I wonder if anyone can help me with this simple problem I have as art of my school project..
I am trying to turn an electrical current on and off down a wire via a wireless signal on a key fob.
The cable is connected to a light. All I need to do is switch it on and off -remotely. Yes, I have seen remote light dimmers, but all I need to do is switch the light on and off (not dim) and make the circuit as cheap and easy as possible.
Can anyone tell me what the simple circuit diagram should look like, and what components need to be on the pcb etc?
Plus if anyone can - what the circuit in the key fob should look like.
"voodoochile" wrote in news:LaZvg.2076$ firstname.lastname@example.org:
If you can't do it already, how do you justify your insistence that it is simple?
Does it have to be secure from misfiring from other sources of signals? Does it have to work round corners or through walls, or are you ok with line-of-sight?
And JeffM, you're a moron, I have some sympathy with your reason for posting but all you seem to do is show up like a dumb policeman. Some things are worth it, like that apparently deliberate attenpt to infect people with Redlof virus in that other post, but if you're going to slap a newcomer in the face you might at least offer something contructive and on topic. You didn't even suggest he might cross-post instead of multipost, let alone have something to say about his subject.
"voodoochile" wrote in news:PA2wg.100$ email@example.com:
Ok I'll make the starting assumption that this is an educational thing to be a proof of concept, so the simplest possible answer is ok, you can see its weaknesses and move to better ideas from there.
(Btw, if you reply like this, below the quoted text, it's clearer. Unlike email, many people might answer, so this way it's clearer to read from top down.)
If you're switching a light, you can maybe get away with using light itself as a switch if the main light does not flood your sensor. The keyfob in this case need have nothing but a baterry, a switch, a resitor and an LED chosen for narrow viewing angle and high brightness. The sensor would be a phototransistor (to save you needing another transistor as a gain stage) with a coloured filter over the front to match the wavelength of your LED. The phototransistor output would trigger a bistable circuit to latch the off/on state, and output to a triac to control the lamp current. (That's assuming it's mains current you're switching, which could be a wrong assumption for a basic educational project, but never mind..)
Once you look for better ideas you'll want a pulse coded signal to eliminate false trigerring, or radio to allow indirect signal paths. Either of these are best handled with dedicated IC's, and I have no idea if this is permissible in your project. If it's required that you fully understand the logic and the part's behaviour, you might be better sticking to designs that use discrete components not IC's. If you figure out a neat way yourself, you'll learn more and probably get better grades from examiners, so long as you don't overlook standard methods already available to you.
William P.N. Smith wrote in news: firstname.lastname@example.org:
Yep :) They even make those in keyfobs, is what made me think of it.. Very nice simple idea. Does need the narrow beam though, and the narrowband light. That way you can use the intensity of the narrow waveband and a suitable colur filter to displace some of the difficulty of making filters in electronics. The main problem is that you'd need a very narrowband dichroic filter to make the simple idea effective beyond proof of concept, and that's costly, and more about optics than electronics.
Actually, he is replying to the existing post, the reference line does list the original message ID.
But, he doesn't keep the original subject in the header, so it can look like he's starting new threads. I find that annoying, at the very least because it's not immediately clear which post he is replying to. I thought the proper way of doing it was to put in a new subject, but include the old, such as Spam (was: newbie question) or something to that effect.
Then one knows the original thread just by looking at the subject header, and it's clear he is making a point about the original post rather than just posting nonsense (that it can look like to those who are unaware of what he's doing). I think it's also clearer about what's gong on. Announcing that something is spam or shouldn't be cross-posted, well it's too late for the original post. But it might help the newcomers, at least the ones who actually read the newsgroups before posting, because then they'd learn that such practices are at the very least frowned upon. Otherwise, it's too easy for them to take the bad practices of some as example.
If someone wants to punish the original poster, then it can all be done simply by reporting him. The point of making it public is to try to limit further practice by others, and I don't think the removal of the original subject from the reply helps this process.
He's also be in a far better position when he's announcing spam if he included a link to Mark Zenier's guide to the hierarchy, ftp://ftp.eskimo.com/u/m/mzenier/seguide9706.txt because that well explains where ads are supposed to go.
Valid point. My thinking that everyone views in a threaded manner is a dangerous assumption. I guess there are also some newsreaders that don't keep threads together when the Subject line changes. (The original Google Groups was notorious for that.)