Introduction: Electrify Your Tap-A-Tune Piano
Create experimental punk music and horror movie sound effects with this project inspired by Randofo’s "Electric Cigar Box Guitar" Instructable and EvanKale’s "Electric Ukelele with Tone Control” Instructable.
The tap-a-tune piano is a classic toy instrument for toddlers. Despite only having four keys several tunes can be played on it - “Mary Had A Little Lamb”, “When The Saints Go Marching In” and even “Today” (by the Smashing Pumpkins).
Step 1: “Anatomy and Physiology” of a Tap-A-Tune
- The tap-a-tune is played by pressing keys. Each key pushes up a metal pole which hits a corresponding metal bar creating the musical note.
- The above pictures show the tap-a-tune pulled to pieces as you can see there is plenty of room in the body to add modifications.
- The body of the tap-a-tune doesn’t play a role in amplifying the sound.
Step 2: Gather Your Stuff
- Tap-A-Tune piano - My 5 year old daughter has had one since she was a baby and I wanted to breathe new life into the instrument
- Amplifier - Inspired by the Jelly Jar Guitar Amplifier Instructable but lacking the tools and equipment to make holes in glass I built a simple 0.5w amplifier in a $AU 1.50 "keep cup"
- 3.5mm to 3.5mm mono cable
- 4 x piezo transducers - one for each note
- 2 x A1M (1 Megaohm logarithmic) potentiometers - You could probably use any potentiometer >200KOhms for the volume control
- Potentiometer knobs
- 22nF ceramic capacitor - chosen because it was the only capacitor in the nF range I could find lying around
- “Experimenter’s board” for mounting capacitor - I was thinking about adding other components to change the sound but didn't end up doing it, you'll see I have some resistors in the picture, these weren't used in the final instrument.
- Lead free solder
- Rubber bands
- Soldering iron
- Something to cut potentiometer shafts to size - A hacksaw is recommended but I didn’t have one so I used a pair of bolt cutters
Step 3: Prepare Tap-A-Tune Case
- Drill hole for mono socket
- Drill hole for volume pot (A1M)
- Drill hole for tone pot (A1M)
- Drill two small holes in white panel for transducer wires
Step 4: Fit Pots and Socket
- Check socket and pots fit
- Cut pot shafts to length
Step 5: Prepare Piezos
- Using wire cutters carefully remove piezo discs from their plastic casings* - For the piezo to work as a pickup it needs to be in direct contact with the sound source (ie metal bars).
Step 6: Electronics
- Mount capacitor* on board as shown
- Ignore the resistor in the picture I was experimenting - the resistor is not required
- Wire up as per diagram
*If you look closely at the picture you’ll see a 222 code on the capacitor - I realised my error on the first test run and overcame the problem by adding a 223 code capacitor in parallel to the 222 code capacitor (Ctotal = C1 + C2)
Step 7: Assemble
- Place board in base of tap-a-tune
- Fit pots and socket
- Add knobs to pots
- Ensure wires aren’t interfering with the keys
- Pull the positive and negative wires which will connect to the piezos through the holes in the white panel
Step 8: Piezos
- Solder the piezos in parallel - connect the red wires to the positive wire and the black wires to the ground wire
- Place one piezo on each metal bar
- Secure them in place with rubber bands (as pictured) - I tried taping them down, gluing them down and even blu-tack but found the rubber band method created the best sound
Step 9: Plug and Play
- Plug the tap-a-tune into your amplifier with the cable
- Tap away
- Adjust volume
- Adjust tone
- Kids it’s time to irritate your parents!