How Can I Build a Basic Transistor Amplifier for My Phone's Speaker?

In summary: You could try a 2 transistor approach, but you would need to add a power supply. In summary, to make a basic transistor amplifier that can give decent volume from a speaker, you would need to connect a device to an IC, or use resistors.
  • #1
ajbwarrrior
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Hi,
I have a single 2 watt, 8 ohm speaker from an old radio that i wired directly to a headphone audio jack and tried it in my phone. as you can probably guess, my phones speakers are much louder.

How could i make a basic transistor amplifier that could give decent volume from the speaker?

I have seen many circuit diagrams for this but i don't know how a device would be connected to them.

Any schematics that would suit this application would be greatly appreciated.
 
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  • #2
You can do it with opamps, or discrete transistors. I'd recommend opamps. Just look at google images for audio amplifier IC and start reading about an approach. Note that amplifiers require a power source which can be as simple as a wall wart.
For example:
http://www.rason.org/Projects/icamps/icamps.htm
 
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  • #3
with the amp in the link, how would the input be connected to a 3.5mm auxiliary jack ?
 
  • #4
The link shows a mono amplifier. The 3.5 jack has three rings, ground, left, and right. You would connect ground to ground and either left or right to the amp (or use a stereo IC with 2 amps). Or, you could make a resistive mixer where you connect both L and R to the input, each through, say, a 1K resistor.
 
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  • #5
  • #6
I don't think that will work for what you are doing. It requires the proper DC levels on the input, and drives a continuous DC signal through the speaker when there is no signal. It is a pretty specialized hack for his radio application.

Look at this page --- Question 5 is probably the simplest design that will work, question 8 shows a 1 transistor approach.
http://www.allaboutcircuits.com/worksheets/trouble_bjtamp.html

The problem with the 1 transistor approach is that the speaker loads down the amp.
 

1. What is an amplifier?

An amplifier is an electronic device that increases the amplitude or power of a signal. It takes a weak input signal and produces a stronger output signal.

2. What are the components of a basic amplifier?

A basic amplifier consists of three main components: an input signal, an amplifying element, and an output signal. The amplifying element can be a transistor, vacuum tube, or integrated circuit.

3. How does an amplifier work?

An amplifier works by taking an input signal and increasing its amplitude through the amplifying element. The amplified signal is then sent to the output, which is a larger version of the original input signal.

4. What is the difference between a voltage amplifier and a current amplifier?

A voltage amplifier increases the voltage of a signal while keeping the current constant. A current amplifier increases the current of a signal while keeping the voltage constant.

5. What are some common applications of amplifiers?

Amplifiers are used in a variety of electronic devices such as audio systems, televisions, and radios. They are also essential in communication systems, medical equipment, and scientific instruments.

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