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'pic application'
1998\12\09@201604 by Adam Winsor

picon face
I want to make a control panel for a swithcing project to turn on lights fans
ect.  I also want it to have a IR sencer to tuen on a light on the panel so
someone can see the switches in the dark.  The lights, fans ect. run on DC
power

Adam

1998\12\09@215325 by Sean Breheny

face picon face
Hi Adam,

       I'm not sure to what level of planning you have taken this, but it would
help if you could make your question a bit more specific. How many
lights/fans do you need to control? Will they just stay on when switched
on, or will they need to be automatically turned on/off according to a
sequence or according to temperature or light conditions, etc.? The IR
sensor, you mean a passive IR detector to sense the movement of a person in
the vivinity of the control panel?

       If I follow your question correctly, it seems to me that you want to hav
e
a simple panel of ON/OFF switches which just control a small number of fans
and lights, AND you want this panel to have a light on it which will turn
on in response to the movement of an operator in the vicinity.

       If my interpretation is correct, then there remains one final
consideration: how much power do these lights and fans draw and how far
away are they located? In other words, do you wish to switch them directly
(just run DC power to the panel, thru the switch, and then to the fan/light
which it controls) OR, if the fans/lights are located far away (100s of
feet) or draw large amounts of power (>10 amps), then you may want to use a
relay to actually switch the light/fan, and control its coil by the small
switch on the panel.


       If you actually want to control MANY lights/fans from a small number of
switches and possibly want them to turn on/off in a sequence, etc, then a
PIC with a keypad would probably be the best solution. The PIC would have a
numerical keypad input, and you would have a number assigned to each
light/fan. To turn it on, you would punch in the number, and then hit "ON".
Punching in the number again and hitting "OFF" would turn it off, for
example. The PIC would also have a large parallel or serial "bus" of relays
(or even transistors, for very small lights) which it would address to
actually make this happen. Lots more info is available on this if this is
what you want.

       As for the light on the panel itself, this is easy. You can buy small
passive IR detectors (PIR) from many sources.

Try

http://www.ramseyelectronics.com
http://www.jdr.com
http://www.mpja.com

These will usually provide a relay which closes for several seconds when
movement is detected. You may be able to extend this delay to a minute or
however long you need and then just use it directly to switch the light.
Otherwise, you can use the signal which would normally drive the relay to
drive a one-shot multivibrator (a circuit which turns on for a given delay
time) to drive a relay which then drives the light. You could use a PIC for
this, but the venerable 555 or even just an RC circuit and a transistor
would be cheaper. You could also look into PIR controlled light fixtures
for houses. These are usually intended to run large power bulbs from AC,
but other than  that, they do exactly what you are looking for and are
probably readily available.

Good luck,

Sean


At 08:04 PM 12/9/98 EST, you wrote:
>I want to make a control panel for a swithcing project to turn on lights fans
>ect.  I also want it to have a IR sencer to tuen on a light on the panel so
>someone can see the switches in the dark.  The lights, fans ect. run on DC
>power
>
>Adam
>
+-------------------------------+
| Sean Breheny                  |
| Amateur Radio Callsign: KA3YXM|
| Electrical Engineering Student|
+-------------------------------+
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