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Tiny TV-B-Gone
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Please be positive and constructive with your questions and comments.

Tiny TV-B-Gone

by war6763 on Mon Dec 10, 2007 4:29 pm

Hey all, I know, first post, etc. :D

Anyway, I got bored in class a couple days ago and decided to make this tiny version of the open source TV-B-Gone... It measures about 1.75 x 2 inches... so it's pretty damn (excuse my french) small. It's based on the v1.1 schematics so all you should have to do is load up the firmware and go! It uses tiny surface mount components and a surface mount microcontroller. The only things through hole are the LEDs, the button (I was too lazy to make a surface mount footprint for the button) and the power connector.

Everything is the same as in the other schematic, values, etc. everything should work just fine :) I tried keeping everything on the top layer so some funky routing was in order, but that is easily cleaned up with a single VIA. Let me know if that's better for you all and i'll throw that in, or feel free to do so yourself!

Instead of having a programming header I went ahead and just left solder pads. This way, they don't take up that much space and are cheaper tha buying a connector that you'll only use once.

Enjoy!!

Image

Remember, this thing is TINY!

*edit*
I should probably paste in a download link, no?
http://www.badongo.com/file/5540798
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by caitsith2 on Tue Dec 11, 2007 4:18 am

For neater routing, swap R1,R2,Q1,Q2,LD1,LD2 pair, with R3,R4,Q3,Q4,LD3,LD4 pair.

Here is the new schematic/board files that does this. (And in the process, I made the schematic freeware edition friendly for modification. (A few components sat just outside the invisible border. (The white border does NOT count.)))

http://www.caitsith2.net/projects/tvbgone/tiny_tv_b_gone.zip

Image

And if you are going to have this board made, and order parts from digikey (and mouser for LEDs/Battery holders), plan on ordering at least enough parts and PCBs to make at least 5 of them. (The minimum quantity of most of the components needed at digikey, is 10.)

If you are going to use the 120 ohm resistors for the IR signals, then program the chip BEFORE you mount the IR LEDs + Transistors + Resistors. (I know this, because it took me about a week to find out why the programmer wasn't working right with my TV-B-Gone kit.)
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by war6763 on Tue Dec 11, 2007 8:45 am

Hey! Thanks for the update!! Once I get around to having the board sent off i'll post more info about it!! I might just go and mill the board, but I think it might be a pain to do correctly...

Anyway, thanks a lot!
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by caitsith2 on Tue Dec 11, 2007 12:39 pm

I just realized another thing to do. Rotate the switch on the board, so that the connections run horizontally, not vertically. This allows the AVR connections to take less bends to get to the IR driver resistors.

(I replaced both the preview image and the main zip file, the download link remains the same.)
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by caladan on Mon Dec 17, 2007 3:25 pm

Hmm, I wouldn't call that board small. I've made few days ago something like this. :-)

http://img407.imageshack.us/img407/8972 ... danbn8.png
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by adafruit on Mon Dec 17, 2007 3:42 pm

so small...but the batteries are whats really big. although maybe a CR123A would be a good match.

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by caladan on Mon Dec 17, 2007 6:13 pm

I'm gonna use CR2032 when I finally buy that damn ATTiny85 - it's hard to get those in Poland... :/
It's a pity I have not waited few days for v.1.1, so board is done for v. 1.0. Got four of those straight from my PCB factory :D
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by Hazard on Mon Dec 17, 2007 6:52 pm

I want one! If I have the time I may etch my own :P
Image
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by adafruit on Mon Dec 17, 2007 8:03 pm

caladan wrote:I'm gonna use CR2032 when I finally buy that damn ATTiny85 - it's hard to get those in Poland... :/
It's a pity I have not waited few days for v.1.1, so board is done for v. 1.0. Got four of those straight from my PCB factory :D


cr2032's wont be able to supply the current you need. you need a large battery

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by maltman23 on Tue Dec 18, 2007 1:49 am

cr2032's wont be able to supply the current you need. you need a large battery


The commercial TV-B-Gone keychains use one CR2032 battery to drive the one IR emitter it comes with. Using a CR2032 will work for the TV-B-Gone Kit, too, but the range will be greatly reduced compared to using AA batteries. The CR2032 will also get low pretty quickly, since we're pumping lots of current through 4 IR emitters with that little coin cell.

Coin cells have a relatively large internal-resistance, which means that the voltage will sag quite a bit while the microcontroller is trying to pulse the four IR emitters. If the voltage sags momentarily below 1.8v (if you are using the ATtiny85V part), then the BOD (Brown Out Detector) will trigger a reset.

Mitch.

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by caladan on Tue Dec 18, 2007 5:18 am

I've got still some experiments to do, so probably this one will be a short range version, and another will be long range, probably powered from 3xAAA batteries, or even 6F22 (9V) :-)
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by maltman23 on Tue Dec 18, 2007 6:45 am

Cool. 8) For your short-range version, you may want to experiment using larger resistors for R1, R2, R3, R4. There will be a trade-off between range and battery-life.

With a good 9v battery you can really get some current flowing through the emitters! You'll have fun with that. :) Just be sure to use a separate 3v battery supply for the microcontroller, since it's max voltage is 5v (though people have said they've been able to go as high as 6v without frying it).

Mitch.

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by nonstopred on Tue Dec 18, 2007 10:33 pm

i just measured my board that i got and its 1.25x1.75 inches. Yours is bigger than the original one....
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by war6763 on Wed Dec 19, 2007 2:10 pm

Doh! Alright, i'll work on something smaller... :D
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Please be positive and constructive with your questions and comments.