Rule against Sirens?

Good evening, CD!

I just picked up a RadioShack 273-079 12VDC Piezo Siren from (guess where) RadioShack, in hopes to integrate it into our DS. After hooking it up to a supply, I have come to realize that this siren is VERY loud. This is ideal for a competition setting, as it will certainly get the driver’s attention. My question is, are there any rules against creating noise from your DS (or robot for that matter)? I did a quick skim over the rules again, and couldn’t find anything, but wanted to make sure.

Also, is there anyway to control volume for a piezo buzzer? Something tells me no (I’ve tried varying voltage with no avail), but I figured I’d ask.


EDIT: after reading, it looks like maybe I can use PWM to control the volume.

i would say dont do it

102db is well up into the “unsafe for your hearing” levels. If you can’t mute it go find something quieter. You are likely to be disqualified for operating a robot that creates an unsafe environment for people. (I didn’t bother looking up the rule number. If there isn’t a rule against it, it’s still wrong – it shouldn’t pass inspection, and a referee should DQ it should it appear on the field.)

Not that the music at some venues doesn’t exceed 100db, but that’s another perennial thread that I expect will show up soon.

Controlling the volume is easy. Just put it in a box. Close the box for quiet, and open the box for loud. Add padding around it to muffle it effectively.

Thanks for the responses. I guess my question now is, if I can find a quieter siren (80 dB or so), is there a rule that prohibits the use of this on the DS?


I’d advise against a buzzer… i dont know of any rules specifically against it, but i know that you cant have any sound systems on the cart… It may be distracting to other drivers

If you plan on using it on the driver station, you’ll have to keep in mind that the DS only outputs 3.3V (I think).

I wouldn’t recommend it, though I would say if you find one quiet enough to be heard it’d be ok. I think it would overall be better to have your programmer put something on the Dashboard and have the coach/driver take a looksie at it now and then. Or a giant light.

Being a driver and one who is very jumpy (ask anyone on my team), I wouldn’t like it very much if I got scared during a match.


We use a rumble pak that vibrates when we grab a ball. That doesnt make much noise and gets the drivers attention (they never look at LEDs). We used the rumble pack last year to indicate when our turret sees the target. I have heard other teams use them as well (not sure who). Rumble paks are easy to reverse engineer to work with a digital out (heck if convicts can figure out how to maketattoo guns with them, then it shouldn’t be too difficult for a young engineer).

I will not say anything about safe noise levels (no one would take me seriously coming from a team that gotloud noisemakers banned :wink: ). However, I believe audio cues should be taken from the coach only, not the control system.

We have a 12V supply on our DS, which is the regulated to feed our USB hub among other custom circuits. I have installed a light that is triggered by the same function that the buzzer would be triggered by, it’s just a very worst-case scenario type of thing that requires immediate attention (things breaking themselves, essentially an indicator to hit the E-Stop). Following Alan’s suggestion, I’ve padded the siren, and now it’s very moderate.

Thanks everyone,

That’s pretty creative. I would have never thought of that. Awesome.


My team (33) is using big LEDs to let the drivers know when something important just happened.

LEDs blue = ball possessed

LEDs green = lined up with a goal

LEDs red = latched onto tower and ready to hang

The last two were not functional at Kettering but will be at Troy:)

I think LEDs are the way to go because you can use them for multible functions. Although it does alert the other teams to our current scoring abillty:rolleyes: … Oh well well be getting hit anyway:p

We have one of these buzzers mounted in the center of our DS
It turns on whenever we have a ball in our possession. As a driver, I can say that it is tremendously helpful and has definitely improved our performance. Panel indicators and LEDs aren’t nearly as good because they require the driver to look at something other than the robot, or at least interpret slightly more visual data. I think that its quite a stretch to suggest that an intermittent buzzer of reasonable volume is going to bother your team mates in the middle of a supercharged match with music blaring and people cheering all around them.

Edit: I’m going to go ahead and recommend that specific buzzer from radioshack. Even though ours is just something someone happened to have, it looks just like that. It draws 15ma on 3.3 Volts, so you’ll have to use one of the high current digital outputs. Hook the negative wire from the buzzer to the digital out so that a logic low turns it on-- the outputs can sink more current than they can source.

Sorry if I wasn’t clear

The big LEDs are on the robot and very visible.

BJC, they are automotive cold-cathodes. They are also very large, 12" long tubes, compared to LED’s. We are powering them via Spikes on a dedicated 12v 20amp breaker, so no 3.3v DIO’s here.

Inspectors cannot allow air horns, sirens and other audio devices on the robot with sufficient sound level to create a distraction or hindrance that can affect the outcome of a match per: <R02.B>. Right now, there’s no inspection item for similar devices on the operator’s console. Do you wonder why there are so many rules?? :stuck_out_tongue:

Some students find it funny when, during inspection, I ask them if their robot has any lasers, flammable, flame sources, or toxic gasses. Frequently, I hear some “out-of-the-box” concepts involving flamethrowers, etc. All in good fun, of course.

As David has pointed out there is no rule against a noise source in the DS, however, do you really want to risk distracting your alliance partners?

Team 78 uses something very similar, we’ve used modified logitech dualshock 2 controllers for the last two years. The logitech dualshock two controller is the same model as the standard controller provded with the FTC kit of parts…only with a rumble feature. Last year we simply rewired the motors that controlled the vibrate inside the controller directly to the digital output of the DS and controlled it accordingly, but this year it required the cypress board to achieve the same effect.

By using the can bus on our jaguars we can monitor the current our vaccum is drawing and trigger the vibration motors when the current drops (when we have a ball in our possession). As a driver its particularly helpful when going for the balls that are against the bump nearest to me, which I can barely see.

Driver should be looking at the robot, so we put a light on the robot, activated by a vacuum switch on our ball sucker.

Vacuum switch is fairly inexpensive, and commonly used on high efficiency home furnaces.

With a 102db buzzer, I should think that your biggest problem would be your alliance partners beating you with their control stations.