0

Making Open-Source TV-B-Gone?
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

by morcheeba on Sun Jan 13, 2008 3:10 am

Just reverse-bias the LED to use it as a detector, and then calibrate with the 59.94Hz video frame rate of the TV. As a bonus, if you check during the pause between codes, you'll know immediately if the device has been successful. Quit sending codes at that time & you'll save battery life.

Ok, not too practical :)
User avatar
morcheeba
 
Posts: 10
Joined: Sun Jan 13, 2008 2:53 am
Location: Colorado

by magician13134 on Wed Jan 16, 2008 10:06 pm

Ok, another question... what are the capacitors and resistors for? I'm working with one on breadboard that works fine without them... Do they just increase the range or are they a safety feature so as not to kill the LEDs? Thanks
magician13134
 
Posts: 1119
Joined: Wed Jun 13, 2007 9:17 am
Location: Ann Arbor

by adafruit on Wed Jan 16, 2008 11:39 pm

they are to stabilize the power supply, you can google for 'power supply decoupling capacitors'

adafruit
 
Posts: 12151
Joined: Thu Apr 06, 2006 4:21 pm
Location: nyc

by magician13134 on Thu Jan 17, 2008 8:24 pm

Ok... I've run into a snafu here, and I'm getting a little worried now. I need this finished in about two more weekends so I'm kind of nervous... Anyway, I've got 6 transistors hooked up , I'm using a 9V battery that I've regulated to 5V for all power. Everything is hooked up, the transistors are all getting power to the center pin (That's the one that takes a little current... I'm not sure if it's B, C, or E...) and it's on breadboard, but I only have two IR LEDs. So everything's hooked up, it's just that only two LEDs are actually attached. This works fine, I get about a 40' range, but as soon as I add another LED, it stops working. The other LED I added is a visible white LED. So if I have one white and one IR, it works (~30' range), two IR, it works (~40' range), two IR and one white, they all flash, but the TV is unresponsive at any range.

I desperately need more than two LEDs in this circuit though because right now, I've got about a 10 degree margin of error... Can someone please help? Is it because I don't have the decoupling capacitors? Do I need to use more output pins? If so, can I just use two tiny85s? Thank you very much!
magician13134
 
Posts: 1119
Joined: Wed Jun 13, 2007 9:17 am
Location: Ann Arbor

by magician13134 on Thu Jan 17, 2008 8:35 pm

These pictures make it look more complicated than it is, trust me, it's simple



Image

Image
magician13134
 
Posts: 1119
Joined: Wed Jun 13, 2007 9:17 am
Location: Ann Arbor

by oPossum on Thu Jan 17, 2008 8:55 pm

There really should be a resistor on the base of each transistor and decoupling caps on the AVR and 7805.

I think the biggest problem right now is that the 9V battery drops below the 6.5V needed by the 7805 when 3 LEDs are used. The quick fix for that is to power the LEDs with one battery and the AVR with another.
oPossum
 
Posts: 636
Joined: Fri Oct 26, 2007 12:42 am
Location: Michigan, USA

by magician13134 on Thu Jan 17, 2008 9:00 pm

Unfortunately, I don't have enough space in the project enclosure for two sets of batteries... But you are right, when I use three volts it works fine. Would resistors (what value) at the base/decoupling capacitor(s) (what value and where) fix this problem? Thanks very much for the insightful response
magician13134
 
Posts: 1119
Joined: Wed Jun 13, 2007 9:17 am
Location: Ann Arbor

by oPossum on Thu Jan 17, 2008 11:21 pm

Yes, resistors could be used to limit the LED current so the battery voltage does not drop to low. The current from a 9V battery is limited, so you will never be able to drive the LEDs very hard without significant voltage drop. I think the best battery for maximum LED current would be 3 AA. If you want to stick with a 9V, give this circuit a try.... It will work without the resistors, but not nearly as well as with them. The battery voltage drop will be limited to about 7 volts because each LED has a forward voltage drop of about 2 volts and the transistor about 1 volt at 250 mA.

Image
oPossum
 
Posts: 636
Joined: Fri Oct 26, 2007 12:42 am
Location: Michigan, USA

by magician13134 on Fri Jan 18, 2008 12:50 am

Great success! 8) The LEDs were MUCH brighter when I just used tow in series, maybe because they were white, not IR, my IRs should come in the mail tomorrow, so I'll test it again then, and another question, can I hook up more rows of LEDs in series with more transistors, or would that cause too much drag on the battery?

Again, thanks!
magician13134
 
Posts: 1119
Joined: Wed Jun 13, 2007 9:17 am
Location: Ann Arbor

by magician13134 on Sat Jan 19, 2008 10:54 pm

Hmm, I decided to try to use two output pins of the tiny85, so I could get more power, and caitsith2 helped me get that code. Both pins 5 and 6 continuously drive the IR LEDs as long as there is power, but pin 5 seems to be putting out slightly less current than pin 6, so when I hook it up to a transistor, it just flashes at a regular interval... what's going on here? Shouldn't pins 5 and 6 output the same amount of power?
magician13134
 
Posts: 1119
Joined: Wed Jun 13, 2007 9:17 am
Location: Ann Arbor

by Entropy on Sun Jan 20, 2008 12:27 am

Could be manufacturing variance, or a known aspect of the chip's design. Check the datasheet for the Tiny85?
Entropy
 
Posts: 472
Joined: Tue Jan 08, 2008 12:43 am
Location: Owego, NY USA

by magician13134 on Sun Jan 20, 2008 3:11 am

You know, I really should start listening to advice given to me (especially when given by several people), it was due to a lack of a resistor... I'm not sure why... maybe the voltage dipped below the brown out level of the microchip (?) that caused it to continuously reset...?

I dunno. The point is, it works, you guys were right, sorry
XP
magician13134
 
Posts: 1119
Joined: Wed Jun 13, 2007 9:17 am
Location: Ann Arbor

by magician13134 on Wed Jan 23, 2008 10:03 pm

Would anyone be able to etch a circuit board for me for this project? I'm very bad at it, especially drilling the holes... If I upload a bmp file would anyone be willing do that for me? Thanks
magician13134
 
Posts: 1119
Joined: Wed Jun 13, 2007 9:17 am
Location: Ann Arbor

Etching PCB.

by stevemurphy on Thu Jan 24, 2008 8:48 pm

Yeah, drilling holes in PCB's is a pain isn't it? For a one-off like you're doing you might consider a pre-drilled board like this one at Radio Shack:

http://www.radioshack.com/product/index ... Id=2102845

Image

(You can get larger and smaller ones, depending on what you need). You just place all of your components into it and make your connections point-to-point using wire. The top is just white paint, on the underside are copper pads with predrilled holes that match the mask on top. Oh, and the best part is it only costs two bucks.

stevemurphy
 
Posts: 3
Joined: Thu Jan 24, 2008 8:36 pm
Location: Boise, ID

by Kova on Tue Jan 29, 2008 7:52 am

oPossum wrote:Try this firmware - it has 31 codes compressed to fit in the 2K memory of the 2313.

Download


Hi oPossum.
Is it possible to have the source for compressing 31 codes in the memory of the 2313?
I want to use the Europe code :roll:

Thanks a lot!
Sorry for my english ;)
Bye ;)

P.S. I have downloaded the tvbgone_eu.c file, what is the correct command to compile and program it ? Thanks
Kova
 
Posts: 3
Joined: Tue Jan 29, 2008 7:47 am

Please be positive and constructive with your questions and comments.