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transistor as a switch


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Hi Walid,
You have a very good point. ;D
The circuit can't work if R8 is there!

The supply voltage is 6.8V if the battery is fully charged.
Then the output high of the 555 is about only +5.6V.
R5 and R8 form a divide by 11 voltage divider so the base voltage of T2 is only 0.51V and so T2 never turns on since it needs at least 0.65V.

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To guru
thank u very very much you are good and expert man.

hi, just wondering, what does this circuit do?
is it just to change the output voltage of the 555?
if so what does the transistor for?

this is a part of a circuit shown in the following link:
http://www.electronics-lab.com/forum/index.php?topic=10229.0
it is an IC controlled emergency lamp with charger
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