This is an upgraded version of a project originally by a fella who goes by the name pighixxx. He has some cool stuff around his website, check it out at http://www.pighixxx.net.
The ZEN BLASTER is a device that exists to annoy. It generates a random number of beeps at random time intervals at random frequencies. Throwing your echolocation for a spin as you try to find this little device that one of your former friends has placed in your office space.
The schematic for this circuit can be seen below (This image was created in KiCAD).


As you can see, not much to it! It consists of a small 8-ohm speaker a small amplifier circuit and a microcontroller to feed it random numbers. The microcontroller used was a Texas Instruments M430G2553 due to its low power consumption while in standby mode. Sure, would hate for this to run out of batteries before it can wreak havoc. Other than that, the other components are basic off the shelf electronic parts. A generic NPN transistor, some resistors, a few capacitors, a switch and a battery.


Off to the side I have a prototype that was made using an Arduino Uno, making sure the circuit works as designed before I go and start soldering.

Once the prototype proved the circuit worked I went ahead and started putting one and two together. Assembling the more refined prototype on some perfboard. The code is very simple, just a couple for loops controller by random numbers. It is available on my Github if you are interested. I think the final product came out pretty good! It is tiny, which make it concealable and easy to hide. No PCB for this, that would make it even smaller though. Maybe one day if there is a demand for some mass produced random buzzers.


Here's the Bill Of Materials for this project

BOM Item # Item Name Quantity Price/Unit Total Cost
1 MSP430G2553 1 $2.69
2 8Ω Speaker 1 $1.00
3 SPDT Board Switch 1 $1.00
4 2N2222 NPN Transistor 1 $0.25
5 100Ω Resistor 2 $0.05
6 1kΩ Resistor 1 $0.05
7 4.7kΩ Resistor 1 $0.05
8 22kΩ Resistor 1 $0.05
9 100kΩ Resistor 1 $0.05
10 10µF Capacitor 2 $0.05
11 100µF Capacitor 1 $0.05

This article was last edited: November 2017