Most doorbells just make a simple generic tone. But I thought that it would be fun to modify a door bell so that it has a customizable ringtone. That way you can set it to play music or custom greetings. You could make it to scream on Halloween and play carols at Christmas. So in this project, I am going to share with you how to add a simple recording module to a wireless doorbell.
Step 1: Materials
Wireless Doorbell (and required batteries)
9V recording module (RadioShack Model: 276-1323)
9 volt battery
Soldering Iron and Solder (optional)
Hot glue and hot glue gun (optional)
Step 2: Background: How the Wireless Doorbell Receiver Works
1. The Radio Receiver: This section filters and amplifies the incoming radio signal.
2. The Decoder Array: This array of jumpers is used to set either the device's tuning frequency or the security code on the IC chip. This helps to prevent it from interfering with other nearby wireless devices.
3. The IC Chip: The IC Chip monitors the incoming signal and detects when the button on the transmitter has been pressed. When the signal is detected, it sends a tone to the speaker.
4. The Volume Control: This is a simple transistor amplifier that uses a variable resistor to set the speaker volume.
5. The Speaker: The speaker is a plain 0.25W speaker. It is wired between the positive supply voltage and the volume control transistor.
Step 3: Background: How the Recording Module Works
Step 4: Remove the Original Speaker
Step 5: Prepare the Wires on the Receiver
Cut the positive speaker wire as close to the circuit board as possible. This leaves you with a loose piece of wire. Strip at least 1/2" of insulation off both ends. On the negative wire, strip off at least 1/2" of insulation from the free end.
Step 6: Connect the Receiver to the Recording Module
The negative speaker wire will be used to connect the receiver output transistor to the play pin on the recording module. One end of the wire is already connected to the output transistor. So we just need to connect the free end to one of the play pin holes that were mentioned in Step 2. You don't need to solder the wire to the recording module. You can make a good connection by just twisting the wires together around the board. To do this, Insert a few strands of the wire through one of the holes (the hole is probably too small to fit the whole wire). Then twist the strands of wire back together. As long as wires are tight, it should make a good connection and stay in place.
Step 7: Final Assembly
The recording module that I used was not as loud as the original tone. So if you want to make it louder you can replace the speaker on the recording module or use it as the input to powered computer speakers.
Since the play button also functions as a stop button, the playback will be interrupted if someone presses the doorbell multiple times before the tone is finished. You can fix this by adding a capacitor between the recording module's ground and play pin. This will also help prevent stuttered playback that may happen with some wireless doorbells.