Newbie Needs Some Help

Hello, I'm new to this forum. I have some high school electronics experience, and basic electronics tools: soldering iron, multimeter, adjustable power supply. I'm in the CNC field, and I'm working on a new project for one of my machines. Its a digitizing probe. The probe is a single NC switch, the probe detects a workpiece and tells the machine the current positions. The probe is usually wired to the machine controller via a 2 conductor wire. The machine controller is a windows based PC that runs a DOS program to control it. The probe is wired to the computer through the parallel port. The problem is, that it is bothersome to have this wire connecting the probe to the controller. In industrial probes, the machine controller and probe are connected by wireless RF. My plan is to come up with a small transmitter that will fit in the probe, and a receiver that will detect the opening of the switch (probe) and perhaps trigger a relay to open the circuit wired to the parallel port.

For this to work well, there has to be a few criteria.
The whole system must work very quickly, 1/4 second or less.
Has to work within a 15 foot radius.
Should be shielded from interference (less critical).

Ive found this circuit for the transmitter. My plan is to simply add the probe switch into the circuit. Then to have the receiver monitor the incoming signal and trigger the relay once the signal stops (probe contact, NC switch open). I don't know how practical it would be to use this transmitter. And I'm not sure how to detect when the signal is no longer being sent.

Thanks for any Advice, Its much appreciated.
Mike

Dear gun_mike..
I higly recommend to use TX-RX modules to transmit the data signals a distance instead of implementing such circuits.
Because, your working environment is very noisy and there are very large electrical surges, therefore simple transmitter and receiver circuits won't work..
The best way to transmit the data signals is to use ready to use digital transmitting and receiving modules.
If you seek google, I'm sure you'll find tons of such devices

Thank you BigBoss,
I've sourced out a few RF modules from Sparkfun.
From what I understand this requires the use of micro controllers if I'm not mistaken. I would rather use MCUs' if its possible.
The one I was looking into was "FM Radio Transmitter Module - NS73M"
in the pin diagram there is two labeled as
#12 LIN Left audio signal input
#13 RIN Right audio signal input
My thinking was, to create a analog audio signal and close that circuit with my probe switch. And send that signal into the NS73M for transmission to the receiver.


I have no idea what to do with the signal from there. Or how to translate that signal into something that would close a relay or gate allowing the computer to detect the tripped probe. If any one could give me a push in the right direction, I would appreciate it very much.

Thanks again for any help,
Mike

Yo can find the TX and RX modules which are compatible with data tansmission by aid of a MCU.The modul which you have mentioned above -as I understood- is for using audio signals,not data.
The moduls which I talk about, have DATA_INPUT and DATA_OUTPUT pins.So,by programming MCU,you may use ISM bands such as 433MHz with some modulation scheme like PSK or OOK etc.It's simpler and straightforward.

http://www.hoperf.com/rf_fsk/RFM12B.htm