Path of least resistance right?

Thread Starter

VictoryLap

Joined Oct 3, 2019
5
So I've built a buffer using:
- 3.3V power supply module
- 1 Yellow LED(left)
- 1 White LED(right)
- 2 220 Ohm resistors
- 1 1k Ohm resistor
- 1 2N3904 NPN transistor
- 1 jerry-rigged button (push to close)

But for some reason, I can't understand the white LED won't turn on when the transistor turns on.



Leave a comment here or on my youtube video on why I am wrong in my thinking lol.

thanks,
a circuit newb
 

MrChips

Joined Oct 2, 2009
19,382
The two LEDs and two resistors are all in series. You do not need two resistors.
You need to show where the -VE side of the first battery is connected.
 

Thread Starter

VictoryLap

Joined Oct 3, 2019
5
Thank you MrChips! I guess my math was wrong? I just tested the positive rail with that leads into the white LED(ultimately into the collector) w/ 5V and works like a charm!

but when you say I don't need 2 resistors are you referring to the fact that I could use a 1.2k ohm resistor instead of a 220 and 1k?
 

MrChips

Joined Oct 2, 2009
19,382
Ok.
Use one LED on the collector of the transistor.
The 1kΩ resistor on the base is ok.

You can increase the 220Ω resistor to make the LED less bright.
 
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