[HELP] Laptop Speaker Design

Thread Starter

renotenz

Joined Oct 25, 2010
11
Hi all! Currently I'm trying to make a laptop speaker on my own. I've search through this forum but haven't found any simple explanations on how to make it (my bad...)

So I found this circuit which I've added to the attachment, credits to www.techlib.com

Then I've tried to simulate it on EWB, but due to uncomplete library, I've had no use of the TIP32 PNP Transistor, instead I used TIP30C PNP. I've added a Ground on the downmost node since it won't simulate if I didn't give one.

My question is why the output on 8 ohms resistor (substitute for the speaker) is only about 3 V rms on 100% Potentiometer value, as you can see at the other attachment. I used AC Voltmeter to measure it.

I used 5 V AC input which RMS value is 3,5 V. Is 5V AC a common input from sound card for an external speaker?

I've also test 1 V AC as the input, and the output is also about 3 V RMS on the 8 ohms resistor...
 

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JoeJester

Joined Apr 26, 2005
4,390
hook an oscilloscope in lieu of the meter and see the output.

sound cards typically drive headphones. lower your input voltage until the oscilloscope shows no distortion.
 
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