AVR-Chat

On Jun 21, 2008, at 10:33 PM, xolang1 wrote:

> hello,
>
> I have 2 requirements that i hope someone could help me on:
>
> 1) I have a certain circuit that is able to drive an 8Ohm speaker  
> with a maximum output of 1watt. the voltage output is measured from  
> 0 to 5V. The sound however , is quite soft and I need to install  
> this inside a vehicle which is expected to be noisy. I need this  
> audio output to be amplified to some good degree (about 10 - 20watts  
> to my estimate). The Amp has to be of high fidelity as the output is  
> not of the best quality. My problem is I am not familiar with audio  
> circuitry and there seem to be numerous solutions on the web. can  
> anyone recommend a good solution, possibly 1 single chip solution  
> that does all the analog handling and is powerful enough to drive a  
> 10 - 20w speaker. Also, is it possible to connect the speaker ouput  
> of my current set up to this amp dirrectly without worrying about  
> impedances etc?
>                                                                       ???
> audio circuit-----(output is good for 8Ohm skr)---------------------- 
> >10-20w Power Amp
>

The TriPath based AMP3 or AMP32 amplifier boards from 41hz.com put out  
up to 25W per channel (they're stereo) with very high fidelity. I  
bought one as a kit for a project.

They'll drive a typical speaker setup just fine, and will run from an  
automotive 12V source.

They're in Sweden and take PayPal. It can take a couple of weeks for  
airmail to the US, but I was pleasantly surprised (about a week as I  
recall). If you're in the EU it should be within a week.

http://www.41hz.com/main.aspx?pageID=105
The AMP3 kit is about $34 (depending on how weak the US Dollar is when  
you order it).

>
>
> 2) I need a vibration sensor that is able to detect strong  
> vibrations in a vehicle (e.g. when the tires hit a hump). ideally  
> this solution in also single chip.output could be a simple ttl logic  
> or analog voltage.
>
>
> If possible, solutions that can be bought individually like from  
> arrow / digikey would be best as this is only for hobby-grade.
>
> any help is much appreciated.
>

Mouser doesn't charge for smaller orders like DigiKey does.

The MSI LDT series piezo elements have a relatively high output  
voltage; they have a version with a weight riveted on which is more  
sensitive. They're about $1.00-$1.50 each in single quantity from  
Mouser.

http://www.mouser.com/catalog/634/1808.pdf

http://www.meas-spec.com/myMeas/MEAS_download/datasheet/pdf/piezo/ldt_series_elements_lead_attachment_lamination.pdf

These look electrically like a capacitor and should be connected to a  
high-impedance circuit.

-- 
Ned Konz
ned@bike-nomad.com