Although you can find versions of these Electronic Monte boxes for sale on magic websites, I could not find one large enough for my needs nor one that included a buzzer (not just a light). So I built my own. In spite of the fact that my electronic knowledge only involves the ability to insert a plug into an outlet, I built my own the first time in under an hour for around $20.
The premise is simple. From among multiple buttons, you win if you can find the button that lights the light and sets off the buzzer. With the diagram included in my instructions you aren't limited to only three buttons either.
Since that first box, I've built the wiring into a display board (bulletin board) for a trade show routine that became a standard of mine for two decades.
In this document, I give you the simple wiring diagram, parts and part numbers to purchase from Radio Shack's website, and the routining for allowing the spectator to win or causing them to lose. In addition, I've included my approach for using a spectator's borrowed watch and/or the magician's own watch in a "no sting" version of the classic Bank Night premise.
1st edition 2018, PDF 4 pages
word count: 1488 which is equivalent to 5 standard pages of text