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Cheap remote ignition device

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DrZoidberg

Sun Dec 23 2007, 06:17PM

Registered Member #350 Joined: Mon Mar 27 2006, 05:14PM
Location:
Posts: 106

I searched for some information and found that apparently nowadays there exist ICs for just about anything.
Look at this site

It describes how to build a remote control with a microcontroller.
But you don't need a uC.
The site also says it's easy to build one without a uC if you use an encoder/decoder IC.
The data sheet for one of the those ICs is here

I don't have any experience with those ICs but as I understand it you can connect that encoder/decoder IC to either a radio, ultrasonic or IR modulator/demodulator IC.
Now you just need to do some more searching and find all the ICs you need and some instructions how to connect them together. I can't do all the research for you.

uzzors2k

Sun Dec 23 2007, 08:47PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

Shaun wrote ...

As for infrared itself, would that be screwed up by sunlight? I had an old lasertag set when I was little that wouldn't work or worse, would falsely trigger, in bright sunlight.

Usually one sends IR signals on a 36-40 kHz carrier so ambient IR won't trigger anything by accident. Of course if there is too much background IR, from the sun for example, it can flood the receiver's sensor. Come to think of it, ultrasonic might be the best solution. It can be implemented as easily as IR, and in fact I might just try that instead. It would eliminate the line-of-sight problem one has with IR. Does anyone know what kind of range ultrasonics can be used over?

Have you done much PIC programming? I can give you the mikrobasic/assembly source files if you want to use PICs for encoding/decoding.

cbfull

Sat Dec 29 2007, 01:41AM

Registered Member #187 Joined: Thu Feb 16 2006, 02:54PM
Location: Central Ohio
Posts: 140

While I do like the idea of using a wireless transmitter for remote ignition, many years ago when my grandfather and I used to fill balloons with acetylene/oxygen, I used a neon sign tranny and a long coax. It turned out that that capacitance of the coax wire itself made the sparks a bit more intense.

I always plugged the balloons with a 2 hole stopper, one end had a post through it for sticking in the ground the other hole fit the coax wire perfectly. I will admit that the coax wire we used should have been longer because I felt the blast wave from that every single time. I just put a 120V momentary switch on the transformer input to trigger it.

I don't know much about remote starters for cars but maybe that's worth looking into?

Shaun

Sat Dec 29 2007, 05:11AM

Registered Member #690 Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616

Acetylene/oxygen mix huh...I can't imagine how loud that must be. I've seen the old chemistry demo where you light a balloon with ONLY acetylene in it and the incomplete combustion releases flakes of carbon, but thats not even too impressive to begin with.

Back on topic... I was doing some more searching on the internet about this, and in spite of all the good suggestions about using IR and ultrasonic, I was checking out places to buy RF modules. I'm sure a lot of people know what these are; its basically a transmit or receive "IC"; the simplest ones having only 3 pins: Vcc, GND, and Tx/Rx

Unfortunately the places that will sell less than 50 of these things are very expensive, usually between $20 and $50 apiece.

I already have one of these (except I got mine for one third that price from a different website). It hadn't occurred to me to use this because there is a sizeable delay between button-push and relay-trigger, plus 2 of the relays don't work anymore.

It has an RF module on the board, as well as decoders an even drive electronics for the relays. I'm going to do some tests on it to see is the delay can be reduced, and swap out the relays for faster SCRs.

I think the delay might be because it it using a somewhat complex rolling code generator. After all, I believe these are intended for garage door openers and remote car starters.

Worst comes to worst, Ill just take out the RF modules and use them to build my own SCR/decoder board.

Bjørn

Sat Dec 29 2007, 05:39AM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

I think Futurlec has RF modules for $5.90.

I don't think cheap and safe works well in this context. Unless you are willing to spend it is never going to be completely safe. Remember, it is not safe until it has been testet 100 times more than it will ever be used and in 1000 different and unlikely ways.

TheMerovingian

Sun Dec 30 2007, 01:10PM

Registered Member #14 Joined: Thu Feb 02 2006, 01:04PM
Location: Prato/italy
Posts: 383

Exactly here

But consider using a microcontroller to filter spurious signals transmitting a precise code accross the air. You don't want that a model RC plane used in range makes go off your display in your face...

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