have been possible to solder each arcade button to the Pi itself but an adapter board seemed like a cleaner option. This way a replacement Pi could be installed by anyone capable of soldering a 2x20 header strip to the board and probably by just using a computer from the full-fledged line of Raspberry Pis.
Raspberry Pi Zero installed on an adapter board made for the Tough PiAno
After the adapter board was made the testing was very troublesome. The notes would not stop playing. Nothing was done to ground the wires so they were all "floating" and highly prone to interference. A short video was taken to demonstrate the effects of floating wires.
Video demonstration of floating signal wires
A revision to the adapter board would be necessary. The first testing was done with short wires so floating wires were less of an issue but long wires each acted as an antenna.
A diagram was sketched which linked each of the Raspberry Pi Zero's pins to the correct arcade button. The switches were still drawn as piano keys for clarity. Pins for the octave selector wheel were also drawn.
Old testing board and key schematic
Pull-down resistors were added to the first board wherever they could fit. It was not a clean solution but the solder joints were thick enough to keep things in place. The next three copies of the board, one for each octave, would have the resistors taken into account before constructing.
Resistor haphazardly connected to adapter board
When the resistors were installed the board was mounted in the middle of one octave in the Tough PiAno. All the wires were trimmed and terminals were crimped to each end. The wire colors were arbitrary but recorded on the schematic sheet so they could be duplicated in the rest of the octaves. Switches were taken from stock so they don't match.
Switches wired in place
Testing was done on the adapter board by connecting a Raspberry Pi Zero with the Tough PiAno software running. Some of the switches performed unreliably so hopefully the switches that were ordered are all functional when they arrive.
One octave of buttons in wood
A wooden base was built on three sides. The base will give everything room on the inside. It will be held to a wooden shelf underneath by using bolts from the underside which will couple into threaded wood inserts.
Wooden base built around button board
The rest of the weekly summaries have been arranged by date.
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This blog, including pictures and text, is copyright to Brian McEvoy.
This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.
All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.
All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.
Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim property or assets based on their post.
This blog, including pictures and text, is copyright to Brian McEvoy.
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