Meowsic Keyboard Output Jack

When Wilgubeast told me about the supremely annoying Meowsic Keyboard that played cat meows instead of tones, I knew I had to have one. Two days before Christmas I obsessively tracked it down to Target. I then obsessively visited five stores overrun with tumultuous hordes of holiday shoppers until I finally found a store that still had 3 in stock. I snatched one and headed immediately for the register. The checkout clerk, assuming this was surely a gift for a small child, asked if I wanted a bag in which to hide it. I told him it was not necessary. I knew the truth. I was a grown man buying a meowing cat keyboard with the intent of modifying it to play loudly through a distortion pedal during an underground rock show at Frenzy's house in Oakland.

The show went about as well as one might expect it would when someone is playing a meowing cat keyboard through a distortion pedal and a megaphone. We tried people's patience. I think our band may only have 8 lives left.

Nonetheless, I would be remiss if I didn't show you how to add an output jack and volume knob such that you too can use it to make a terrible racket at underground rock shows in Oakland.

Step 1: You Will Need

Go get stuff:

- Meowsic Keyboard
- 100K potentiometer
- 100K resistor
- 10uF capacitor
- SPDT toggle switch
- 1/4" mono jack
- A knob
- shrink tube (or electrical tape)

Step 2: Open

Open up the Meowsic Keyboard and make sure not to lose any of the (many many) screws.

Step 3: Drill

Drill a 3/8" hole in the top of the cat's head for the 1/4" jack.

Drill another 9/32" hole about an inch to the side of the first hole for the potentiometer. To keep the potentiometer from spinning in place, it helpful to drill another 1/8" hold just to the side to catch the little mounting tab.

Finally, drill a 1/4" hole about an inch to the side of the potentiometer for the SPDT switch.

Step 4: Wire It Up

To make the circuit, you will have to cut in half the wire that is connected to the + terminal on the speaker. The half connected to the circuit board will be extended and connect to the center terminal on the switch. The half connected to the speaker will be connected to one of the outer terminals.

The 100K resistor will bridge the outer terminal of the switch to one of the outer terminals of the potentiometer. The other outer terminal of the potentiometer will be connected to ground from the keyboard's power supply.

The positive side of the 10 uF capacitor connects to the center terminal of the potentiometer and bridges to the signal tab on the audio jack (where the negative terminal connects).

The barrel of the jack also connects to ground.

For more info, check out the schematic in the final picture of the series. To learn how to read schematics, check out the Basic Electronics instructable.

Step 5: Clean Up

Glue any loose components in place with hot glue and cover up any exposed electrical connections that may shift about with electrical tape.

Step 6: Case Closed

Refasten all of the screws that you loosened earlier.

Step 7: Knob

Finish it up by affixing a knob to your potentiometer.

Step 8: Rock

Take your keyboard, gather your bandmates, go forth, and make a terrible racket at underground rock shows.

Pictured is the band AIDS Walk (trying to look serious) moments before making a terrible racket.

Comments

[guzmanpaco]

Hi I recently built this and the sound output on the mono jack is very very low. Like I have to put max gain on my audio interface and max volume on the potentiometer and keyboard.

This results in buzzing sound on like Ableton. Anyway to fix it? Like the sound is mostly buzzing sound and the audio from the keyboard is barely audible.

I checked middle of switch gets like 1.65 - 1.85 v but middle of potentiometer gets 0.12-0.24 volts regardless of pot. Any idea why voltage levels are so low?

Thank you

edit:

I think the potentiometer had weird issues. I ended up just doing a basic volume circuit with another 100k potentiometer and all the issues disappeared.

[randofo]

Yes. My suggestion was going to be to try a new potentiometer. Glad it worked out. :)

[Ok Housecat]

What is the purpose of the capacitor?

[randofo]

It is a filter. Keeps unwanted signals out of whatever you are plugging it into.

[randofo]

Probably not necessary, but I put it to be safe.

[theghostseeker]

Would be cool if you made an instructional video of the process.

[Guyitsme]

Hey there I’m new to this will any 100k resistor work? I ordered the one featured in the picture below, and I wanted to ask before I soldered it in and blew something up lol thanks!

[randofo]

Those should work.

[Guyitsme]

He’s a pic of it helps

[randofo]

Maybe double check your potentiometer with a multimeter and see that it's working properly. The only part responsible for controlling the volume is the potentiometer. If the signal is making it through unaltered, it is likely not the other components.

[Guyitsme]

Ok thanks Soo I put it all together, and it all works, except for the volume knob makes no difference in volume when I turn it, do you have an idea to as to why that could be?

[randofo]

Is the capacitor connected the center pin on the potentiometer? It does not appear to be.

[Guyitsme]

Sorry the first pic was a bad angle, I t’s not a huge deal cause like I mentioned everything else works, the switch and all, and I can adjust the volume with my amp, I was just wondering why everything else works and not the volume, I ran a extra ground from the pot to the power supply to get rid of the extra hum I was having! That’s what the extra wire is if you were wondering

[MohiniO]

Hi randy greetings from the Philippines, I am currently enrolled in your Electronics class because of this 80pesos (1.58usd) Doraemon toy piano I found I was hoping to try learn circuit bending stuff and then found out that this has no bending points and someone in reddit advised to voltage starve and another one advised to just put output to effects. And I did not know where to start and realized needed to learn the basics first. Anyways just getting itchy to do something with this as practice. That is why, I was wondering if it is possible to do this instructable for this piano? If yes, it is possible, then this will be my first electronic project.

If yes Questions:
1. (uses x2 AA batteries) will the values of the potentiometer, resistor and capacitor change?
2. i dont know why but can i replace the speakers if it breaks? (or will the output jack ignore the existing speaker here?)

Thank you for your efforts in teaching these amazing things, been scanning through all your Instructables when i was searching for the Electronics class projects

[randofo]

It should work. The values should theoretically be the same. If it is too quiet, you can try lowering the value of the resistor a little bit (maybe drop it to 47K and see what that does).

You won't break that speaker unless you hit it with a hammer (or something similar).

The potentiometer is basically working as a voltage divider. The resistor is making sure the voltage divider never goes to a value of zero resistance. You can learn about voltage dividers here:
https://www.instructables.com/lesson/Resistors/

The capacitor is filtering out any unwanted noise that might find its way into the audio signal. You likely don't need to worry about that doing anything bad.

[MohiniO]

I think i broke something it is not working anymore or maybe my soldering is bad? I got the wrong toggle switch (spst instead of spdt) so i had to wait till i got the right one and while waiting i changed the original wires so they are all the same since it was super thin one thin piece inside insulation.

[randofo]

My best guess from the pictures is that you broke the terminal on the speaker where the black wire is connected. I would test it for continuity with a mutlimeter (if you know how). Maybe try adding more solder to bridge the terminal where it seems to have cracked. If that doesn't work, you could possibly try replacing it with another small speaker and seeing if that helps.

[MohiniO]

Thank you for your time, this is very encouraging, to keep moving forward without getting scared, will work on this today, i got the stuff needed at a local electronics components shop (can buy these stuff per piece here), hehehe, so nervous and excited about this. ))

Will read the resistors lesson right now, just finished reading the switches in your electronics class 2 days ago and had to rest a few days.

[Mikkel Just]

Hope this can help you figureout what i did wrong

[Mikkel Just]

And from another side