spinning leds

[harrisonic]

how does this circuit works especially the transistors operations? pls someone help me!!!...View attachment 60373
im new..

 

[Diver300]

Quite simply, it won't work. Q2 and Q3 are the wrong way up. The emitter of both of those should be connected to earth, and the collectors should be connected to where the emitters are shown.

Well it might work, but only because it could be that transistors will sort of work when fitted the wrong way up. In this case the transistors are not running near their limits, so it won't matter that they perform far worse than they could.

Also, there should be a separate resistor to feed the base of Q1 and Q2, they should not share one resistor, because the current into the base of the transistors will not be shared anything like evenly.

The output of the IC, which is probably a 555, alternates between 0 V and 6 V. When it is at 6 V, current through R2 turns on Q1 and Q2. The collector voltage in Q1 then falls and LEDs 1,2,3,8,9 and 10 light.

The collector voltage of Q2 also falls, and that causes Q3 to turn off, so LEDs 4 - 7 turn off.

When the output of the IC is zero, Q1 and Q2 turn off. That turns off LEDs 1,2,3,8,9 and 10. Q2 turning off lets the current through R3 turn on Q3, so LEDs 4 - 7 turn on.

 

[4pyros]

Did you get that from a web site? If so post link.

 

[harrisonic]

thanks for the help...but one more thing..does that mean Q2 is just for interrupting Q3?..
i mean current interrupting on Q3?

 

[harrisonic]

yes i get it in the instructables.com its titled(spinning rainbow wheel)

https://www.instructables.com/id/Spinning-rainbow-light-wheel/

 

[harrisonic]

thank for the help

 

[Ian Rogers]

That's not the circuit posted..... Q2 and Q3 are wired incorrectly.... these are a simple inverter so the lights flash in sequence.

 

[4pyros]

That's not the circuit posted..... Q2 and Q3 are wired incorrectly.... these are a simple inverter so the lights flash in sequence.

Would that be "flash alternately".

 

[Ian Rogers]

Yep! That's what I really meant... Thanks for pointing that out 4pyros....