2 signals at a time?

ksycheng

Hey guys...

Hope everything is going well...

I am doing a project...I have a webcam, a servo motor...
First of all, the user has to define a certain colour (HSV values) and then the webcam, together with the servo motor will chase after that colour...
that part is done...

However, I want to add something extra to it...I want a speaker (an alarm) to sound as soon as the webcam loses the target...
Is it possible to send out 2 signals at the same time? 1 to tell the webcam to keep looking for the target and the other to make the speaker sound?

Thanks in advance.
Good day!

Mike Green

You might be able to make some sort of sound by outputting short bursts of sound in between servo pulses. It's probably a lot easier to use something like a 555 timer to put out a pure tone and use the Stamp to turn it on and off. Another choice would be to use one of those little piezo speakers with a built in tone generator and just use the Stamp to turn it on and off.

ksycheng

Thanks for your reply! Exactly what I need...

In what kind of stores will I be able to purchase those '555 timer' and 'piezo speakers'?
I am new to this...no idea what they are...

Thanks a lot, Mike!

Mike Green

Here is one example of a piezo buzzer that can work directly from a Stamp pin (positive to +5V, negative to Stamp pin, do LOW to pin to turn on): <http://www.radioshack.com/product/index.jsp?productId=2062398&cp=2032058.2032230.2032266&parentPage=family&gt;

The Stamps in Class tutorial on Basic Analog and Digital discusses tone generation and has a chapter with a 555 timer based sound generator. It's powered from +5V. You can simply power it from a Stamp pin (make HIGH to turn on) instead. Parallax sells the 555 timer and piezo speaker, but others like DigiKey, Jameco, and Mouser have similar parts in the on-line catalogs.

ksycheng

Thanks.

How is the loudness of the 85dB Piezo Buzzer?· I want a nice and loud tone!



Thanks again!!!

Mike Green

These are pretty loud. Look at Radio Shack's website for others that are even louder, but may need a switching transistor for the Stamp to control them (they draw more than the 20ma maximum limit for a Stamp pin).