LED to Power Ratio Question

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RealRitzcracker
 
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LED to Power Ratio Question

Post by RealRitzcracker »

If ladyada's kit uses 4 LEDs to 2 AA battery's.

Could I modify the kit to use 8 LEDs like the SHP but only use 4AA Battery's?

Just wondering cause I'm trying to make the most powerful TV B Gone I can that can fit inside a cell phone.

I know that I can fit 8 LEDs I'm not sure on how much power I can fit though.

magician13134
 
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Post by magician13134 »

Using four AA batteries will allow you to hook up the LEDs like this:
Image


But it won't be as powerful as the EHP/SHP version as those use an extra transistor to boost power even more


(Anyone correct me if I'm wrong on either of those claims)

RealRitzcracker
 
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Post by RealRitzcracker »

What if I add an extra transistor?

RealRitzcracker
 
Posts: 140
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Post by RealRitzcracker »

How much power do I need to get the full effect of those 8 LEDs?

12Volts?

rockcrusher
 
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Post by rockcrusher »

hi all===I would also like to double the emitters as shown above. can anyone tell me if I need to change the resistors for this to work. I'm planning on using a 9 volt battery. any input would be appreciated.===== :) thanx Rob

magician13134
 
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Post by magician13134 »

I don't think a 9V is the best choice. If you'll notice, the SHP TV-B-Gone uses that, but it needs extra coin cells due to the high internal resistance from a 9V.

@RealRitz, remember, on Ladyada's kit, all of the voltage going to LEDs also goes through the Attiny85. It can only take up to 5V, that's why the two diodes were added to the EHP version, to keep that voltage to the microchip lower.


(I'm not used to being the one answering questions, I usually ask them, correct me if I'm wrong on this :) )

I_am_bad_at_this
 
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Post by I_am_bad_at_this »

well, i succesfully added four ir leds onto my tv b gone. It now uses 4 AA.
i made a little circut with four resistors, transistros, and ir leds. the resistors went from the transistors to one central point, with was soldered on the original tv b gone resistor (on the side near the ATTINY 85). the extra leds use their own two AA, and a ground wire had to connect the new boards ground with the original boards ground for it two work.
Image
Image

i used this schematic a quickly made for the add on board
Image

RealRitzcracker
 
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Post by RealRitzcracker »

What about 2 Coin Cells and 4 AA?

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