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The Learning Circuit 49: Electronic Dice Kit

 

 

In the previous episode, Karen did an overview of integrated circuits or ICs. This week, Karen chose an electronics kit that contains two ICs, a phase locked loop, and a ripple binary counter. A phase locked loop takes one external input and one internal input, comparing the frequencies of their signal and turns that difference into a voltage that goes back to adjust the internal signal. This process continues until both external and internal signals are equal. This process generates an output signal that slowly changes then stabilizes. In today’s kit, an electronic dice kit, that signal from the phase locked loop IC is used as the clock input signal of the second IC, the binary counter.

 

The binary counter IC is a 7-stage ripple counter, with each stage generating a binary digit.

 

Once you understand how to count in binary, you can see that each digit is created as a square wave signal. In the end, the ripple counter IC outputs a signal that randomly flashes the 7 LEDs ending in a die roll of a typically 6-sided die.

 

Bill of Material:

 

Part

Hobby Project Kit, Electronic Dice, Single, Simulated Random Dice Roll

Velleman1Buy NowBuy Now
9V BatteryEnergizer1Buy NowBuy Now
Anonymous
  • in reply to shabaz

    So there will be some dimming of LEDs slightly depending on the dice value.

    You might find it messing up the randomness, too, if you did a statistical analysis. The changing of the supply voltage to the two chips, as the display changes, probably affects the timing of the RC oscillator on a cycle-by-cycle basis as well.

     

    On the other hand this circuit uses a lot less parts than the Velleman kit! That has a surprising amount of diodes in the video.

    It gives them the normal diagonal two or three symbol. Your teenage self cheated and had the two or three horizontally across the middle!

  • in reply to jc2048

    Hahaha. That's totally fine! I was so busy making sure I understand how the chips worked that I didn't even think to thoroughly investigate how they were connected to the rest of the circuit. Thanks for pointing that out actually. I'm always happy to see others explain anything I missed or left out or even made an error on. It's all about learning!

  • It's fun trying to think of ways to implement dice : )

    Here's my attempt (as a teenager), it was published in some magazine at a time of less scrutiny. IC1 is 40106, and IC2 is 4029.

    The LEDs are in this orientation:

    D3            D4

    D1    D7    D2

    D5            D6

     

    It's not a great circuit (one current limiting resistor across the entire circuit, to save on parts : )

    So there will be some dimming of LEDs slightly depending on the dice value.

    Also a less crude circuit would add decoupling capacitors across both ICs.

    On the other hand this circuit uses a lot less parts than the Velleman kit! That has a surprising amount of diodes in the video.

  • I'm sorry to have to say this, after all your hard work researching PLLs and explaining them to us, but from the circuit diagram it looks like the designer just used the VCO [voltage-controlled oscillator] part of the chip; it's not functioning as a loop. The VCO frequency is simply set by the voltage on C2. When you release the switch, the capacitor discharges and the frequency falls until it no longer oscillates and the counter then stops counting.

     

    An interesting question, for someone learning electronics, would be to ask them which numbers they would bet on coming up the most (if you puzzle out how the diodes and the transistor decode from the 3-bit counter [= 8 states] you'll find that two of the numbers come up twice, though they're displayed differently each time).

  • in reply to makerkaren

    HI Karen,

     

    What I find most useful are the voltage and current values plus the timing for the gate operations. Next would be logic tables followed by clock pulse edges.

    The voltage and current provides you with needed information about how stable your power needs to be and an indication about needing pull up resistors.

    The timing gets important when you get into synchronized logic. Gate delays can cause a lot of problems to the uninitiated.

     

    So I would start slow with the data sheets and introduce the information in stages. Your ten minute format is great, just long enough to get a point across, but not so long that you get bored.

    Break down the parts of the Data Sheet and just show little bits pertinent to the lesson of the day.

     

    DAB

  • in reply to DAB

    In the project episodes, if I pull information from the data sheet, I try to show it. There is a lot of information on a data sheet and it obviously varies depending on the component, or even type of IC. Much of that information is useful for more advanced electronics projects. The goal of TLC is to focus more on the basics for those just getting started. In that case, with the information being intended for those new to using ICs, what portions of an IC data sheet do you think are the most important to cover, and that can be covered in the limited time of a 10 minute video?

  • Good episode.

     

    You did a very good job of explaining how the IC's worked and how binary looks compared to decimal.

     

    I think you should try to go over an IC data sheet and explain how it describes what goes on inside an IC and how it provides the necessary information to properly use each IC in the proper conditions.

     

    Well done.

     

    DAB