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Power Speakers Without Opamp?

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jcremes

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Is it possible to power a speaker without the use of an op amp? I'm making a speaker system for my iPod, and I'm kind of snowed in so I can't buy an opamp, yet my ipod won't have the power to amplify the speaker, is there another way I can power the speaker?
 
You can use discrete transistors.

How much power do you need?

What's the impedance of the speakers?
 
Go to a Salvation Army Thrift Store or Godwill. You can probably find a set of powered PC speakers for $5. They will work unmodified. If you are really lucky, you might even find a PC subwoofer.
 
If I could drive to Salvation Army, I could probaly drive to radioshack as well. But as I said, I'm snowed in. But Hero999, it's impedance is only 3 ohms, so I won't need that much power.
 
That sounds odd, I've never seen a 3 Ohm speaker before, are you sure that's right?

Normally lower impedance speakers are higher powered, generally 4 Ohm speakers tend to have higher power ratings than 8 Ohm speakers which have higher power ratings than 64 Ohm speakers etc.
 
Car speaker... What's it's power rating? The ohm rating has absolutely nothing to do with the power capability of the speaker directly, though Heros generalization is very accurate. You could make a simple class A amplifier if you have a suitable power transistors and resistors.
 
What kind of stash do have there to work with? How much volume are you looking to make.
 
I'm not looking to shake my house or anything lol. But probably about the same amount of volume as an iHome cranked all the way up. And I have a pretty large stash to work with.
 
The physical bulk of it will say a lot... Can you take a picture, and guess at it's weight?
 
I would say it's 14 ounces to a pound, give or take.**broken link removed****broken link removed**
(CD case is just there for scale)
 
somewhere i saw a schematic for a crappy audio amp with just transistors it had a pre amp that looked similar to a fuzz face, and the power amp was a darlington pair of transistors driven by a 9v batter. im sure is sounds like a cheap japanese 1960s transistor radio but it should make sound.
 
theoretically even one transistor a few resistors and a 9v battery could power a speaker. if you have a line signal from somethign already connect it to the base of a transistor and connect the speaker and the transistor to a 9v battery trying a few different resistors values . but a 9v battery is enough to make speakers go pop and extend al lthe way. between the emitter and collector of the transistor will act like a potentiometer controlled by the voltage from your audio signal at the base. so your line audio signal swithches the the 9v to the speaker o nand off exactly the same as the signal form the the line. obviously its going to be noisy and have distortion radio interference etc etc. few capactors could remedy that.
 
It would be more reliable if it had emitter resistors in the output stage. In this case I would use 1.5 ohms each.
 
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