Wednesday, June 27, 2018

Spite speakers!

This is actually an ultra sonic speaker. What the hell does that mean you ask?

Well.. since you asked. It basically provides directional sound. The sweet spot was very narrow which I was actually pretty impressed by.

There is an real market for these things. Like museums so you don't get sound bleeding out into parts of the museum you don't want it to be in. But, when they get cheap enough I'm going to buy one to keep my neighbors in check.

The only reason I didn't set up my sound bar to start playing my neighbors dog back to them on 11 was because it would piss off the other neighbors. With directional sound.......... the problem neighbors get all the love, and the others don't become mad. Maybe I'd even turn it up so they got the brown noise. I don't know. Depends on how many months their dog wakes me up.


  1. Capital of Texas RefugeeWednesday, June 27, 2018 2:57:00 PM

    You could DIY that if you have some patience and some circuit board design skills ...

    Those drivers look a lot like directional piezo PC board speakers, probably a 12V version, but with little plastic shrouds that help keep the signal mostly uni-directional. One of them isn't very powerful on its own, but the 84 of them in a 14x6 grid that are on this board would be powerful enough for lower volume museum PA systems.

    See if you can find a cheap supplier of 12V PCB speakers in 100+ bulk that don't have control boards on them for buzzers if you really want to go that route.

    A better bet might be some "detuned" insect repellent transducers -- in a pinch, you can install Spectroid for Android on your phone and use it as an ad hoc audio spectrum analyzer during the "detuning" process.

    By "detuning", I'm referring to where you remove a certain fixed resistor from what is likely to be an RC tuning element for something like a bipolar 555 timer or an LM741 op-amp so you can augment it with a decent tolerance (1% or 2%) trim pot with a big adjustment screw or wheel.

    Or if you'd like to try this on your own, this is a start but with a few problems: 555 tone generator. If you're going to use that as a guide, I suggest using a 6V lantern battery and modifying the left diagram so the 330 ohm resistor is actually a 270 ohm resistor plus a 330 ohm trim potentiometer in series that you can adjust with a screwdriver. A TIP31A/TIP31B power transistor would also probably do the job instead of the sometimes hard to find 2N3053 transistor.

    That will let you adjust the volume to low but infuriating levels.

    Here's another "electronic mosquito repellent" example shown on a prototyping board. Ad hoc prep of a circuit board after the prototype should be easy enough -- there are copper clad prototyping boards that resemble the plug board in this example, and you can just solder to them and plate the remaining unused connections with more solder in a pinch. (This article does a better job of explaining the 555 timer frequency calculations as well.)

    The "buzzer" in this last example is what I'm talking about -- it's a "piezo" buzzer without a sound control board stuck to it.

    This should even keep Tard Cat away -- I've used this trick to keep dogs from wanting to do their nasty business anywhere near my door ...

    You really don't want to know about my "rat trap", BTW. :-)

  2. Capital of Texas RefugeeWednesday, June 27, 2018 3:04:00 PM

    Oh, yeah, did I mention that NEC/Renesas makes these chips? :-)

  3. Yeah. Double E stuff is not my strength. I'm not sure I have the patience. But I'm sure with the right motivation I could be talked into it some day.

    Your not drowning those rats are you? Seems like that is a popular way these days. People fill a bucket with water and then put vermiculite in which floats making the rats think it's stable soil. Then a little food on top and a little rat diving board. I mean ramp. It's all over youtube.

  4. Capital of Texas RefugeeFriday, June 29, 2018 6:54:00 PM

    The solution is humane, yet shocking ...

    What kind of EE do you take me for??? :-)