Output a beep

[nightdesigns]

I would like to output a beep sound.  I'm guessing I need some sort of speaker with a relay control, but I'm not exactly sure what I need to look for.  Can someone point me in the right direction?
 
Thanks

 

[nightdesigns]

To add: looking to do something similiar to the sound a home alarm panel makes when a door opens (the alert sound that a sensor has been tripped, prior to full-blown alarm)

 

[jpmargis]

Check out the various types of Sonalerts that are available.

 

[CAI_Support]

If you have a relay board, you can use almost any beeper, or even siren.  TTL output is limited to 20mA per output pin, or 100mA for all the TTL outputs.
How loud do you want the beep sound? If not too loud, you could find a lot of little buzzers at www.allelectronics.com under buzzers
Somehow I was not allowed to post URL, so I can only type the domain name, I am sorry for that.

 

[donv]

I just received one of these: http://www.ebay.com/itm/small-3-3V-5V-Active-Buzzer-Alarm-Module-Sensors-/251165904421 and it seems to work fine. You can't beat the cost, I think the parts alone would be more than the assembly. Unfortunately, there is no current spec on the listing so I don't know what it wants to draw.
 
I'm still new to the WebControl board and figuring things out. I wired this board as follows temporarily:
GND = Output GND
VCC = 5v pin of humidity sensor
I/O = Pin 7 of output
 
It operates differently than I expected - when TTL7 is 0 it sounds. TTL7=1, quiet. I wonder if I got the wiring correct. If so, I can adjust my PLC code appropriately to keep it high nominally but would prefer to not draw current unless the alarm is required.

 

[MobileMe]

Looks like you have it wired correctly. That is just how the transistor operates.  I never really liked those kind of circuits either.  However, I don't think it's drawing very much power. 
 
You can invert the state in the I/O setup page last I checked.

 

[CAI_Support]

MobileMe is correct. that particular board has a transistor on it, and it inverted the input to the opposite polarity.  To use this buzzer, you will need to go to IO SETUP screen, then check invert output for TTL output 7. 
 
That may have a side effect, when WC board lost power, your buzzer will keep beeping.

 

[MobileMe]

If you're using power from the board, when the board is powered off the buzzer will not go off.  However, when the board is first powered on it will go off until the plc code corrects it.
 
You can always bypass the transistor altogether and just use an output to drive the buzzer.  A little soldering and some wire would do the trick.

 

[donv]

Thanks. Sounds like just inverting the output will be the easiest solution for now, but if I have a slot left on my relay board when I'm done that will be the long term one.