Please help me solve this doubt

Thread Starter

paldep

Joined Mar 3, 2016
41
I built this circuit using a red led ,a tip131 transistor and a battery of 3.7 volt. Nothing happens. But if i Connect a dc motor from a cd player in parallel with the led it works. How is it possible? What the dc motor does to the circuit?C__Data_Users_DefApps_AppData_INTERNETEXPLORER_Temp_Saved Images_images5Y3SBMKJ.jpg
 

AnalogKid

Joined Aug 1, 2013
8,488
The image is so small and fuzzy that there is not any detail. Please post one that is larger and more clear. Are there any resistors in the circuit anywhere?

ak
 

TheButtonThief

Joined Feb 26, 2011
237
What's with the headphone connector attached to the base and emitter?

It's a very odd looking circuit. Where's the current limiting resistor for the LED's? Where's the base current limiting resistor? Where does the headphone connector go?

Your motor is providing a resistance between the collector and emitter and saturating the base of the transistor, it's in open circuit without the resistance of the motor coils.
 

Dodgydave

Joined Jun 22, 2012
9,206
Leds need a series resistor to work properly, otherwise they will burn out, try putting one of them across the battery with a 100 to 470ohm resistor in series.
 

Thread Starter

paldep

Joined Mar 3, 2016
41
The headphones connector goes into an mp3 ipod . I plug it to the output of an amplifier.
When there's a peak of 0.7 volt the led start to blink. But without a resistor the led will burn. Thank you guys.
 

TheButtonThief

Joined Feb 26, 2011
237
I'm sure there are plenty of other circuit examples out their in the googleverse that'll actually work. The one you've posted lacks some fundamental components and I'm not suppressed it doesn't work.
 

Thread Starter

paldep

Joined Mar 3, 2016
41
Can someone draw me a circuit that use a 5 volt source using a transistor a red led and all the necessary components? Thanks
 
Top