new to robotics and would like some help with transmitter, receivers and servos?

[sampenso08]

hi I am new to all this robotic stuff and i would like some help please. i am a student in year 12 studying systems engineering and i am planning on producing a mail box that tells the home owner when they have received any mail. i plan on doing this by using a motion sensor to detect movement in the letter box. the motion sensor will act as a switch to activate a transmitter which sends a signal to a receiver inside the home. this receiver will then activate a servo witch moves an arm that flick a switch witch activates a small LED to notify the user of mail. the servo arm will then move back to the off position leaving the LED on.

i am not sure as to the types of transmitters, receivers, and servos that i need? I'm am also not sure as to how to turn on the transmitter to send the signal to the receiver? also i would like to learn how to hook up the receiver to activate the servo?   

Any help and info would be greatly appreciated!!

[superchiku]

ur application is actually quite simple ,1st of the transmitter , motion detector all can be done with the help of a microcontroller. just use ir to see if any motion has been detected , program ur  microcontroller to switch on the led when motion has been detected , just reset it when u takt ur letters out and everything will start all over again

see simple..

[sampenso08]

  :)thanks "superchiku" that helps me alot. 
could you maybe give me a list of some of the main components that i need to buy because i dont have any on hand and i am not sure what to ask for when i go to a hobby shop to buy the required components.

thanks again!!

[szhang]

Microcontroller: PIC (http://www.microchip.com) or AVR (http://www.atmel.com/)
You can get these at any major electronics distributor (Digikey for example)

SparkFun (http://www.sparkfun.com/) has a lot of RF modules.

Though you'll definitely need to learn a bit about programming microcontroller (usart/serial comm. for alot of the RF modules) to use them.

You probably need random resistors (just get a whole pack of different ones).  You can get these anywhere.  Same with LEDs.

Although, I would recommend you plan out what you want to do first before you go crazy shopping.

[Private Reid]

well, I was thinking of having a LDR in the letterbox then with just some simple circuitry the LED in the house would go on when light enters the letterbox (ie. opening the door). I know how to do it... Back when I was a kid i used a LDR to to check if anyone (eg. my sistor) had opened my money tin...I'll have to search around for the schematics...    Although it's very simple



No need for a microcontroller

[szhang]

No need for a microcontroller

except if you want (relatively) easy to setup wireless...

[sampenso08]

all for you guys have given me some great ideas as well as some cool alternatives. i like the idea with the LDR. i built a kit last year that used one, it was meant to work like a cricket. when ever it was exposed to light it made a chirping sound. 
on the track of using an LDR, would there be a way to hook it up the a transmitter so that the mailbox would be wireless and the signal would be sent onto the home turning on the LED?

some wiring maps would be greatly appreciated because I'm not so fluent in all this technical mumbo jumbo.

thanks again to everyone that is helping me out

[Private Reid]

ok, well I found the book that has the ldr curcut in it


http://images.google.com.au/imgres?imgurl=http://www.dse.co.nz/isroot/dse/images/products/B2600~SML.JPG&imgrefurl=http://search.dse.co.nz/electronics/electronics&h=80&w=61&sz=3&hl=en&start=1&tbnid=6eGFDxnrJJdQkM:&tbnh=74&tbnw=56&prev=/images%3Fq%3Dfunway%2Bto%2Belectronics%26gbv%3D2%26hl%3Den


I know i have that book around my house somewhere...  The book is volume 1


To make it wireless...

Thats abit hard, what I would suggest is to thread the wire (from the curcut to led) through a tube underground. It would be easy enough to dig a 10cm hole in the direction of your house...unless you have a concrete walkway or something...

[sampenso08]

"Private Reid" your idea is good but i would really like to make it wireless because it is something i have never done before and i would like to learn about this method. i am also interested in learning how to work with transmitters and receivers and would like to intergrate my interest into my project. i know it will be challenging for me and that is what i like about my project. I'm up to the challenge and if you have any ideas or know someone that has a vast knowledge of this kind of stuff i would like to hear from them.

you have helped me out alot, keep the ideas flowing!!

[Private Reid]

kk

well i found the book, i got pic here

www.no1name.zoomshare.com

I have set it out very clearly

I will still have to think about the whole wireless idea...

[sampenso08]

thanks again! this will help out alot!
and thank you for looking into the wireless idea of mine, i appreciate your time and effort.
 

[Private Reid]

No problems 

It's nice to think a noob like me can help someone else! 

[superchiku]

well using a simple circuit will give u simpler solutions but what if u want to add an extra functionality such as 10 leds are connected and u want to switch on one by one , the no of times a letter is dropped to a max of ten wallah u need the microcontroller then...

[Private Reid]

well using a simple circuit will give u simpler solutions but what if u want to add an extra functionality such as 10 leds are connected and u want to switch on one by one , the no of times a letter is dropped to a max of ten wallah u need the microcontroller then...

True...in most cases.

But You could still do the 10 LED thing without a microcontroller, just use buttons in the mail box. Another eg would be    If you wanted a robotic arm to slap the postman when his delivers a bill. Now that would need a microcontroller! Because somehow the arm needs to see how big the postman is so it doesn't slap his neck or something so you would need a range of sensors and a microcontroller to do that...

[superchiku]

slap the postman or open the door of the dog house 

[Private Reid]

slap the postman or open the door of the dog house 

lol

Poor posty 

[sampenso08]

that whole 10 LED thing is probably alittle to complex for me right now. i want to use a transmitter, receiver and maybe a servo to turn on the LED. if you think replacing the servo with a microcontroller is better, then it would be a big help if you could send me some wiring maps or some pictures with info.

thanks, and that slapping the post man thing made me laugh

[Private Reid]

i don't believe a microcontroller would be good for this project cause a microcontroller requires alot of programing and wiring. It would be cheaper to buy the bits and pieces from the picture i supplied (from the link above) and hook it all up. as 4 the wireless i think i have found a solution but ill test it first before sending false infomation over the internet... I reckon you could compete this projet with a $20 note 

[Private Reid]

servo to turn on the LED

servo? the LDR (Light dependent resistor) will turn the LED on

[superchiku]

he is talking abt a switching mechanism , like the servo flips the switch on and the led turns on

yes microcontroller would be a little complex for u but certainly the wiring will be much decreased if u use mcu but i recommend since this is ur 1st time, go for simpler circuits without mcu

[sampenso08]

thanks. i will use a LDR to detect the light when the mailbox door opens. what i dont know how to do is make the process of the LED turning on inside the house wireless once the LDR detects light. I'll wait and see what "Private Reid " sends?

[Private Reid]

right, i have tested my theory and it "should" work

Although i don't have time to post right now so i shall just give the basics

 Note: The project will cost Average $40 (all up) And it is more of a hack than a project. And i don't know if you will learn much from it. But you might, just I didn't.

The idea is that using a remote from a rc car (and the rc car itself) to send the signal "WIRELESSLY" to the house.

Note: You will have to buy a rc car of ebay, or use an old one

Now, I have done the project myself...(well sorta half in my head and the other half on paper and in my shed) But in the end it will look very professional and it's cheap.

Hope that keeps you going until next time.

[Admin]

For the transmitter . . . if you don't want to bother with a microcontroller:

LDR connected to a comparator (detects on/off)
comparator sends output to a transistor input
transistor turns on a 555 timer
555 timer output sent to transmit line on your transmitter


the receiver then looks for a square wave

[sampenso08]

"Admin" your idea is very good and it is the closest to what i am looking for in doing with my project. i dont know if you read my previous posts but I'm not to flash with my technical lingo, if you know what i mean. 
 if you could, could you please send me a list of components that i would need to buy from a hobby store. this would help me out alot!

thanks for your help, it is much appreciated!

[Admin]

Well a list would be rather useless to you without a schematic!

Do some research on each of those terms in my last post you didn't understand. Then post what you think the schematic will look like, and we will help you from there.