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I have a question. I want to build a rubberband with a led light receiver inside of it and a button transmitter that you push and the light blinks. Hopefully a half a mile radius? Is this possible and what would I need to begin this?
By transmitter do you mean that it transmits visible light, or are you talking about an IR led? Does it just blink while you hold the button or do you want it to stay on for a time period or untill the button is pressed again. If you want it to go a mile im guessing its an ultrabright led, and do you mean a mile of visibility at night? How light (weight) does it have to be and does it matter how fast it blinks? What is it meant to do when it recives light?
ok sorry about that, I want the wrist band to blink(for a min or less) when a button is pressed. The distance between the wristband and the button has to be able to work with a distance of a half mile im thinking.
Whatever would allow me to get the distance needed, the vision would allow someone to put this transparent rubberband on their wrist and it lights up. I know little about this. I was just thinking that the receiver would need a long antenna to be able to respond from a long distance. But I need something that can fit in this rubber band type wrist band and work. So whatever you think would work in that type of situation.
but you can buy cheap OOK transmitter modules. I got one from robotshop for $5, it gives the range in meters but its range works out to about 1/3 of a mile. Since you are only turning a light on and off the interference suseptability of OOK might not be an issue for you. Infact, on the bracelet you might only need the reciver, a power source and an led, posibly a transistor if the output of the receiver is too low. Since I already have the module I'll wire it up this way when I get home and let you know how it works.
It seems to kind of work at this point, but its getting late here, so I will work on it more tommorow tomorrow. It doesn't work perfectly, in the absence of a signal the receiver catches interference and the LED flickers like a candle. It can also falsely turn on from interference even when a signal is present, such is the nature of OOK modulation. It works pretty reliably right after a change (change from low to high or high to low input into the transmitter) But if one state is held it starts to flicker a little. Also, the range won't be nearly a mile (rated 300 feet). But this is an example, and I figure I might as well since I've been meaning to see what this low cost transmitter can do anyway.
Here it is just set up with an LED. I know you cant really see all of the details there, but I don't think a schematic is necessary because other than what is given in the data sheet for the transmitter, all I did was put a 3mm led with a 160ohm current limiting resistor from out to ground, and a push button with an 18K pull down resistor on the input of the transmitter.
Right now it turns the led on and off when you press and let go of the button, but obviously this is no test of range. Also after not pressing the button (or holding it on) for a few seconds the led starts to flicker, so you get high interference here when it doesn't have a reference. There may be other factors causing interference. I'm no pro at this. The other bit is just a 5V regulator feeding the bus of the breadboard.
I could draw it up, I just put it aside, cause I wasn't sure you were still looking. It has a range of only a few hundred feet and is only reliable in short pulses. This means that for your application you would need to make an interpreter that would take different sequences of pulses as a signal to turn on and off, like a garage door opener. But if you still want to use this as a starting point, I'll draw it up for you. How much experience do you have with electronics?
to be honest i have none but i am not letting me get discouraged by this.
I do security at a water park and every time I work I get parents coming up looking for their kids, they cant get in or they will have to pay, so they just wait outside. I figured that this kind of invention would be simple and perfect and a good way to make cash.
hmm, well, if you just use this transmitter, I think since it looses its reference point and starts wavering once the signal has stayed low or high for about 3 seconds, you would need to program a chip to interpret signals. You might want to go with a pre-made remote on-off set. That would simplify it and increase your range. This place has some stuff that might work: OEM Products - Pre-certified RF transmitters and receivers add instant remote control. but what you're trying to do will be somewhat difficult, making a receiver that works reliably and fits in a bracelet. If you still want that schematic I'll draw it up later, but you really can get almost everything I did from the dustsheets to those parts, available on the page I linked to earlier that supplies them. All I did was follow those schematics, and you'll need to read the data sheet to understand enough to adapt this to your purposes anyway.