TV-B-Gone flashlight
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TV-B-Gone flashlight

by gee on Mon Mar 11, 2013 7:24 pm

I'm not the first person to do this, but here's my latest TV-B-Gone variation.

http://www.youtube.com/watch?v=858UZ-zDsZU

(I'm using a camera with the IR filter removed, which is why you can see the IR lighting up the room.)

Parts list:

5 chinawatt IR LED: http://dx.com/p/5w-940nm-infrared-ir-le ... ver-152456
P60 heatsink/reflector: http://dx.com/p/26-5mm-aluminum-reflect ... itter-5955
Nanjg 105C LED driver: http://dx.com/p/17mm-2800ma-5-mode-regu ... -5v-127684
Flashlight body which takes a P60 pill: http://dx.com/p/ultrafire-wf-502b-alumi ... ack-102370

Other required bits are a lithium battery, charger, Arctic Alumina thermal epoxy, solder, wire, an ATTiny85V microcontroller in a SOIC package, and a 2.5mm/4MHz ceramic resonator with built in caps.

The LED driver has eight AMC7135 350mA constant current LED drivers for a total of 2.8A LED output current, and they can switch fast enough for consumer IR. It uses an ATTiny13 microcontroller for PWM brightness control, and it conveniently as the same pinout as an ATTiny85. The Tiny85 isn't available in a narrow SOIC, but you can J-lead the legs and make it fit, which I did:

Image

The back of the driver has three mode-setting stars, which you'd ordinarily solder to ground to change the driver's behavior. The two rightmost stars go straight to the oscillator pins of the Tiny13/85, and the 2.5mm x 1.2mm resonator fits pretty much perfectly. I'm using the second star for region selection, ground it for EU codes or leave it floating for north american codes.

Image

The Nanjg 105C driver couldn't be better for this mod, everything just perfectly works out.

Next, the IR LED gets mounted to the P60 pill. This is actually a picture of my first failed attempt, where I soldered the IR LED directly to the reflector without checking if the LED's heatsink base was isolated - it wasn't, and result was a blown LED. Whoops. I built another pill using Arctic Alumina to hold the LED in place, maintaining somewhat reasonable thermal conductivity while keeping the LED base isolated.

Image

I don't have any pictures of the rest of the process, but a couple of wires get soldered to the driver and it's soldered into the backside of the heatsink that the LED is on. The reflector screws onto the pill and rests on the top of the LED, and the assembly then drops into the flashlight body. There's a few guides around the net explaining how to build a DIY P60 flashlight.

The flashlight is unbelievably powerful - you can turn off TVs from the complete opposite corner of a department store, or aim it at an apartment with a TV flickering inside and watch the flickering disappear. Having almost 3 amps of LED drive current and half decent optics makes for great range.

I'm working on a successor to this flashlight now, keeping the same driver but using an osram "black oslon" 940nm LED. The oslon uses two IR dies in series, and should put out at least twice as much IR power as the DX LED with the same drive current. I've got a PCB designed to mount the Oslon on, but haven't got around to ordering it yet.

The code running on the flashlight is roughly based on the TV-B-Gone code, modified for operation at 4MHz and with high temperature/low battery shutdown added. I'll release it eventually.
gee
 
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Joined: Fri May 22, 2009 9:21 am