RE: RE: Nigel Orrs IR and Ians PC circuit

[Stuart Whyte <lists@xxxxxxx>]

Rob

>From memory I thing it is the rts line from the serial port.  This goes
through a resistor to a transistor.  The output from the transistor goes to
the bus line on the ir circuit.  You must also common the grounds on the
other side of the transistor, the serial port and the IR circuit.

Hope this comes out ok:

Transistor		IR
Circuit

/-------------Bus
/
Serial port(RTS)---------resistor---------
\
Serial port(Grd)---------------------------\-------------Grd

HTH

Stuart


-----Original Message-----
From: Robert Chasmer [mailto:robert.chasmer@xxxxxxx]
Sent: 25 April 2003 12:10
To: 'ukha_d@xxxxxxx'
Subject: RE: [ukha_d] RE: Nigel Orrs IR and Ians PC circuit


ian.bird@xxxxxxx wrote:
> Your current board(s) will have a power supply somewhere to make them
> work. This power supply gives the bus power and the TSOP's simply
> grounds  or doesn't ground this bus. The bus is connected to the 555
> chip which is turned on and off depending on the bus state.
> The PC connection simply emulates the TSOP. From the serial port
> one of the connections is used to feed the base of a transistor
> (switch) through a resistor and this switch grounds or otherwise
> the bus.

Stuart/Ian thanks for your replies.  I think I understand nigels circuit
and
what the TSOPs do.  The TSOPs pull the bus low during IR activity, and so I
need the serial port to do the same thing.  But could I have a little more
detail please on how the serial port will act like a TSOP.

The IR sender circuit I have already has transistor switch feeding the
trigger on the 555 timer as per Nigels diagram
http://www.geocities.com/nigelorr/ir_extend.html.
 So coming out of the
serial port do I need an additional transistor switch, and what pin on the
serial port is supposed to feed it (Is it pin 3 Tx?).  A little diagram
showing what components to use and how to connect them up would be a great
help.

I think my main problem is the limited electronics knowledge I have is all
mixed up and wolley.


> The only common connection is ground which has to be connected
together
> so both devices are batting on the same 'ground' (excuse the pun).

:-) Ok, my bus consists of +12v, signal, 0v.  Each reciever/transmitter
circuit can have its own power, but they need to share the signal and 0v.


Rob

I feel like I need to go back to school and learn all about electronics
again.  It all seems like years ago... well it was :-(

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