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Transistor-resistor connection

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harrisonic

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pls help!!!!

how this circiuts works?
and what is the purpose of R3 connected to the base of Q3?
also the R2 connected to Q1,Q2?

pls anyone can help me
 
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where did this cct come from. it doesnt look right to me

firstly to answer you question R2 from the output of the 555 to the base of Q1 and Q2 is basically just a current limiting resistor.

I doubt that R3 should be going to the base of Q3 it should be going to the common collectors of Q2 and Q3 ... these 2 transistors are connected as a darlington pair. As it is currently wired, Q2 and Q3 cannot ever operate as there is no voltage supplied to the collectors.
The upper set of LED's D4-7 cannot be turned on via the emitter of Q3 as its a NPN transistor. The conduction in that transistor should be from collector to emitter, as in the way the lower set of LED's are turned on via Q1.

definately a screwball cct
as I said where did it come from ? if from a www site, was there a cct explanation ?

cheers
Dave
 
aye!!! i just get it in the www site. @ instructable.com and their is no cct explanation

btw thanks for the help...
 
Wow per Audio Guru we clearly have a case of Deja Vue all over again :) .

What part of the last thread with the same incorrect circuit did you not quite understand? You will get the same replies as the last time. Audio Guru has been kind enough to redraw the circuit and point out the same errors pointed out the last time.

Ron
 
Harrisonic does not understand how a simple transistor switch works.
He also uses software that makes a schematic a negative image.
 
Dear Mr. AG

Harrisonic, does not understand how a basic transistor works and this is what happens when one jumps from EL101 to EL103 without grasping the basics. Harrisonic, is but one of 100 recent post along those same lines. This runs with a joke I started and share with one of my company's most senior and knowledgeable engineers. When I see Jim I often say: " Jim, I am free Tuesday afternoon for a few hours, can you teach me everything you know. I want to be an engineer when I grow up". We always share a good laugh on that note.

Ron
 
Dear Mr. AG

Harrisonic, does not understand how a basic transistor works and this is what happens when one jumps from EL101 to EL103 without grasping the basics. Harrisonic, is but one of 100 recent post along those same lines. This runs with a joke I started and share with one of my company's most senior and knowledgeable engineers. When I see Jim I often say: " Jim, I am free Tuesday afternoon for a few hours, can you teach me everything you know. I want to be an engineer when I grow up". We always share a good laugh on that note.

Ron

Reloadron, I am free Friday afternoon for a few hours. Can you teach me everything Jim taught you the day before ?

:)
 
Sure, could likely get it done in an hour then have a few beers.

Ron
 
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