Would like to build super simple mini transistor amplifier

[Coconuts 500]

Hello!

I want to build a tiny transistor amplifier, using very few, cheap and commonly available parts (no opamps or ICs). Basically something with regular TO-92 style transistors, or similar. Powered by a simple 9-12 volt wall wart. Just a power switch and a passive volume control. Sound quality is not important, but a bonus. Basically I want to build something like the amp found in cheap computer speakers.

I've been looking around and cannot really find what I need... Does anyone know where I can find a pre-made schematic for something like this?

Thanks!

[DF96]

Look at late 1960s/early 70s radio/electronics magazines. They were full of this sort of thing.

[Wakh]

[qusp]

Originally Posted by Coconuts 500

Basically I want to build something like the amp found in cheap computer speakers.

but that would be an opamp/IC

[diy didi]

Do a search on the net for Sinclair Z30. Remember to add emitter resistors.

[sofaspud]

You might consider the circuits on this page.
With a name like Fun With Tubes the site can't be all bad.

[john_ellis]

Are you still there?
Here's a simple output stage I used for a tranny radio. Works well.
John

[sreten]

Originally Posted by Coconuts 500

Hello!

I want to build a tiny transistor amplifier, using very few, cheap and commonly available parts (no opamps or ICs). Basically something with regular TO-92 style transistors, or similar. Powered by a simple 9-12 volt wall wart. Just a power switch and a passive volume control. Sound quality is not important, but a bonus. Basically I want to build something like the amp found in cheap computer speakers.

I've been looking around and cannot really find what I need... Does anyone know where I can find a pre-made schematic for something like this?

Thanks!

Hi,

Your misguided. You can't build an amplifier just using small signal transistors.
Its stops being simple very quickly when you realise just how rubbish your
simple amplifier is compared to simple IC circuits that have been around
for years, and for good reason, they are simple, and they work well.

No computer speakers use an amplifier of your description. The latest use
mini class d driven from the 5V supply of USB ports. Older ones almost
exclusively use chip-amps. With a 12V supply your talking car audio
and there is simply loads of options, around 5W / 4 ohms for a
simple circuit and up to 20W for bridged into 4 ohms.

IMO just buy a cheap kit off e-pray.

rgds, sreten.

[Bigun]

- this is DIY, no kits! There's a truck load of web sites with simple amps. And power devices may not be so critical if listening to small speakers at low volume - when I listen to my computer speakers I'm guessing they're playing at 1/8 W. But it is a stretch when a couple of power transistors can be had cheaply these days - even a pair of old 2N3055's from an old power supply or something.

http://www.electro-tech-online.com/d...datasheet.html

http://musicouch.com/instruments/str...mple-receiver/

[Elvee]

Here is an original proposition.
Despite its simplicity, it even manages to include an auto-bias circuit: