Build a self-contained Dial-a-Song using a Western Electric 2500DM telephone and a Feather RP2040 + mono amplifier. People can dial a number to hear a song or message played through the handset earpiece. The CircuitPython keypad library makes it simple to read the Touch Tone keypad matrix.

It's a fun conversation piece -- especially with its accurate dial tone, touch tones, and other teleco messages -- and perfect for escape rooms or other puzzle games.

I'm not going to tell you how to live your life. However, should you choose to put some They Might Be Giants songs on there, you'll be a hero.

Parts

Angle shot of Feather RP2040 prototype
A new chip means a new Feather, and the Raspberry Pi RP2040 is no exception. When we saw this chip we thought "this chip is going to be awesome when we give it the Feather...
$11.95
In Stock
Double prototyping feather wing PCB with socket headers installed
This is the FeatherWing Doubler - a prototyping add-on and more for all Feather boards. This is similar to our
$7.50
In Stock
Angled shot of Adafruit Mono 2.5W Class D Audio Amplifier.
This super small mono amplifier is surprisingly powerful - able to deliver up to 2.5 Watts into 4-8 ohm impedance speakers. Inside the miniature chip is a class D controller, able to...
$3.95
In Stock
Lithium Ion Polymer Battery 3.7v 2000mAh with JST 2-PH connector
Lithium-ion polymer (also known as 'lipo' or 'lipoly') batteries are thin, light, and powerful. The output ranges from 4.2V when completely charged to 3.7V. This...
$12.50
In Stock
Euro-Style Terminal block with 4 pins
Connect this to that without soldering using these quick terminal blocks. They allow connecting of two sets of four wires together using just a flat-head screwdriver. These are...
$2.50
In Stock
Top view of a clear plastic storage box opened up with several compartments of variously sized wire ferrules.
Crimping's not just for 80s hair metal bands! When your project requires repeated insertion and removal with minimal strain, why not check out the reliable wire...
$17.95
In Stock
USB Type A Plug Breakout Cable with Premium Female Jumpers
If you'd like to connect a USB-capable chip to your USB host, this cable will make the task very simple. There is no converter chip in this cable! Its basically a...
$1.95
In Stock
Bundle of Premium Silicone Covered Male-Male Jumper Wires - 200mm x 40
These premium male-male jumper wires are handy for making wire harnesses or jumpering between headers on PCBs. They're 200mm (~7.8") long and come loose as a pack of...
$9.95
In Stock
Angled shot of 25 Through-Hole Resistors - 220 ohm 5% 1/4W.
ΩMG! You're not going to be able to resist these handy resistor packs! Well, axially, they do all of the resisting for you!This is a 25 Pack of...
$0.75
In Stock
Angled shot of 25 Through-Hole Resistors - 1.0K ohm 5% 1/4W.
ΩMG! You're not going to be able to resist these handy resistor packs! Well, axially, they do all of the resisting for you!This is a 25 Pack of...
$0.75
In Stock

You'll also need a 2.2µF electrolytic capacator for the RC noise filter circuit, although in a bind you can use this 10µF one.

Western Electric 2500DM Telephone

The classic! Grab a vintage Touch Tone phone out of your attic/basement or hit a flea market or yard sale. In a bind, you can find them on an online auction site for a reasonable amount.

Some older phones will come with a mechanical switching matrix, in which case you'll need to get a "newer" (early-1980s) electronic keypad, such as this one.

I haven't opened up the modern Cortelco ITT 2500, so I can't say if it can be wired the same way the older phones could.

This guide was first published on Feb 25, 2022. It was last updated on 2022-02-25 11:11:35 -0500.

This page (Overview) was last updated on May 24, 2022.

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