Basic RF relay switch help wanted

[Toddie]

New member here.

I don't know why i did not google "electronics forum" before!
This is awesome!!!

I have never done an electronics project before but I want to make a simple "key finder".
It has to be extremely small though, and inexpensive to construct.

I want to operate the receiver on a button style battery. It will have 3 led lights and some sort of small audible device attached to it.

When the transmitter send a signal I want the receiver to activate the led lights and the audible device twice (just like a key finder) . I would like to have the range be 100 meters but I am flexible on that and just being hopeful.

I found an online electronics store that fabricates the boards for you but they seem like they have more functionality then I need for such a simple task and therefore more expensive. I like them because they are small but they are 9 bucks a piece plus shipping!

Here is what it looks like.

This tiny RF Receiver module is great for building your own wireless remote control or wireless link. Remote control that allows to control different devices can be easily implemented with wide range of encoder/decoder chips (such as HOLTEK HT12E + HT12D or MC145026 + MC145027 available in our store) or PIC / AVR microcontrollers. RF Module can also be used for sending data at up to 4.8KB/s.

RF Receiver Specifications:
TTL Compatible Output
Voltage Supply: 5V
Power Consumption: 5mA
Receiving Sensitivity: -103 dB
Max Transfer Rate: 4.8KB/s
Operating Frequency: 433MHz
Dimensions: 30mm x 14mm x 7mm


So basically has anyone else made a similar project and if not want to help and show me where can I get started? Thanks!

-Toddie

 

[OLIVE2222]

Hi Toddie,

Welcome to this forum!
technically you can use such modules to made a key finder.
The range will depend on many factors, however it' easy to try, the main caveat is the battery life. The receiver is 5V powered not close from standard batteries voltages. Such project can more successfully be buildup with 3V3 ICs , battery saving features (like sleep - receiving cycles). NORDIC made transceiver they can fit http://www.nordicsemi.com/eng/Products/2.4GHz-RF.
Olivier

 

[Toddie]

Let me be more specific.

Do you have a link to a "key finder" schematic that has already been published?
I require a basic blueprint of the circuit, how to assemble the circuit, and also a list of parts. Remember, I am looking for not only the smallest design possible, but also by constructing it myself I can save money. I just used the receiver pictured as an example reference for the size I am talking about. I am not thinking of using that receiver. I would like less power used as well as you mentioned.

Thanks!

P.S. I have looked on the web for a while and I dont know much about electronics but I am willing to learn how to construct this myself but It would take less time and money if I was to have some help designing this. I have not found any plans for something like this so I was hoping someone knew of some plans or could help me create some.

 

[jackorocko]

You are asking for a very specific design. Unlikely you will find what you want. Even if you find a schematic, you will need to design a pcb layout and choose your parts etc. It can get very complicated for someone completely new to the idea. Hope you are up for a challenge. You will also need a lesson in soldering surface mount components.

 

[Toddie]

The design is not very specific.

I want to use technology that is already used in every day electronics.
The amount of flashes, and sounds... are negotiable. I am more interested in simply the functionality.

Take for instance this wireless doorbell

I want something like this, but I do not need 16 melodies... And I do not need volume control.. and some other things. A person reviewing the wireless doorbell said it was * Very simple receiving circuitry. So I more or less want to reproduce a more simple version of this...

And I may be new to electronics, but I have soldered many things before. I more or less am new to designing circuits and boards. I have taken apart electronics before just never manufactured them.

 

[Toddie]

To calculate the pcb surface area I will first need some parts.
I know I need a transmitter chip. I need 3 light emitting diodes, but those will not be mounted on the board itself, I just need a place on the board to connect the leads. l.e.d. flash built in would make it easier because I would not need a component to flash the diodes, they would flash when a load is run to them.. I need some kind of small button type horn/siren/buzzer for the sound. I need solder, flux, soldering iron, steady hand and a magnifying glass.

I can't think of any other parts, and I am not sure now to shop for the transmitter chip because I am unfamiliar with them and do not understand what certain models are capable of.. etc etc.

Several variables would affect the range as was mentioned earlier.. can you elaborate on what those are?

Nobody has made a simple wireless doorbell or key finder already that I could at least use as a template? Can someone point me in the direction that I should start?
Thanks!

 

[OLIVE2222]

Hi Toddie,

There is a big difference between a wireless door bell and a key finder!
On the door bell there is a push button, mean that the emitter don't draw any current when not used. On the key finder the receiver is always supplied mean that after few days you run out of battery. So as mentioned by jackorocko is indeed a specific project, doesn't mean that nobody
already made it.
You are probably far from a PCB area calculation . The first step is to acquire the electronics and programming skills to implement a HF transceiver on a µcontroller not to build something based on existing schematics.

Olivier

 

[jackorocko]

Not to mention pcb size will ultimately be the size required to fit all the parts. Again you can buy small surface mount parts, but soldering them onto a tiny pcb is not gonna be fun.

It has to be extremely small though, and inexpensive to construct.

I think you will find out that this is an oxymoron. In mass production it may make some sense, but for a one off project, you will be biting the bullet.

 

[Toddie]

I want to mass produce them. I could easily just take a "key finder" and disassemble it and add it to my product however it will be too expensive to sell these products If I have to pay a lot of money for a decent key finder..

I do not see the difference between the wireless doorbell and key finder.

Both the receivers have battery.
Both the transmitters have battery.

There is a push button on the key finder, just like a doorbell.

So look, what do I need to do here... go to school to learn all of this? I thought the internet was a place for free info?

I would take a 50 dollar course to learn how to do this or even pay someone 50 dollars to do it for me.

If the first step is to acquire the electronics and programming skills, then is this forum just for students? Is there any help offered here to acquire these skills or are you telling me that I need to go to school?

I acquire my skills through experience. Is there a free online course I can take? instruction manual? tutorial?

Where i should start is very vague.

I already bought a wireless doorbell. It is on its way in the mail. I figure I can reverse engineer it and I was wondering if I post pictures of the circuitry if users here can identify the parts so I know what to buy, and show me how to connect them on a new pcb. Perhaps I am expecting too much.

I simply need to learn how to make ONE electronic device, I do not need a course in electronics. This is for ONE project, not for a career,
I mean if you are telling me that I have to study and go to school just to make one crappy device that I can buy for 8 dollars then that is ridiculous.

I have searched for a year. an entire year.. for a do it yourself key finder or do it yourself wireless doorbell.. do it yourself RF....
please if you have a link then share it.

If you wanted to build this project what would you do? I have seen no list of parts yet... the only help I have seemed to receive here is that I do not know enough to do it. well OBVIOUSLY! so can I get some help on this project is what I am ultimately asking. ANYONE?

 

[jackorocko]

I want to mass produce them

commercially?

So look, what do I need to do here... go to school to learn all of this? I thought the internet was a place for free info?

That is the case, but if you are looking to produce a commercial product then you need to think like a business and pay for your R&D. There isn't one person out there that is gonna let you take their design and commercially profit from it without some return.

 

[Toddie]

Commercially the pet rock sold millions. It took no research and development. I aim to find existing plans... just like rocks already exist. I just need to slightly modify it just like the rocks were slightly modified with plastic eyeballs and hair. and like I said I would pay for it... but not thousands of dollars. I am thinking like 50-100 dollars. The idea is mine for what I plan to implement this in, I am improving an existing product not developing one from scratch.

There are plans online available for free for Do It Yourself projects.
I have just not found any for my specific application and I would need to modify them.
That is where I was hoping this forum would come into play.
I am willing to do the work and research and develop it myself but I do not know what parts to buy.

Once I know the correct parts, connecting them correctly on the pcb is simply trial and error and I am sure that with something tangible (parts) instead of just an idea that you guys might be able to help more specifically with problems as they arise.

So here is my list of parts I am thinking.. perhaps you can add, remove or correct anything from it.

1) printed circuit board.
2) receiver chip (I could use suggestions on this. I need it to be small but able to be used for long range. I'm not sure if this is a factor or not depending on size it was never specified what the factors were)
3) Flashing Light Emitting Diodes with the integrated circuit built in
4) buzzer (do they make "flashing" buzzers?)
5) a timing chip
6) battery housing
7) capacitor or transformer or something to distribute the power at the proper voltage
8) wire for the antenna
9) solder set

I do not see where software comes into play as this is a relay simple on and off device so I do not know what I would have to program.

I assume the pcb comes with basic instructions on how to connect the components to it.. is there a starter kit for doing something like this? I would buy that and come back when I have learned enough to not ask too basic of questions then.

What do you guys think? At least I somewhat know what I need to do, I am not asking for anyone to do it for me, I just want some help.

 

[davenn]

Hi Toddie

what i am seeing from your last 2 or 3 posts is that you are wanting to do serious and reasonably difficult electronics without any experience at all.
I dont know how old you are, but like the majority of the population under ~ 30 yrs ... they want everything NOW and preferably handed to them on a silver platter. When they have zero or little experience
I see it constantly on the various electronics forums I belong to

welcome to the real world it doesnt happen like that.
I have been in the electronics game for well over 40 yrs. I started playing with electronic stuff when i was ~ 6 or 7 yrs old, bulbs batteries and electro mognets etc, progressing, with time, to single and multi transistor circuits, and then into intergrated circuits.
Its only in the last ~ 10 years that I have got into surface mount component work as seen in that first photo of yours.

The idea is mine for what I plan to implement this in, I am improving an existing product not developing one from scratch.

The kind of help you are looking for, you are NOT going to learn in 5 minutes, 5 weeks or even 5 months. Maybe after 5 years of serious study doing tech college courses and lots of practical experience, the project you are looking at would be something you could handle designing and constructing. BUT definately not for a beginner.

I dont want to sound harsh or overly negative, but you do need to face reality. At your current level of electronics understanding, the design and building of miniature SMD circuits is well out of your league.

To achieve this project with the parameters you have so far set will require a R&D company to do it for you.
You would need to supply to them a very specific list of requirements of the device eg.
power requirements, physical size, transmitter and receiver tolerances and transmit power level ... to name a few
Once they do a design, then you will need a PCB company to make the boards for you, as you are not going to be able to do that yourself. Heck designing SMD PCB's is even out of my league with all my experience!!!!
I dont even make my own standard component PCB's. I commercially build several electronic systems. I supply the artwork to a PCB company, they etch and silkscreen the boards and send them back to me to populate with components
I do the boards at 25 / batch and they cost me $50 for each board ... A LOT of money outlayed .... $1250 / batch


Back to your final Q's I have not seen any kitsets that would do your specific requirements, with what info you have given so far on its intended operation. The transmitter could be as small as a matchbox but the receiver is likely to be much bigger than a cigarette packet

cheers
Dave

 

[Toddie]

Perhaps because the majority of forum users are under 30 you are being biased.
I am over 30.

I do want something now, but it is not results. It is basic help and understanding.
If you look on youtube there are very professional Do It Yourself Printed Circuit boards. Technology has come a long way for the beginner and improvised projects with the help of the internet are booming!

If you look at my first post that picture was taken from a hobby store that caters to beginners as well as experts and they sell starter kits for the receiver... which is much smaller than a pack of cigarettes.

Do I really need to design a new design? re-invent the wheel? I do not think so.
I could replicate something already made. I do not need the schematic, I can create my own.

1) Open a small key finding device.
2) identify and list the parts.
3) copy the PCB and create one
4) Solder

This takes very little research and development as you might imagine.
All one would need to do is customize it very slightly if there was any issue with a patent.

I might add that no matter what help forum I go to for any type of help for any project electronic or not... it seems I get the same type of results. I think if you guys really wanted to help that this would not be outside of your realm.

I am not an electronics expert, but the things I do excel in such as auto mechanics I help all my friends and answer questions in forums.

Anyway, not trying to sound like a spoiled brat but it sounded like, no matter how positive your intentions of not wanting to sound negative, that you were describing me as such.

So here is the deal. I have a wireless doorbell I have purchased coming in the mail. When it gets here I I would like to take pictures of the board and I would like to duplicate it but need to identify what parts are and make a list.

Is that something that you guys can help me with? Perhaps it seems like a grandiose project to you. I just need you to identify the parts... Let me go through my trials and errors and encourage people more. I never gave up on something because the experts told me I could not do it. I have accomplished much. Thanks!

 

[(*steve*)]

OK, how much of this can you figure out how to do on your own, and what few points are you stuck on?

If it's more than that then you have (as davenn points out) a longer road ahead.

Sometimes people ask questions that require a very large investment in time to answer. Often such large investments are not worth the effort because what you are describing is way beyond the present capabilities of the person posing the question.

To build something in electronics is relatively easy if you can follow instructions.

To design something is much harder and requires a much greater depth of understanding.

If someone wants, for example to use a LED from 5V I could tell them to place it in series with a 220 ohm resistor. However, if they want to understand in general terms how to use LEDs, then they would need to understand a lot more.

When it comes to more complex things, like RF design, the knowledge required literally fills books.

Now here you are with a very poorly formed idea, wanting a solution.

Unfortunately, even after reading your initial post a couple of times, I'm at a loss as to what you want it to do.

At this point I generally reword the request in order to illustrate my point. In your case the post is way too long, but I'll tackle part of it:

Once I know the correct parts, connecting them correctly in the workshop is simply trial and error and I am sure that with something tangible (parts) instead of just an idea that you guys might be able to help more specifically with problems as they arise.

So here is my list of parts I am thinking.. perhaps you can add, remove or correct anything from it.

1) workshop.
2) engine block (I could use suggestions on this. I need it to be small but able to be used for long range. I'm not sure if this is a factor or not depending on size it was never specified what the factors were)
3) hazard lights with the flashing relay built in
4) horn (do they make "flashing" horns?)
5) an ignition coil
6) a battery
7) transmission or gearbox or something to distribute the power at the proper torque
8) rubber for the tyres
9) grease set

I do not see where and electrical system comes into play as this is a car simple forward and backward device so I do not know what I would have to power.

Presumably that sounds as useful to you as your post sounds to us.

I'm not saying that you don't have a good idea, but your lack of experience means that it is difficult for you to communicate it to us. Added to that is your inability to see what things are easy or hard -- and that too comes from a lack of experience.

What you need to do is to explain clearly and concisely what you want to achieve, not how. Start from a simple "when this happens I want that to happen" approach.

 

[Toddie]

Ok. Very simply...

I want to disassemble a small, cheap, relatively simple electronic device, identify the components that are used in its construction, buy those components, create a pcb using the original pcb as a template, and recreate this same device (reverse egineering).

Would that be something anyone can help with?

p.s. i am not stuck on anything yet, the device has not arrived, however I will need assistance identifying the components so that I can make a shopping list. Just wondering if that is something that anyone is willing to help me with!

 

[(*steve*)]

OK, whenever you get the device,

1) tell us what it is
2) disassemble it
3) take photos of the PCB

And we'll see what we can tell you about it.