Newbie in great need of help ! ! !

[HellasTechn]

How do they work?

To be honest i dont know.

I do know how radars calculate bearing and distance. but i doubt that bob will be interested

 

[bobwilmott]

I'm still very interested in basics. I've ordered a very cheap wireless doorbell (thank you for the idea, HellasTechn) with an alleged range of 150 metres, and I'll play with that to begin with.

BobK... also still interested in your "two cell phones and an app" idea, and I'd very much appreciate hearing from you if there's an existing app that I can buy, or if I'd have to write it ?

Bob

 

[donkey]

ok for me this is easier than you are making it... if ALL you want is to detect when something comes into range then you need a transmitter and receiver.
the transmitter can only transmit the distance you want and receiver only picks up within the distance you want.... then transmit all the time.... when its in range the receiver will work, out of range the transmitter won't work.
a simple FM transmitter might make that range and you can get that to play all sorts of music and tones you want with an MP3 player attached.
I am guessing that the item you are working on is top secret so I can't give more details than that as I can't tell how much more you require. I sincerely hope whatever this project is works for you

 

[KrisBlueNZ]

when its in range the receiver will work, out of range the transmitter won't work.

Many uncontrollable factors affect the range.

 

[HellasTechn]

Many uncontrollable factors affect the range.

So true. phisical obstacles also greatly affect distance.

Even military ESM (Electronic Support Measures) when calculating distance from a transmittion source often have huge deviations.

 

[bobwilmott]

Donkey.... it's so top secret that even the NSA doesn't know about it yet

Is a wireless doorbell a "simple FM transmitter", or is there a simpler/cheaper variety?

Is the thing on eBay (link above) another simple FM transmitter ? And could I make it work by just attaching batteries to the transmitter and receiver parts, and an on-off switch to the transmitter and a buzzer to the receiver ?

(If it would also need an Arduino or a Pi, forget it ! ! ! ).

Thanks,

Bob

 

[donkey]

Many uncontrollable factors affect the range.

completely agree. but having said that with a simple door bell how will it detect range?
the only way I can see that happening is 2 trancievers they constantly poll each other, detect the range and then make sound if under 200 meters. as OP doesn't want anything microcontroller like I think this solution might be easiest.
it won't give exactly 200 metres. it might give 150 or 300. but without microcontroller setup I don't see an easy way to do this

 

[KrisBlueNZ]

completely agree. but having said that with a simple door bell how will it detect range?

It won't! Not with any accuracy, anyway.

 

[donkey]

Donkey.... it's so top secret that even the NSA doesn't know about it yet

Is a wireless doorbell a "simple FM transmitter", or is there a simpler/cheaper variety?

Is the thing on eBay (link above) another simple FM transmitter ? And could I make it work by just attaching batteries to the transmitter and receiver parts, and an on-off switch to the transmitter and a buzzer to the receiver ?

(If it would also need an Arduino or a Pi, forget it ! ! ! ).

Thanks,

Bob

http://www.ebay.co.uk/itm/433MHz-RF...it-for-PIC-Arduino-Pi-UK-SELLER-/400832709617? was the item like this?
you need a micro controller for that to best of my knowledge


http://www.circuitstoday.com/200m-fm-transmitter is a simple FM transmitter circuit you can build. as said before range will NOT be exact. it can vary hugely depending on a myriad of things including whats between point a and b, other transmissions that blanket the area etc. using a $2 FM radio to pick it up is all that is needed. you can also try plugging an MP3 player up to it

oh and I reckon I know what this is for.... you are giving it to your boss as a key ring so you can tell when to pretend to work... don't worry I did the same thing lol

 

[bobwilmott]

Close. It's to warn me of annoying children at Christmas time

 

[bobwilmott]

Donkey....

Yes, the one at http://www.ebay.co.uk/itm/433MHz-RF...it-for-PIC-Arduino-Pi-UK-SELLER-/400832709617 is the same as the thing I was looking at initially. I ordered one the other day and it's just arrived. It's very small compared to the eBay pic! But if it also needs a micro controller - and assuming a micro controller means an Arduino or somesuch - that's way beyond my capability and pocket !

You mention a simple FM transmitter circuit and a $2 FM radio. Can you point me to eBay or other adverts for these two things, please ?

Thanks very much,
http://www.ebay.co.uk/itm/433MHz-RF...it-for-PIC-Arduino-Pi-UK-SELLER-/400832709617
Bob

 

[donkey]

bob I can send you a link but how will the kids activate it? are you attaching it to the kids?
do you have a door way they have to go through? is it inside or outside? how much do you want to spend?
the FM transmitter will NOT give a true distance measurement, but depending on where you want it to be there are a myriad of devices I can think of. the FM transmitter I was thinking of needs a MP3 player or some such to generate music to hear.
http://www.ebay.com.au/itm/like/360...2&ops=true&viphx=1&hlpht=true&lpid=107&chn=ps this is an infared item that can detect people walking through a door or gate area. if its outdoors I am unsure if it will withstand the elements.
there is a link I sent you before that has a circuit you can make that will act as a wireless microphone for the kids to play with.http://www.ebay.com.au/itm/New-Wire...rs_Headphones_Microphones&hash=item1e92fe6d62 this version I doubt will get close to 200 metres but its a start.
http://www.ebay.com.au/itm/LCD-Screen-MP3-Player-32GB-32G-Vedio-FM-Music-Media-Black-/231296951136?pt=AU_MP3_Players&hash=item35da5f6360 or http://www.ebay.com.au/itm/Mini-Poc...360762779076?pt=AU_Radios&hash=item53ff2325c4 will do as a receiver, or you do is leave it tuned to a blank station on FM band, when the little darlings come close the Static will start to disappear and you know they are in range..... as I said before it all depends on the transmitter
you can also use PIR http://www.ebay.com.au/itm/Automati...AU_Home_Personal_Security&hash=item338ee3f221 and instead of a light put a siren on it....
the list of ways to do this is extensive... just don't know the totality of what you need. also I don't know how you plan to make the darlings keep hold of the transmitter

 

[bobwilmott]

Superglued to their foreheads should do it
Thank you very much, Donkey, I'll have a good look at those links later.
I was only joking when I said it's to warn me of annoying children, but now I think about it......

 

[bobwilmott]

Same topic, but a New Question for the New Year... hopefully a simple question with a simple answer ! ! !

I've attached (if I pressed the right buttons) front and back views of the transmitter part of a wireless doorbell.

The problem is that when I press the doorbell button, it makes the ding-dong sound but only once. I want the transmitter to transmit, and the receiver to ding-dong, continuously.

I've tried everything that my layman's brain can think of... holding the doorbell button down, putting a paper clip between numerous combinations of the soldered bits on the back of the PCB, etc. Nothing I've done makes the ding-dong go continuously :-(

I'm guessing that the microswitch is a type that sends just a single pulse rather than a continuous one.

Does anyone know how I can achieve the desired effect ?

Thanks,

Bob

 

[HellasTechn]

What if you remove the button and attach a 555 wquare wave generator (really simple circuit) adjusted to produce say 1 pulse per second or less as needed ?
The circuit will perceive that as someone is pressing and releaseing the button all the time and will sound continiously.

 

[HellasTechn]

I'm guessing that the microswitch is a type that sends just a single pulse rather than a continuous one.

Bob

No it does not send a specific pulse. It is just DC voltage.
that the circuit is programmed to ignore the button for as long as it plays the sound.
It will then be ready to accept an other switch press after it has finished playing the sound.

 

[bobwilmott]

Thank you very much, HellasTechn, for your two messages. I'll research the 555 square wave generator and get back to you.
Bob

 

[bobwilmott]

OK, here is a better pic of the back of the transmitter.
I've looked at some 555 square wave generators on eBay. Is there a particular one that you would recommend on eBay or elsewhere (preferably from a UK seller)?
Thanks,
Bob

 

[HellasTechn]

I would recommend you to make one yourself.

All you need is a perforated copper bard, an LM555 chip, two resistors and two capacitors. You can get all theese for like 1$ or less (except the copper board) at your local electronics shop.

Or if you dont have the tools to do so (solder iron, solder, old pices of wire etc) you could get this one.

http://www.ebay.com/itm/Square-Wave...028?pt=LH_DefaultDomain_0&hash=item339b644d8c

Looks nice. then all you have to do is set the duty cycle potentiometer to a value of say 50% and the freq potentiometer to a comfortable level as needed.

from uk seller i dont see any.

 

[bobwilmott]

Thank you, HellasTechn, I will try to make it myself

I have looked on eBay and there are thousands of LM555 chips and resistors and capacitors !!! Would it be possible for you to recommend the best ones, please ?

I hope I'm not being too much of a nuisance.

Bob