# A simple project - don't know where to start

#### dew

Joined Dec 4, 2008
2
First off I'll say I have one class of basic electronics, but am pursuing the full degree. I do have some previous soldering experience as well. I think this is a simple project, but I'm not entirely sure.

I am trying to put together something that I think and hope is fairly simple that is desperately needed. This will be something that is placed on one location where somebody will push buttons, that will alert us in another location which buttons were pushed (and hopefully allow us to reset those buttons once we do what was required). Hopefully this is wireless, as it will have to run about 200 + feet if not.

In location one I need about 10 or so buttons that these people can push. This will light up the corresponding led at location two. Once we perform these actions hopefully we can push the corresponding button at our location so as to turn off this light.

I'm not sure where to start. I've only ever done some actual functioning circuits with a purpose a couple years ago, so I really don't know what I'm trying to do.

If anybody can give me some tips as to what to start looking at that would be awesome. I'm not asking for somebody to design this for me, just for some tips on what to read into.

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#### leftyretro

Joined Nov 25, 2008
395
Well it's certainly an achiveable project. Small microcontroller boards at each end could handle all the switch and indicator input and output requirements while communicating between themselves using low cost RF wireless link modules. Maybe under $200 in material, depending on your switch and light requirments. Your effort would be in the designing and building of the physical input and output stuff, switches and displays and in writing and downloading your custom software program into the micro controller boards. All the PC software you would need to develop your programming is free with these microcontrollers. Here are but just one example of modules that could work: One microcontroller development board example: http://www.seeedstudio.com/depot/seeeduino-v11-fully-assembled-arduino-compatible-p-114.html?zenid=9f6118c193cee9f8b7337d4df91a2eca One Wireless RF link modules: This is a tranciever module meaning it can both send and receive data, as you stated that might be a requirement. If data only has to go in one direction then there are even cheaper simpler modules avalible http://www.sparkfun.com/commerce/product_info.php?products_id=705 Again these are just examples. Now a days there are tons of cost effective modules and parts for small projects. It's a great time to be in the DIY electronics hobby. Lefty #### kahafeez Joined Dec 2, 2008 150 yah dude u'll have to use a microcontroller to scan buttons at the transmitting end ..... use an RF module to send the data and at the receiver an RF receiver and a micro controller to understand the signal..... i think u could also use an FM transmitter instead of a RF module bt the FM should work on a freq other than 88 - 108 MHz cz the interference might come ..... what do u say people ..... am i right abt FM ??? #### RiJoRI Joined Aug 15, 2007 536 While you may wind up using a micro, you do not HAVE to use one: consider that Bell Telephone brought out the DTMF telephones in the 1960's, if I recollect. 12 buttons generating different tone pairs, with tone decoders on the other end. I'd advise you to split the project into two or three parts: collecting the button information, displaying the button information, and transmitting the button information. Use a very simple transmission scheme (2-wire serial, perhaps) to get the collection/display operating, then (or if you are working with a group, simultaneously) develop the transmission scheme. --Rich #### SgtWookie Joined Jul 17, 2007 22,210 You need to know what frequencies that you can legally transmit on in your country. Some countries prohibit ANY transmission by civilians. Some allow limited power transmissions on narrow bands of frequencies. I'm not going to try to research this for you, particularly since I have NO clue where on the planet you live. This is YOUR responsibility. If you mess up and transmit on a frequency that you are not legally allowed to, the authorities will grab you, confiscate all of your equipment, throw you in jail, and fine you$10,000 (USD).

This is in the USA. If you live elsewhere, the authorities may be much less pleasant.

I'm not kidding.

#### kahafeez

Joined Dec 2, 2008
150
yup the DTMF thing is also a good idea..... i believe there are ic which will help u detect which button was pressed .... at the transmitter end i think they are called encoders if i'm nt wrong

#### IT_Guru

Joined Nov 20, 2008
17
Use a PC Parallel port, and you can detect and respond appropriately to ~128 different buttons (or 65534 with some MUX chips) but... unless you also wire in a wireless encoder/decoder, thats alot of 2 wire pair all over the building. You might also consider using X10 (thru the AC powerline) devices. they can easily support that many 'customers' and no wires either - each 'customer' must have 110 ac outlet in their area tho. Check it out

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#### dew

Joined Dec 4, 2008
2
Hi guys thanks for all the tips.

I'll look into what you guys have suggested. I will be looking into the frequencies we can use (USA). I also need to make sure I don't choose a frequency that is going to interfere with the wireless microphones we use.

I think using the microprocessors might be the "easiest for us" as far as what we're looking to do. Really not looking to run wire either.

Definitely not using X10. We're actually only looking to communicate from one area what we need done, not actually control the lights from that area. The building has X10 now and it's a nightmare.

Thanks again everyone for your tips. I'll look more into this next week when I have the time and try to plan out what I think we need. I do have multisim as well for designing the thing, so hopefully that cuts out a lot of my testing and hoping.

#### IT_Guru

Joined Nov 20, 2008
17
X10 is notorious for not working well IF there is a transformer-run device located anywhere in the premises. These tend to absorb the superimposed x10 signals.

Nowadays, where we all have instant on functionality on TV and PC, and LED clocks in all our appliances (power Vampires) people are having problems getting reliable use of X10. I certainly would not use it for any security function ;-)

#### KL7AJ

Joined Nov 4, 2008
2,224
First off I'll say I have one class of basic electronics, but am pursuing the full degree. I do have some previous soldering experience as well. I think this is a simple project, but I'm not entirely sure.

I am trying to put together something that I think and hope is fairly simple that is desperately needed. This will be something that is placed on one location where somebody will push buttons, that will alert us in another location which buttons were pushed (and hopefully allow us to reset those buttons once we do what was required). Hopefully this is wireless, as it will have to run about 200 + feet if not.

In location one I need about 10 or so buttons that these people can push. This will light up the corresponding led at location two. Once we perform these actions hopefully we can push the corresponding button at our location so as to turn off this light.

I'm not sure where to start. I've only ever done some actual functioning circuits with a purpose a couple years ago, so I really don't know what I'm trying to do.

If anybody can give me some tips as to what to start looking at that would be awesome. I'm not asking for somebody to design this for me, just for some tips on what to read into.