Electronic Puzzle Box Uses Only Discrete Components

Puzzle box

Do you need an idea for a fun do it yourself gift for a friend or significant other? Look no further, [conductance] has you covered. He put together an awesome electronic puzzle box using all analog electronics. The puzzle case is shaped like an over sized die and is made out of wood. It also requires a small jumper cable and an external magnet to complete the puzzle.

This is a six-sided die, where each side has something different to offer. The “five” side of the die shows the progress you’ve made in completing the puzzle. Each of the five dots contains a green LED that will light up when the corresponding puzzle has been successfully completed.

The “one” side is completed by placing the included magnet over the dot. The magnet activates a reed switch which lights up the first LED. The “two” side contains a tilt switch. In order to solve this piece of the puzzle you must ensure the two side is facing up, as if you rolled a two. The “three” side contains three key switches. Each switch must be turned to a particular orientation. Once all three keys are configured properly, a third LED lights up.

The “four” side contains four sockets that fit the included jumper cable. This puzzle is solved by jumping the two correct sockets together. Finally, the number “six” side just has six momentary push buttons. All six buttons must be pressed simultaneously in order to light up the final LED. The tricky part is pressing all six buttons while simultaneously “rolling” a two in order to ensure the tilt switch is also activated.

Once all five LED’s are lit up, a relay is triggered which then activates a solenoid. The solenoid unlocks the door and reveals the prize. It’s always great to see electronics circuits like this that use all discrete components. This could have been accomplished any number of ways, but there’s something satisfying about a simple circuit that’s just right for the job. Be sure to check out [conductance's] schematic if you want to see how this puzzle works.

[via Reddit]


  1. You’re not fooling me. I’ve seen Hellraiser and know what happens when I open the box.

  2. Morgen says:

    The prize is an arduino. :-)

  3. Morgan Freeman says:

    What’s in the booooooooox???

  4. CNK says:

    “electronic puzzle box using all analog electronics”.

    Hmm… to create a digital AND gate. Best to just stick with saying discrete components before someone claims a 7400 chip to be analogue.

    Nice project though. Would be good for teaching digital fundamentals to beginners.

    • There is no such thing as digital. Digital is just an abstraction of analog with really fast rise and fall times, quantized voltages, and documentation that reinforces the abstraction. It’s fun to take people who have a computer science background and sit them in front of an oscilloscope, probing around and showing them that the rectangles and trapezoids of digital waveforms in data sheets are a lie. Zoom in, and you see the analog world that is just waiting to screw with you; things like signal reflections and inducting signals on parallel traces and an assortment of weird capacitive and inductive effects.

      • CNK says:

        But if a diferentiation is made it needs to be defined, if only for easier reference. Otherwise the next post with the “analog” tag might as well use an Arduino.

        Digital exists as a concept applied to analogue electronics. To begin looking at a 7400 chip by analysing the internal transistor functions is to rather miss the point – first it should be viewed from a digital perspective, then it’s analogue workings considered where necessary.

  5. scorinth says:

    Now we just need one with discreet components. :D

  6. Hirudinea says:

    Looks like fun, wheres my hammer?

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