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Building "tricorder", need advice...

:: EPE Chat Zone ­:: ­Radio Bygones Message Board :: » EPE Forum Archives 2005-2006 » Archive through 28 June, 2006 » Building "tricorder", need advice « Previous Next »

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Escher
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Username: Escher

Post Number: 1
Registered: 06-2006

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Posted on Monday, 26 June, 2006 - 09:34 am:   Edit Post Delete Post Print Post

Hi,
I'm about to start work on a project and I need some advice. As the title suggests, the idea is to make something along the lines of a tricorder, more like an electronic multi-tool really, it may have some practical value but it's mostly just a fun project. I already have the project box, a 1xAAA mp3 player, keyring pda, fm radio, laser pointer, and a few basic components, to which I'm planning on adding a set of high-brightness LEDs (IR, red, white, UV), an RF detector, and depending on space a gas detector and/or metal/voltage detector. Most of them will be wired in such a way that they can be patched into each other (eg. ir sensor > mp3 > ir led = crude tv remote with macro function). There are however, a few things I'm not sure about, and I'm hoping some kind person here could explain.

The power source for the unit is possibly the biggest problem, I don't want to have to install a seperate battery for each component, but I'm guessing there will be problems if I try to run mutiple systems from the same battery? I have a cople of 7.2v infolithium camcorder batteries, and it seems like 1 of these would be the most compact power source I could use. Would I just have to use a set of resistors to get the right voltages, or is it more complicated?

Soldering is another biggie. I'm ok at soldering on stripboard, but in order to wire the mp3 board to the rest of the unit (and the controlls I'll be mounting to the facia), it'll take some very precise work. I took it to the soldering guy at the local electronics shop but he doesn't want to risk it. I've seen articles on electronics sites where people have replaced the memory chips from these things though and that's way more difficult than soldering wires to the buttons, so it must be possible. Will I need to find a professional to do this?

The next thing is something I can probably find for myself with enough research but since I'm posting here anyway I guess I may as well ask. I was going to wire the alarm from the PDA to start up the mp3 player, but there needs to be something between them that will convert the alarm signal (musc or series of beeps) into a pair of button pushes, about 7 seconds apart. I would guess that I'd need to use a latch then a 555 timer and counter, then a relay to short out the contacts on the mp3 player, am I on the right lines here? anyone know of a schematic for this floating around that I haven't found?

This isn't that important but is there any way to modify / build an RF detector so that a signal on the 2.4ghz frequency is detected seperately to other frequencies? so I can scan for any RF or narrow it down to just Wifi and bluetooth.

Any other advice would be greatfully received.
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Tvmender
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Username: Tvmender

Post Number: 57
Registered: 05-2005


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Posted on Tuesday, 27 June, 2006 - 09:31 pm:   Edit Post Delete Post Print Post

Hi Escher,

Sounds like a very complex idea you have in mind!

It sounds like its more suited to a microcontroller rather than simple electronics such as timers and such (you could use them but I am sure this thing wouldent be hand held, maybe castor mounted?!)

Another problem you might have is powering all your devices from one source. You will probably have to buid a regulator system comprising of several regulators each supplying a different voltage to each of the devices as they require it.

How do you want all the devices to interact? Do they all need to talk to some central point and have a read out of some sort? If so, I would definetly look into PICs (there are many good articles in epe on these) as you could interface your bits and pieces with the PIC and have it deal with all the interconnection of devices and display the results on an LCD or LED display?

Adding hardware to your design would be fairly simple if you used a microcontroller, you could make some minor hardware changes and some software changes and hey presto!

The RF scanner you suggest sounds like a radio scanner available (sometimes cheap) from an electronics shop, maybe it would be easier to pull one of these apart?

Good luck,

- Tvmender
"Nothing unreal exists"
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Escher
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Username: Escher

Post Number: 2
Registered: 06-2006

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Posted on Tuesday, 27 June, 2006 - 10:30 pm:   Edit Post Delete Post Print Post

Thanks for the advice, it does seem like a microcontroller based controll board would be a perfect solution to this, I tried learning how to use them some time ago but I just couldn't get a foothold. I even tried building a circuit using a freeware schematic and .hex file but it just sat there and did nothing. I can code in a few languages but for some reason I was never able to figure this out. Maybe I'll give it another go, it would solve a lot of the connection and space problems I've encountered.

The idea that I had when I started getting the parts for this was to just take a project box, mount as many gadgets as I could into it, cut holes in the facia for the ones with displays, then take every button, socket, and led on the boards and move them to the exterior of the box, with a single battery pack running the whole thing. Then I came up with the idea of plugging the mp3 player into the radio, or IR port, at first I was just going to have a small bank of audio sockets at the back of the unit, and use a short audio cable to handle the connections. Then as the design became more complex that idea became impractical, I'd left that part of the design blank, but thinking about it, it seems like some kind of controll board might be the best solution.

oh and the RF scanner I was going to add was one of those keyring sized bug/wifi detectors.

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