Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

AM transmitter from clock oscillator

  1. Feb 13, 2010 #1
    I am having to ask this from lack of electronic components in my area, so, I want to ask if it is possible to make an AM transmitter (short range) using a clock oscillator? I believe it might be possible, but as the crystal is 32768 Hz, it makes sense to ask, what kind of receiver set should I make to receive 3.2 KHz? I have attached a file of a radio circuit from scitoys.com. For this receiver, I believe the only way you can help me is by changing the specifications of the tuning capacitor and the other capacitor in the circuit.

    Please help me complete this school project of mine by helping me use the minimal of components to make my transmitter from a clock's quartz oscillator and give the specs for the receiver.

    Attached Files:

  2. jcsd
  3. Feb 14, 2010 #2
    If your crystal is 32768Hz, then it is nearly 33kHz, not 3.2kHz, which an audio frequency. Even 33kHz is at the low end of the range of frequencies normally used for radio. To adapt your diode detector radio to this frequency you would need a tuning coil inductance of about 100mH for a tuning capacitance of a few hundred pF. Winding this on an air core might be difficult, perhaps a ferrite bar core would help keep the dimensions down.

    Unfortunately, this sort of receiver is quite insensitive. To minimise the potential for interference you should not have much transmitter power, so the range may be very short. In addition, at this frequency the wavelength is over 9km, so short wire aerials won't work very well. Actually, I doubt whether 33kHz is the most appropriate frequency for what you are trying to to. Depending on what you want to send, a frequency intended for remote control of models may be more appropriate, and less likely to lead to trouble with interference and possible legal issues.

    You must respect whatever regulations apply to the construction and use of radio transmitters in your country. For a school project, this is something you must discuss with your teachers. I suspect that other forum members will have more to say on this subject.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook