Odysseas

Hello everybody,

since this is my first post in this forum, I'd like to introduce myself, first. I am an apprentice for eletronics at a quite large computer company in southern Germany. Eletronics has been a hobby of mine for a year or two, but as the proverb states: The more you know, the more you know that you know nothing. So I came here to expand my knowledge. I have been quite active at german forums about electronics before, but unfortunately I've had to come to the conclusion, that all members there are either unexperienced by themselves, or extremely arrogant. They're so arrogant, it's impossible to work with them. So I hope I will find polite and benevolent people here, just as I seek to be.

Okay, enough about me, here's my problem: I want to built a music unit for at work (work can be very dull without music, huh?). It should have a small amplifier (2x5 Watt RMS @ 4 Ohms should do) with acceptable quality. It should also have a radio unit integrated (my favourite surplus store does the TDA 1596 and TDA 1574, anybody some experiences with one of those?), of course, it would be cool if I could control this digitally (Atmega?). The next thing is an auxilliary audio in (for my mp3-player), with a stabilized 1,5 VDC out to replace the mp3-player's battery. The whole system should also not draw too much power from the outlet, otherwise I risk that my employer gets mad at me... So the overall system efficiency should be kept at the maximum possible, even if I have to use more expensive parts for that.

I think the biggest problem will be the radio receiver. Has anbody ever done a radio receiver, either with digital or analog controls? Any reports would be appreciated.

Thank you very much.

Odysseas

HarveyH42

Welcome to the forum. First, I'd like to appologize for the British... Just kidding, but you'll find this to be multi-cultural, and thus different interpretations of 'polite', just be tolerant, it's not so bad and sometimes amusing.

Find the data sheet for your amp chips, they usually have the basic hookup already to go, and good enough for most people. Give you a link for datasheets, but it hasn't worked in a while (might be my computer and PDFs).
For the reciever... Why not go ready built? Lot less headache, cheaper, and like better functioning then anything we could build from scratch. I've seen some about the same size as an MP3 player for $2.00 surplus, the earphones are worth that.

Now, the 1.5 VDC power supply is of interest to me as well. Haven't found a good way to drop a higher voltage, without a huge waste through a resister or regulator. But mine is solar-battery applications.

Odysseas

That's worth a thought, where've you seen that? My favourite surplus doesn't have that, or at least not that I have noticed it. You have a link?


Once I've read that with a NE555, a coil and some other very few parts, one can easily construct a quite efficient mini-switching power supp - but I dunno how. But they claimed they could easily assemble it on a 4cm x 4cm (1.57 x 1.57 inch) perfboard. Once we have about two volts, we can go for an LM317 to get some stable 1.5 Volts, power wastage should be acceptable then, huh?

HarveyH42

http://www.allelectronics.com/index.html
http://www.sciplus.com/index.cfm
http://www.bgmicro.com
http://www.goldmine-elec.com/default.htm

These are the surplus site I watch closely. I didn't check to see if they have anything in the radio department, sure one will have something.

Yeah, I've seen several switching supplies for LEDs, but usually there is an inductor to be wound on a ferrite core. No cores, and could only guess on the wire guage I have on hand. I've got some circuits on my hard drive, will post when I find them.

Odysseas

I've checked some others sites, and found a very cheap radio, that would support digital scanning. But to be honest: I know this shop. Most of the stuff sold there does not life very long. I think I'll have to go for something self-made...

I will check thru all radio receiver ICs I find, see if I can get any useful results...

About the amplifier: I've found this
pretty nifty looking schematic, that seems to provide quite some power, and appears good quality. D'you think I can go for that one? And will I be able to use a 2x 12 VAC torroidal voltage, that yields some 18.8 VDC with no load?

audioguru

Don't buy a cheap radio, and don't make a simple IC radio. They sound like crap, are mono and have poor reception.

The amplifier project you found uses many parts and is complicated. A modern stereo bridged power amp IC that is made for cars like a TDA1554 would be better, much simpler and less expensive.

__________________
Uncle $crooge

Odysseas

Well, what is the alternative to radio ICs?

Nigel Goodwin

An obvious easy (and cheap) solution would be for you to buy a car radio and use that?.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

HarveyH42

You should go with what suits your needs. Some people aren't satisfied unless it sounds precisely like a live band. Since this is for at work use, and most likely just a little background sound, most any reciever would be okay. You didn't mention if this was more for you personally, or music for an entire office or warehouse. Guessed it was just for you, since the minimal power usage. A car stereo is probably over-kill, might as well use a PIC . To power it would be considerable.

I do remember an FM radio chip years ago, didn't seem to need many external parts, but don't remember who made it.

audioguru

Philips make an "FM Tuner on one chip" that is surface-mount-only now. It is crap and is copied by the Chinese who make the lousy FM "radios" for sale in Dollar Stores. It makes a 1st radio for a 6 year old kid.

I have a Sony AM-FM Stereo Walkman radio that was inexpensive and designed to drive headphones. With a DIY stereo amplifier and a pair of DIY little high fidelity speakers it sounds great.

__________________
Uncle $crooge