simple kiosk sound system design

[pigeon]

Hello, I am looking to design a PCB to handle the 3.5mm output of a computer then boost that signal to run standard"" speakers (simple $6.00 per car speaker at walmart ones).

The reason I don't want to use standard computer speakers is because I like the mounting holes for the car speakers, and besides that, at $6.00 per speaker (and I really wouldn't only need one speaker), I could get away with a really inexpensive setup.

Also, this system will only need to handle midrange... the kiosk will 'talk' to people, no heavy bass or high highs.

Does anyone have any suggestions?

I have been looking at radio shack for amp chips (I am not evensure that is the right name), but I have found LM324 chip... but I am afraid (?) that it will not be powerfull enough.

The ability to have the speakers be really loud would be a plus, but not necessary.... Also, I would like the ability to regulate the volume somehow (on the pcb)


Are there any inexpensive solutions (under 15$ for speakers + pcb + parts)?

thanks
Lee

[carlosfm]

Originally posted by pigeon
Are there any inexpensive solutions (under 15$ for speakers + pcb + parts)?

Hey, where are they giving away those parts?
Are you serious?
A trafo costs more than that.
You don't need a big one, but still...

[homer09]

well since sound quality is the least of your worries, i would suggest locating an electronic surplus store in your area. you dont need much to get one channel simple chip amp working.

start with finding an LM or TDA chip that gives you the power you need. take the datasheet for it, and just p2p an amp. i dont think a PCB is necessary, and it will blow your budget. most of these chips need half a dozen caps and resistors in all to make a working amp. add a cheapie pot infront, and you have yourself what you need.

oh for power supply, see what your surplus store has lying around, and work from there. with 4 cheap diodes you have yourself a powersupply. but of course, dont forget to snubber it

im sure you could find the appropriate connector to accept 3.5 mm jack from computer and connect to pot. if not, just buy a cable with 3.5 mm jacks, cut one end and directly connect to pot and sound card.

[cowanrg]

agreed. surplus stores will be your friend with this one...

i built a gainclone way back in the days in a cardboard box for $40 for a stereo one with decent parts and dual power supplies.

its "possible" to do what you want, but i would shoot closer to $30 for a budget just so you dont completely sacrifice things. little bits and pieces always add up ($1 for 3.5mm connector, wires, ac input cord or jack, etc...).

[homer09]

also agreed. $15 is a bit too stingy if you have to buy everything new. if you are like most of the people here and have closets filled with junk/unused parts, than $15 isnt even necessary

[cowanrg]

exactly. it all depends on what you have. i built a pair of aleph3's with cases, caps, etc... for $350 for two monoblocks. you could NOT do that if you didnt have stuff laying around. all the wire, caps, fets, resistors, and other bits and pieces were just already in my shop. i just added transformer, case, and some other stuff.

resistors and caps for a chip amp are practically free (if you get them surplus or have them), the chip it self costs some cash, and the transformer will be the other cost (but you can get these for $5-$10 if you are lucky. but you will need a case, connectors, wire, etc...

$30 sounds like a fully built amp.

[Bill Fitzpatrick]

Why not just pick up a cheap amp at a thrift store, use the Walmart speaker and be done with it.

[homer09]

Originally posted by Bill Fitzpatrick
Why not just pick up a cheap amp at a thrift store, use the Walmart speaker and be done with it.

yeah, sometimes DIY gets to my head. im sure you could find a working cheap amp with plenty of juice for less than 30 at any thrift shop.

[cowanrg]

like this:

http://www.allelectronics.com/cgi-bi...-30&type=store

30-watts stereo for $19. includes everything you need. and a pair or more is only $15 each! what a deal...

[neutron7]

probably still cheapest to just use the guts fromn some self powered computer speakers and take them out of the box and hook them up to your car speakers.

does the kiosk have to pass UL certification or is it a one off.