View Full Version : 1.0 mhz crystal projects ?

Areal Person
08-29-2007, 07:11 AM
Here is a really fun/simple crystal transmitter for the serail port on a computer.

I would like to do somthing like this with my Propeller in place of the computer.
But I'm a newbe at electronics.

Can I ? I don't know much about electronics.

Could I use the 5.0 mhz crystal ? This 1.0 mhz crystal has three pins ?

How can I make my propeller do some of this really simple & cool stuff ?


I have a tree growing out of my head, but

what do you expect ? I'm a programmer.

Post Edited (Areal Person) : 8/29/2007 12:25:26 AM GMT

Mike Green
08-29-2007, 07:37 AM
First of all ... read the instructions. What's pictured is not a crystal ... it's a crystal oscillator ... a combination of a crystal and some circuitry around it to make it oscillate. Note that it's set up to attach to a 9-pin serial connector which is normally attached to an RS232 port. The signal there goes between maybe +5V to -5V which a Propeller can't do by itself.

The Propeller can generate the radio signal all by itself (that's how it can broadcast a video signal on channel 2, 3, or 4 using the video output. Have a look at the frequency synthesizer object in the Propeller Object Exchange. Pick a frequency to output at and attach a short wire to the output pin you're using. You should be able to pick it up on a receiver. The Propeller doesn't produce a clean signal. You need a tuned circuit for that. Search the Wikipedia for "tuned circuit" and "parallel resonant tank" for examples and discussion.

Areal Person
08-29-2007, 07:49 AM
Cool, Thanks Mike.

I have a tree growing out of my head, but

what do you expect ? I'm a programmer.