MadModder
Gallery, Projects and General => How do I?? => Topic started by: John Hill on November 15, 2011, 08:04:34 PM
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We have a dozen or so DVD players around the exhibits in our little aviation museum and it is a real pain starting them all when the museum opens.
As you might expect these exhibits are in a hangar type building and my basic idea is to put 'something' in the roof of the hangar that will start the DVD players. We have two types of player only (until someone gives us another, ha ha).
Can we put some sort of infra red floodlight in the rafters and modulate it with a PC to start all the players? What would the 'floodlight' be?
Alternatively could we run a wire pair around the hangar with IR diodes near the individual players and drive that with a PC?
We do have some software capability but first I would have to learn the format of the control codes.
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Thinking a bit out loud here, but what about opening it up and connecting leads across the "PLAY" button, then you can use anything with relay contacts to control them... maybe even X10 modules (over the power line) so you don't have to run any more wires around the place.
-Sparky
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what make are the players?
i have pic code for the most common ir command types somwhere.
if a central broadcast is impractical, how about indivual units (a pic + led) to start them as the power comes on?
Bill
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Thanks Sparky, I had not considered X10 operation, I would have to look into the price of that.
Bill, I dont know the makes, but obviously I can find out next time I go out there, thanks for the offer of the codes and I might come back to you on that.
I am really liking the idea of an IR flood light up high that they can all 'see' but I havent determined what sort of light would be required and how I could 'key' it.
John
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The IR that the player is looking for may not be just pulsed - I am told by a usually reliable source that the IR is typcially modulated at a moderately high frequency too. Filters in the receiver separate out that frequency, making the system more sensitive and immune to interference form other IR sources.
Must be a common frequency used by most makers though as 'universal remote controls' are quite common.
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I am really liking the idea of an IR flood light up high that they can all 'see' but I havent determined what sort of light would be required and how I could 'key' it.
John
Maybe you could use one of the existing remotes to key an infra-red floodlight by removing the led from it and using its connections to drive an amplifier of some sort, then take the amplified signal up to the floodlight via a cable.
Andy
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Rather than using a communication method to start play, you could possibly just connect a timer chip to pulse the play button after a few seconds from power on. Basically this would set play a few seconds after mains power is applied. Power for the circuit could easily be derived from the internal DVD player power supply.
This should be possible using very low cost components, and should also be fast and simple to install.
Best Regards
picclock
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The IR that the player is looking for may not be just pulsed - I am told by a usually reliable source that the IR is typcially modulated at a moderately high frequency too. Filters in the receiver separate out that frequency, making the system more sensitive and immune to interference form other IR sources.
Must be a common frequency used by most makers though as 'universal remote controls' are quite common.
He he, I have learned a lot today, I learned that the data modulates a 38khz carrier. Thats makes it impossible to modulate a filament type lamp though it would not be too hard to put a chopper disk on a mains synchronous motor to chop the light from a QH lamp, that would certainly get the 38khz infra red to flood the display space.
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Rather than using a communication method to start play, you could possibly just connect a timer chip to pulse the play button after a few seconds from power on. Basically this would set play a few seconds after mains power is applied. Power for the circuit could easily be derived from the internal DVD player power supply.
This should be possible using very low cost components, and should also be fast and simple to install.
Best Regards
picclock
Good idea but it is a bit more tricky than that, we need the play button then select the chapter required then set the repeat, but it is still worth thinking about, thanks.
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He he, I have learned a lot today, I learned that the data modulates a 38khz carrier. Thats makes it impossible to modulate a filament type lamp though it would not be too hard to put a chopper disk on a mains synchronous motor to chop the light from a QH lamp, that would certainly get the 38khz infra red to flood the display space.
John,
It's along time since I played with IR remote devices !
There are a few different carrier frequencies in common use usually between 35- 40kHz
You would need to use IR LEDs for the flood light, not difficult or too expensive, but you may need quite a few LEDs if it's a big hanger! It might even be possible to construct the unit as a passive repeater by using a different carrier frequency to send commands to the unit (would save a lot of wiring)
However, if you are going to have to send several common (e.g. 'chapter', '1', 'play') commands the main problem would be maintaining synchronisation between players; i.e. if one took too long to change to 'chapter 1' it might miss the 'play' signal or - nightmare scenario - the units have a play/pause button, 'cos you just know one will get out of sync.
If you need to send different chapter select commands to different machines, it just not going to work ( Although, Sony machines often have a selectable device number so multiple players can be addressed)
It may seem a silly question, but have you checked that the DVD machines don't have a auto-start/play function? It used to be a common feature on VCRs & cassette players for exhibition use.
Bill
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Thanks Bill, you have given me a few things to check on, I had thought of the synchronisation and hoped we could solve that by giving plenty of time between commands so that even the slowest machine would be ready for the next command, fortunately most of the DVDs have been made by one of our members and have the same program format/layout.
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As Bill says the first step is a IR LED spotlight. A few dozen soldered up in a group with drivers would be ideal.
Then I'd either go the PIC route or use a hacked universal remote. Some universal remotes have macro functions that allow you sequence commands. You could easily sequence the commands for a number of different DVD players.
To hack the remote simply remove the internal LED and use it to drive the drivers of your group.
Another possibility is that some universal remotes are RF and have a separate receiver module that switches the RF to IR - these receivers can usually drive a number of LED units, again you could simply plug in your 'spotlight' into the output of one of these modules.
With regards range, I'd expect several LEDS pointing in roughly the same direction to give a range better than 100 feet or so plus you can always 'overdrive' them to increase the range - given the low operating time I'd imagine you could overdrive them close to their peak current value which would increase the range significantly.
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Hi John
you could adapt a IR remote control extender
for example click on figure one in this link :-
http://www.siliconchip.com.au/cms/A_107822/printArticle.html edit - not sure where the print come from
John
http://www.siliconchip.com.au/cms/A_107822/article.html
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Thanks for the comments everyone! :beer: