Transistor LED Circuit with Mobile Sound Control | DIY Guide

[asa!!]

Hi guys, i want to fix a circuit that will use a led and i want to use a transistor as the switch to the led. I would like the base current to be produced by a sound played throug ha mobile. A sound turning the light on and the same or other sound turning it off. No ideas how to do it.Thank you for your help.any ideas are welcomed
asa!

 

[berkeman]

Check out this thread from a couple weeks ago:

https://www.physicsforums.com/showthread.php?t=78945

In my last post at the bottom, I show a circuit that turns on a red or green LED based on the battery voltage (as a low-voltage indication). The two cross-connected transistors at the right would be how you would normally make a small 1-bit memory cell that can turn on an LED in response to something, and then turn it off in response to something else. By turning on one transistor, that shuts off the other transistor.

Now you just need to figure out what you want to do with your input signals to generate the base drives for the two transistors. For example, you could low-pass the music to generate one base drive signal, and high-pass the music to generate the other base drive signal. Then different tones in the music would turn the LED on or off. If you leave two LEDs in the circut like for the low-batt indicator, you'll get a mix of colors based on the music content.

 

[ravenprp]

Hi there,

Thank you for your question. It sounds like you are interested in creating a transistor LED circuit that can be controlled by sound from a mobile device. This is definitely a fun and creative project to work on!

To start, you will need some basic electronic components such as a transistor, LED, resistors, and a power source. The type of transistor you use will depend on the type of LED you have and the amount of current it requires. You can refer to the datasheet of your LED to determine the appropriate transistor to use.

Next, you will need to connect the LED to the collector of the transistor, with a resistor in series to limit the current. The emitter of the transistor will be connected to ground, and the base will be connected to the audio output of your mobile device. You may need to use a capacitor to block any DC signals from the audio output.

When a sound is played through your mobile device, it will produce an AC signal that will be amplified by the transistor and turn on the LED. When there is no sound, the transistor will be off and the LED will be off as well.

You can experiment with different values of resistors and capacitors to adjust the sensitivity and response of the circuit to sound. You can also add a potentiometer in series with the base to control the threshold at which the LED turns on.

I hope this helps get you started on your project. Remember to always be safe when working with electronics and have fun exploring and learning along the way. Good luck!