Re: RE: Nigel Orrs IR and Ians PC circuit

[ian.bird@xxxxxxx]

Hi Rob

Stuart is spot on with his description. I can give you more detail but all=
=20
I will really be doing is saying the same thing in more words so here goes=
=20
anyway.

Your current board(s) will have a power supply somewhere to make them=20
work. This power supply gives the bus power and the TSOP's simply
grounds=20
or doesn't ground this bus. The bus is connected to the 555 chip which
is=20
turned on and off depending on the bus state. IIRC the bus is active low=20
meaning when the TSOP grounds the bus the 555 chip starts sending IR at=20
38KHz.

The PC connection simply emulates the TSOP. From the serial port one of=20
the connections is used to feed the base of a transistor (switch)
through=20
a resistor and this switch grounds or otherwise the bus. The only common=20
connection is ground which has to be connected together so both devices=20
are batting on the same 'ground' (excuse the pun).

Ian







Stuart Whyte <lists@xxxxxxx>
25/04/2003 09:36
Please respond to ukha_d

=20
To:     "'Robert Chasmer'" <robert.chasmer@xxxxxxx>
cc:     "UKHA (E-mail)" <ukha_d@xxxxxxx>
Subject:        [ukha_d] RE: Nigel Orrs IR and Ians PC circuit


Rob,

Not being electronically minded, I will try to explain as best I can, but
I'm sure Ian will be able to explain more.

The circuit that Ian built for me has a transistor switch controlled by=20
the
serial port.  This then puts a signal on the bus line and controls the TX
module.=20

The original circuits still need power.=20

HTH, but like I say, Ian's explanation will be FAR better than  mine. ;-)

Stuart
-----Original Message-----
From: Robert Chasmer [mailto:robert.chasmer@xxxxxxx]
Sent: 25 April 2003 00:56
To: 'ukha_d@xxxxxxx'
Cc: 'lists@xxxxxxx'
Subject: Nigel Orrs IR and Ians PC circuit


Way back in Dec 2002 Stuart Whyte [mailto:lists@xxxxxxx] wrote:
> Saturday morning saw the arrival of a jiffy bag containing a custom
> made circuit board from Ian Bird that allows me to connect my PC
> serial port to the IR signal bus of the Nigel Orr designed IR
> extender, that is already running through the flat.
> After a trip to Maplins, who (amazing as it may seem) had all=20
> the parts in stock to construct an IR Receiver circuit
> http://www.lirc.org/images/schematics.gif
to teach the PC my remote
> commands.

Stuart/Ian, I have Nigel's circuit running through the house as well. With
the arrival of a new PC at the beginning of the year I'm now ready to
connect it to the IR bus and finally have a play with Dans IR software.

I see the circuit connected to your PC has a TSOP which is for receiving=20
IR.
To inject IR on the bus for Nigel's sender circuit do you just connect=20
this
receiver in parallel with other TSOPs?.

The TSOPs I've used with Nigel's circuit are 1838's that I got from Keith,
rather than 1738's which I think have a slightly different pinout.  I've
found a very similar circuit to the one on lirc but that uses the 1838's,
with a good tutorial:-
* http://www.meblin.karoo.net/infrared.htm
* http://www.heatseekerz.net/index.php?page=3Darticles&id=3D4&pagenum=3D3=20

I think the idea is that this powers itself via the serial port, as
there=20
is
no mention of a separate powersupply.  So my question is to I only need to
connect the OUT (Pin 3), and GND (Pin 2) to my other circuits to do the
trick?

I've guessed at some maplin codes, I'm not sure if I got the right
components:-
Maplin                           Part  Description
VH06G/AT02C/DT55K                10=B5F, 16V (elco)               
Capacito=
r=20
=20
SC93B/YR75S/RA49D                100nF / 0.1=B5F           Capacitor
D4K7                                             Res 4.7K        Resistor
QL80B                                            1N4148  Signal Diode
QL26D                                            LM78L05ACZ      0.1A=20
Fixed Regulator=20

Do this look about right?


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