Audible warning system?

[nocam1334]

I work for a company that rents and sells pumps and we've been discussing trying to incorporate some sort of audible warning system for when something goes wrong with one of the pumps. We actually have a system in place that alerts us when something goes wrong, but no audible alert.

I know greeting card companies have little players in their cards, I was thinking about incorporating something like that into one of our control panels. I'm thinking this might be a relatively cheap and simple solution.

I'm a mechanical engineer, so I only have a very basic understanding of the electronics and wiring. Can any of you offer any advice on what I might consider using and how difficult this would be to implement? Thanks.

 

[GonzaloEE]

nocam1334, right now, I have no idea how much would it cost, but considering your audio amplifier won't be like Hi-Fi, you may try with lower bitrate MP3 for a smaller memory usage. For example, a 2sec. voice message recorded at 128kbps (CD quality) needs some 32KB of memory space, though at 32Kbops you get decent AM radio-like quality, or telephone at 11Kbps.

OK, just in case these cut&paste design 'procedures' are hurting some basic Engineer's principles I'd suggest to make an embedded board with some midrange processor/DSP/etc, SD-card or on-board flash, and some integrated audio stage.

Of course you'll have to build the firmware for MP3 decoder, or interface the CPU to some MPEG L3 decoder chip, etc. Also, you have to define how to upload your files: CPU-interface, USB + file system to load files from your computer, etc.

If you're going for the 'hack & paste', check in advance which bitrates your player support. There are plenty of WAV2MP3 conversion s/w on Inet if you're going for a more decent, embedded solution.

Good luck!

 

[VEBill]

If you must create a bespoke solution and the device is going to have a one- or two-word vocabulary, then skip MP3 and all that and just have it spew out a simple wave file on command. The wave file is likely smaller than the MP3 routines. With some clever programming (using PWM) the audio stage might just be a digital output pin connected to a series capacitor and the speaker.

 

[dbaird]

Look at:

http://www.patlite.com/index.php?ma...ain_category_id=2&category_id=14&product_id=9

David Baird

Sr Controls Designer
EET degree.
Journeyman Electrician.

 

[GonzaloEE]

I heard of a college mate who made a simple audio file player with something like what VE1BLL suggested. He downsampled a WAV file with MAtLab to match the bitrate to his uC clock speed. Then made a simple PWM program with pulse widths directly taken from WAV sample values. The rest was just wiring: a RC filter and a walkie-talkie audio amplifier IC.
Sound was horrible, like robotic, but you could tell the messages.