Instructables

Wireless doorbell Morse Code transmitter and printer

Picture of Wireless doorbell Morse Code transmitter and printer
Morse code copy.jpg

In this instructable, I will show you how to modify a wireless door bell into a Morse code transmitter and receiver. Also, I will show you how to make a real time Morse code printer using simple parts.

Background information:

Morse code was developed since late 1830s. It encodes letters and numbers into sequences of short and long signals called “dots” and dashes”. Morse code is used in electrical telegraph system at the beginning, and later it was adapted to radio communication.  Today Morse code is still using in military, ham radio communication, dire emergencies, etc. Morse code is an old-school way for long distance communication, and it is very easy to learn.  You can send encoded messages to your friends in a fun way.

Step 1: Transmitter:

The door bell I have is from ebay (~$5, 100-meter range). There are some advantages using wireless door bell as sending/receiving unit:
A. Low cost and easy to find.
B. It has pretty good transmitting range.
C. The frequency of transmitter and receiver are preset, no adjustment is needed.
D. Low interference.

Just for fun, I make a telegraph key using a wooden spring type clothes clip, two M3 screw nuts, one M3X8mm screw and one M3x12mm screw, two M3 washers, a couple pieces of hook up wire, some double-sided tapes, and a piece of plastic board. (picture 1)

Pull the clothes clip apart, then place two wooden pegs together and dill a hole.  The hole should be just a little bigger than the screw you use. Use a smaller drill bit to drill a hole near the corner of the plastic board, and use M3 screw tap to tap the hole. (picture 2 and picture 3)

Put a small piece of double-sided tape on one wooden peg. Bond the peg on the plastic board. Overlap the hole on the peg and hole on the board. Use the screw to clamp down a piece of hook up wire. (picture 4 , 5, and 6)

Similarly, clamp down another piece of hook up wire on the other peg with screw and nut. (picture 7)

Put the clothes clip back together. Now the telegraph key is finished. It is acting like a momentary push switch. (picture 8)

Open the back cover of the transmitter. Take out the circuit board. Drill a small hole on the side of the enclosure for the telegraph key and buzzer wires. (picture 9 &10 )
 

The transmitter is using 12VDC. I use RadioShack (073-259) 76dB Piezo Buzzer to add sound effect. Locate the power switch pins on the transmitter PCB, solder the telegraph key wires parallel to the power switch pins. Also, solder the buzzer wires parallel to the transmitter circuit after the power switch. (picture 11 &12)

Use double-sided tape to bond the transmitter and the buzzer on the plastic board. Now the modified transmitter is finished. Don’t forget to install the battery. (picture 13 &14)



 
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So does this transmitter/receiver only work over 100 meter distances? Do you have any edits that could be made to make it function over larger distances, RE: hundreds of miles?
cool project! you say that the doorbell is also a morse code receiver? does this mean that the morse code triggers the ringing of the bell? why do you need the piezo buzzer then?
bbsbb (author)  amandaghassaei2 years ago
Thank you. You are right. The Morse code triggers the ringing of the bell. The doorbell I have only plays music. I have to replace the ringtone IC with a piezo buzzer in order to get the beeping sound.