portable amplifier help needed

[mr smellnice]

Has anyone seen those little guitar amps made out of cigarette packets? They have an input and output jack and a small (2"?) speaker - i'd like to try to make one (yes, i'm too tight fisted to pay for a new one at 25 quid!) and if anyone can help me with which bits i'd need exactly it would be much appreciated (now would be a good point to mention i'm a complete noob to electronics, though an enthusiastic one!)

thanks in advance

leroy

 

[mr smellnice]

i forgot to mention, i already have a cigarette packet...

 

[David Bridgen]

Have a look at the LM386 and TBA 820M data sheets. (Google for them.)

Both are simple to use, needing few external components.

The TBA820M will develop more power.

 

[plot]

there's the ever popular CMoy pocket amplifier you could build. i'd start out at this page: https://tangentsoft.net/audio/cmoy-tutorial/

it includes the design, step by step instructions, etc. and it fits in an altoids can.

 

[mr smellnice]

hey thanks a lot for your help - the Cmoy one looks great but the only problem is it doesn't contain a speaker (not that i could see anyway). the writer also mentions that it's not a good idea to build one if you're trying to save money unless you get it right first time - something i don't think will happen!

I downloaded the datasheets and now realise i am a complete newbie and need to do some homework first.

thanks again for the quick replies

 

[audioguru]

The CMoy amp is designed to drive headphones. Its opamp doesn't have enough output power to drive a speaker (unless you tape the speaker to your ear).
The LM386 and the other one are power amps that are designed to drive a speaker.

 

[David Bridgen]

Mr smellnice, you might like to consider a ready made one which is cheaper than the 25 quid you mention. (By the way, I've not seen the amplifiers you refer to.)

The one I have in mind is sold by RadioShack. This is a link to it
https://www.radioshack.com/product.asp?catalog_name=CTLG&product_id=277-1008

It uses the LM386.

 

[audioguru]

Hi David,
I've used that little awful-sounding amp/speaker for many years for signal tracing when I'm "out in the field".
It has a very tinny, shrill, shrieking sound quality. Something like a very cheap AM radio. It drives an external larger speaker very well and sounds much better.

As a joke I powered a large very efficient high-quality theater speaker with one of these little amps in the showroom of the speaker manufacturer. Their manager couldn't believe the quality and amount of sound that this little amp produced!
Then I unplugged his big speaker and let him hear this little guy shriek. :lol:

 

[David Bridgen]

Yes, I first made my acquaintance with them some years ago when resident in Mexico.

I have two of them into which I built telephone off-hook detectors which light l.e.d.s and, optionally, switch on the amplifier to monitor the line.

I also still have an unadulterated one but just bought another because they are so useful to have around.

Just the thing I needed in the 70s to listen to the orderwire on a microwave system I worked on. I ended up building one from scratch with second-hand components I managed to scrape together in the small desert town where I spent 6 months in Iran.

 

[Dr.EM]

I used to have that exact mini radio shack amp!

 

[GraveYard_Killer]

Mr smellnice, you might like to consider a ready made one which is cheaper than the 25 quid you mention. (By the way, I've not seen the amplifiers you refer to.)

The one I have in mind is sold by RadioShack. This is a link to it
https://www.radioshack.com/product.asp?catalog_name=CTLG&product_id=277-1008

It uses the LM386.

can the amplifier play in stereo mode or in mono mode only?

 

[David Bridgen]

It is a single channel, i.e. mono, amplifier.

You can see the features and specifications by clicking on their links in the advert.

 

[audioguru]

My little RadioShack amp/speaker plays Dolby 5.1 Surround Sound doesn't it? He, he. :lol:

 

[Dan Rodgers]

.....check out the links at www.diystompboxes.com or www.generalguitargadgets.com .......they will help you out.............dr