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Music LED Sync? Answered

for the circuit in the pic can I use the transitor listed here  instead of TIP31, SMD LED Strip instead of the 4 LEDs, and can I power it with an ATX Power Supply as it also has 12v DC output????
Thanks in Advance.....

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steveastrouk
steveastrouk

7 years ago

I can't see the transistor you're interested in in the link, but here you won't need high power handling, you just need a high gain - shoot for Hfe >>500.

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adarshnarsaria
adarshnarsaria

Answer 7 years ago

Do you mean forward current transfer ratio (hFE)???

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adarshnarsaria
adarshnarsaria

Answer 7 years ago

Will a forward current transfer ratio (hFE) of min: 20 will do???

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steveastrouk
steveastrouk

Answer 7 years ago

I SAID
"you just need a high gain - shoot for Hfe >>500"

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adarshnarsaria
adarshnarsaria

Answer 7 years ago

HFe >> 500 means less than 500 (>> = Less Than)?????

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steveastrouk
steveastrouk

Answer 7 years ago

VERY (hence >>) much GREATER THAN.
BASIC maths.

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adarshnarsaria
adarshnarsaria

Answer 7 years ago

well but tip 31 itself has hfe of min 20???
Then how come the world is syncing their LEDs to music with those TIP31s ???

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steveastrouk
steveastrouk

Answer 7 years ago

Its a dumb choice. Just because lots of people use it doesn;t make it less of a dumb choice.

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adarshnarsaria
adarshnarsaria

Answer 7 years ago

well, will these do??
http://alltransistors.com/crsearch.php?mat=Si&struct=NPN&pc=40&ucb=80&uce=40&ueb=5&ic=3&tj=150&ft=3&cc=0&hfe=500&caps=TO220

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adarshnarsaria
adarshnarsaria

Answer 7 years ago

okay i got that and I am really very sorry for being stupid....

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iceng
iceng

7 years ago

You need a series resistor with the LEDs

this is how.

a gain.gif
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iceng
iceng

Answer 7 years ago

Or a better circuit

aa gain.GIF