>
>PICers - i'm looking round for ideas to build an IR modulator cct. did a
quick
>google but mostly fopund IR receivers.
>

I used to use a 555 design, see
http://www.geocities.com/nigelorr/ir_extend.html

I've moved it onto a 16f628 now, using the internal PWM to generate the
38kHz, gated in software when a demodulated IR signal is received on the
interrupt pin.  At some point(!), I will update the page with the '628
design, but it is trivial (from memory, load the PWM with the required
modulation frequency, then turn PWM on and off when the interrupt pin
changes state, you could just poll the demodulated data pin instead, if the
PIC isn't doing anything else).

The circuit consists of the PWM driving a transistor current sink, with a
visible LED in series with the IR LED to verify that it is working.
Approximately 7 external components (5V regulator + 2 caps, 1 resistor, 1
transistor, 1 IR LED, 1 visible LED).

I use it to control A/V equipment from multiple rooms (TSOP1838 receiver in
each room), and it works well.  The 555 worked fine too, but I hope to add
some simple contention handling to the PIC design.

Nigel
--
Nigel Orr, Design Engineer                 nigel@axoninstruments.co.uk
Axon Instruments Ltd., Wardes Road,Inverurie,Aberdeenshire,UK,AB51 3TT
               Tel:+44 1467 622332 Fax:+44 1467 625235
                   http://www.axoninstruments.co.uk

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body