5 Volt Problem (1.2 Kit)

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1965mustang
 
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5 Volt Problem (1.2 Kit)

Post by 1965mustang »

Hello all,
we have the 1.2 TV-B-Gone Kit and it runs great with 2 AA Zell's.
If we make an Input of 4,9 - 5 Volts (for more range) one of the Narrow beam IR LED LED2 is not sending any more and all the four NPN Transistor where very hot for a Moment.
Now with 3 Volt all is fine but the LED2 or/ and the Transistor 2 is broken
In the Manual stays that a voltage of 5,5 is Maximum?!

Thank you very much for every help and Suggestions
Johnny

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adafruit_support_bill
 
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Re: 5 Volt Problem (1.2 Kit)

Post by adafruit_support_bill »

Where do you see 5.5v?
https://learn.adafruit.com/tv-b-gone-kit/f-dot-a-q.
Do not use 9V batteries or more than 3 1.5V alkaline batteries, you can permanently damage the kit!
3 x 1.5v = 4.5v.

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1965mustang
 
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Re: 5 Volt Problem (1.2 Kit)

Post by 1965mustang »

Hello,
thank you very much for the qick help. In read in the tv-b-gone.pdf that the voltage maximum is 5,5V with a power supply. We measured 4,9 to 5 Volt but that was to high? LED number 2 is not firing yet. The rest work fine.
Is the Led burned or the Transitor?

I have make a screen shot of the passage in the pdf document.
Attachments
tv-b-gone.pdf
tv-b-gone.pdf
tv-b-gone.jpg (81.92 KiB) Viewed 2047 times

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adafruit_support_bill
 
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Re: 5 Volt Problem (1.2 Kit)

Post by adafruit_support_bill »

5.5v is an "absolute maximum". What were you using as a power supply?

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1965mustang
 
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Re: 5 Volt Problem (1.2 Kit)

Post by 1965mustang »

to provide the 4,9 to 5 Volt we took four 1,2 Volt recharge able batterieswith approx. 90% capacity. We measured 4,9 to 5 Volts.

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adafruit_support_bill
 
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Re: 5 Volt Problem (1.2 Kit)

Post by adafruit_support_bill »

Most likely it is a blown LED, but it could also be the transistor. Version 1.2 of the kit has an additional transistor driving the output stage, so it is able to push a lot more current through the LEDs. And NiMH cells have lower internal resistance than Alkaline cells, so they are much better at delivering high current. Better to stick with 3 cells max.

If you contact [email protected] with a link to this thread we can send you a new LED & transistor.

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1965mustang
 
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Re: 5 Volt Problem (1.2 Kit)

Post by 1965mustang »

Thank you for the great help and explanation. I life in Germany so I thing the shipping cost are very high for the Led and the transistor.. I have a electronic company in the neighborhood. I hope they have the parts to fix it.

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dieg0
 
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Re: 5 Volt Problem (1.2 Kit)

Post by dieg0 »

Sadly I blew a wide-beam IR-LED with the same modification. :( I've changed the power supply to 4 NiMH rechargeable batteries. I did this because it is stated in the design notes (https://learn.adafruit.com/tv-b-gone-kit/design-notes) that the maximum voltage is 5.5V. Measured voltage was 5.13V.

I've attached an photo of the LED. You can see a brownish line inside. The transistor and all the other LEDs seem to work fine.

Maybe you should change the specs so it won't happen to other people. 5.5V seems to be too high.
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LED-B-Gone_2015.01.23_23.jpg
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adafruit_support_bill
 
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Re: 5 Volt Problem (1.2 Kit)

Post by adafruit_support_bill »

Hi dieg0 - If you contact [email protected] with a link to this thread we can send a replacement led. I added a note to the tutorial regarding NiMH cells.

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dieg0
 
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Re: 5 Volt Problem (1.2 Kit)

Post by dieg0 »

adafruit_support_bill wrote:Hi dieg0 - If you contact [email protected] with a link to this thread we can send a replacement led. I added a note to the tutorial regarding NiMH cells.
The replacement LEDs came last week. Thanks for the really great service! I'll stick to 3 AA NiMH batteries now.
TV-B-Gone_3xAA.jpg
TV-B-Gone_3xAA.jpg (518.75 KiB) Viewed 1348 times

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