From: John O
Subject: TX/RX Pair
X-Newsreader: Forte Agent 1.92/32.572
NNTP-Posting-Date: Sun, 19 Jan 2003 05:53:23 GMT
Organization: AT&T Broadband
Date: Sun, 19 Jan 2003 05:53:23 GMT
I have a need for a design/schematic, for as very simple, as simple
and inexpensive as possible, transmitter and receiver "pair".
The application is very short range, under 20 feet, the transmitter
would need to send a simple as signal as possible every second while
it is on. The receiver, upon getting the transmitted signal would
reset a delay circuit. If a transmission is not received in say 5
seconds, the alarm is triggered.
There would only need to be one pair, one frequency, and no real data
other than the carrier and the ability to detect it and reset the
I have found no end of kits in the 30-50 dollar range for each side
and that is more then I want to spend. This does not have to be very
precise at all, just as long as the transmitter can have a 20 foot
range, and the receiver can get it and reset the delay.
I have everything but the cheap low power transmitter/receiver pair
worked out, I have seen some pcb's that seems to have transmitters
made of just a hand full of parts, under a dozen. I don't need a pcb
for it, just a schematic, and one that someone knows works...
Any idea where I might find some simple circuits for this kind of
application, it would also be good if these used generally available
parts that can be ordered from internet parts shops. No SMT, ideal
operating voltage, 1.5-3VDC, temp range 40F-100F.
I need to do the whole shootin match for about $20.