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  • Author Author: tariq.ahmad
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Electronic Dice Kit -- The Learning Circuit 49

 

 

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

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  • 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 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!

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  • 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!

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