newbie question

Hi guys,

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.

Reply to
voodoochile
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was: newbie question

voodoochile MULTI-POSTED:

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*-*-*-*-*-*-*-*-appear+*-proper-answer-*-*-*-given+much-easier-*-*-*-*-what's-going-on+*-frowned-on+*-correcting+*-polite-*-mention-*-*-*-*-*-*-*+Just-because-*-*-*-*-*-*-*-*-does-not-mean-*-*-*-*-*-*+*-Followup-To-*+*-*-*-too-lazy-*-*-*-*-*-appropriate-*+*-*-_perfect_-*-*-*-*+*-*-*-*-two-groups-*-*-aren't-*-different

Reply to
JeffM

"voodoochile" wrote in news:LaZvg.2076$ snipped-for-privacy@fe2.news.blueyonder.co.uk:

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.

Reply to
Lostgallifreyan

Thanks for the support.

Reply to
voodoochile

We need more details, what voltage, what current, and (as 'lost' pointed out) how robust it needs to be.

It sounds like this is something you have to build yourself, is that true? If not, there are lots of car alarm systems with keyfobs, and Radio Shack used to sell X-10 switches with small (RF) remotes.

Lots of ideas come to mind, 40KHz IR remote receivers, photocells, etc, but I cna't tell from here how applicable any of them are.

Reply to
William P.N. Smith

Hey, didn't you just say that in some other newsgroup?

Reply to
William P.N. Smith

Yes - he went and multi-posted his msg.

Ironic really.

Graham

Reply to
Eeyore

"voodoochile" wrote in news:PA2wg.100$ snipped-for-privacy@fe2.news.blueyonder.co.uk:

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.

Reply to
Lostgallifreyan

Aka: A Flashlight. 8*)

Reply to
William P.N. Smith

William P.N. Smith wrote in news: snipped-for-privacy@4ax.com:

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.

Reply to
Lostgallifreyan

No, he MULTI-REPLIED. There is a subtle difference.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
Reply to
Michael A. Terrell

How subtle is it when the reply as actually a new original post?

Reply to
Don Bowey

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.

Michael

Reply to
Michael Black

Good thoughts, thanks.

But S.E.D should be S.E.D.P.HP, where P= Politics, and HP= Horse Puckey.

Don

Reply to
Don Bowey

What's horse puckey ?

Graham

Reply to
Eeyore

To get all the valuable nuances of the term, you should watch some of the "MASH" TV series. It appears to be an old military expression.

Reply to
Don Bowey

Yup.

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.)

Reply to
JeffM

I've seen quite a number of those but don't recall the term.

Over here we do however sometimes talk about ppl talking 'horse manure' - similar ?

Graham

Reply to
Eeyore

Yes, that's it.

Don

Reply to
Don Bowey

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