Kid Friendly 8 to 12 LED binary "counter like" circuit assembly?

Discussion in 'General Electronics Chat' started by thatoneguy, Nov 25, 2010.

  1. thatoneguy

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    Feb 19, 2009
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    My turn to ask a question. :D

    At the local science center,there is a demo of "installing a circuit". When both big knobs are screwed all the way down on a PC Board, power is applied and the circuit, essentially a ripple counter with 12 LEDs starts. It uses a CD4040 clocked by a 7404 in oscillator mode.

    The neighbors' kid wants to make one that "Does the same thing".

    The problem with this: Roughly 2 hour time constraint to build (keep kid busy for a "movie length period"). I'm in a tossup between breadboard and etching a PCB for this, but I think a pre-made PCB would take away the learning, so soldering on perfboard might be the best "learning" thing.

    I could set up a PIC to simply do a ripple count across the ports, but I don't think anything would be learned that way without him understanding code (he's only worked with the Radio Shack 150 in one set). It may be how it ends up though.

    The LEDs do not need to be very bright, so I am down to two ideas that would fit the time constraint. The biggest issue is parts on hand and assembly time. I'm leaning mostly to a CD4060, which will light the LEDs dimly (same as the science center), but work without extra support ICs due to the internal oscillator. The other option is a pre-programmed PIC. If somebody else has ideas, shout them out!

    I have a few of the most of the common buffer and mux logic ICs, but I'm fairly sure whatever is suggested I won't have, I have a few 4060s and 4017s (I don't think he'd like the "look" of the 4017 output).

    So the question is: What is your guys opinions on the most educational and "kid friendly" solution to this problem? Solderless breadboard, PC Board, or stripboard, and how many devices on said platform. If I do a PC board, I'd like to have him "help", but that could get messy...

    --ETA: He is 9 years old
     
    Last edited: Nov 25, 2010
  2. Artikbot

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    Nov 7, 2010
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    How old is he?

    I think a solderless breadboard can be good if he just wants to see it.

    In case he's wanting to keep it (what would be kind of obvious) I'd say do it on a stripboard, that way he'll also get a base on prototyping on solderless breadboards.
     
  3. thatoneguy

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    I forgot that part. He is 9 and is fairly handy with his hands, I've helped him with some problems on the Radio Shack experiment box and he could count the grid numbers and connects stuff as fast as I'd expect with a few errors.

    I'm leaning heavily towards proto board so he can keep it around.
     
  4. bertus

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    Hello,

    I started with electronics with the EE kits from philips:
    http://ee.old.no/

    It used springs to connect the parts.
    On the library pages there are some manuals:
    http://ee.old.no/library/

    You could "translate" the circuits to a breadboard (those did not exist back then).

    Bertus
     
  5. Wendy

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    Solderless breadboard if he is focused, if he shows focus and skill then a PCB. If not then make it out of modules he can assemble. Maybe a mix of PCB and protoboard.
     
  6. SgtWookie

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    Jul 17, 2007
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    Consider getting one of these for him:
    http://www.radioshack.com/product/index.jsp?productId=3814337

    The board and lab manuals were designed/written by Forrest Mims III, a noteworthy citizen/scientist.

    Radio Shack's website is starting to carry his "Engineers' Mini-Notebooks" again after dropping them from the inventory years ago.
    Volume I: http://www.radioshack.com/product/index.jsp?productId=10852489
    Volume IV: http://www.radioshack.com/product/index.jsp?productId=10852492

    They also have started to carry Volumes II and III again. Volumes I and IV are the "must have" books, as even though fairly small, they are jam-packed with useful information.
     
  7. thatoneguy

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    Attached is what I've put onto a breadboard, and it runs with 4 AA batteries. I have a 10 Segment LED bar scavenged from something, so I used one for a power light, and doubled up on the slowest outputs. The first few cycle so fast it is pointless in simulation, real life they still flicker too quick, and not much I can do with the oscillator speed, it isn't quite "reliable", since I don't have a 74HC14 handy.

    [​IMG]
     
  8. Wendy

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    You want me to draw a layout?
     
  9. thatoneguy

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    If you want. That is the best I can do for low parts count, 4 IC sized packages, 1 resistor, 1 cap. The rest is wires.

    I have resistor modules of various values, and another "bar graph" 10 LED strip. Was trying for minimum parts/medium wiring, reliability isn't the greatest, nor brightness. Thinking of adding a couple BJT ICs to up the current, but then I'm out of solderless breadboard space.
     
  10. retched

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    I dont see decoupling caps! ;)

    (joke)
     
  11. thatoneguy

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    Actually, that's a good point.
    I put 3 0.1uF down each edge of the solderless breadboard, spaced evenly, 1 at each edge and one in the middle, for a total of 6. It has made things work that I had a lot of issues with before essentially using the shotgun approach.
     
  12. retched

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    And that is a good idea.

    Consider adding that to your decoupling sticky.
     
  13. Wendy

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    Which breadboard, I could fit more in I think. I've had a lot of practice. I'll need the resistors footprint to draw it.

    [​IMG]

    [​IMG]

    I kinda assume the second since you mention running out of space.
     
  14. thatoneguy

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    Yeah, I have 2 of the short ones, connected together on the long edge to make a square, just in case I need more room (only using one now). There are 0.1uF caps on the power rails at positions 2, 15, and 30 on each side of both boards, power input is on row 1.

    I have long solderless boards as well, but I think I'm going to make one reliable, the current one is hit and miss, also running in MHz range, need to power cycle it to get the oscillation going, can't believe I don't have a 74HCT14 laying around here. :eek:

    Once that is done (stability), I think I'll make a PCB for it, so the project will be "Here's what it does, now we transfer it to a PC Board" Would that be interesting for a kid?

    Resistors are 1/8th watt, the 470 ohm IC is just that (16 pin DIP), as shown in the schematic above, the case is white though, but that's no big deal.


    --ETA: I guess instead of trying for the inverter clock, you could do one up with the minimum parts 555 timer for about a 2kHz clock. I know you are thinking it, saves space, something you know, and everything! But the actual doesn't matter as long as I can explain it to be interesting to a 9 year old. That's the important part of this thread. I guess I'll grab him the notebooks at RS too for an early Christmas gift.
     
    Last edited: Nov 26, 2010
  15. Wendy

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    I see what you mean about room. You can either use a long board, or use a second short board for the clock. The clock itself can be a source of some amusement though, since (while you didn't show it) it can have a blinky light of its own that can be selected between fast and slow.

    Here is the preliminary layout I was playing with.

    [​IMG]

    Since you are going to have a cluster of wires between the counter and the resistor, and the resistor and the LED, a longer board might be better. It is easier to illustrate crossovers between sides that way.

    I'll go with whatever you select, clock schematic included. Something you might point out, though it may be too early for him, is people like NASA used these as is for things like frequency counters.
     
  16. thatoneguy

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    I'm putting the LED on the second board now, so wires labeled "to LED 1" would work. I may just use male-female header jumper wires to connect the LED in the end pror to the PCB.
     
  17. MMcLaren

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    I would be happy to donate a design if you're interested. It's just a more up-to-date version of something I used to let my nephews and nieces build many years ago when they were little.

    Let me know... Happy Holidays everyone!

    Cheerful regards, Mike McLaren, K8LH
     
  18. thatoneguy

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    That's a pretty cool project! I'd be interested in it for the "next time" I need to watch a kid.

    Does anybody know of a book or web based "PICs for Kids" or similar?

    I'd like him to understand what he is making, but maybe that is aiming high for a 9 year old.

    I'm currently in a tossup between using a 12F683 or a 555 for the clock supply on the project above. Then it might all fit on one board.

    For giggles, I added some "antennas" so it only oscillates if you move your hand near the jumper wires sticking up (connected to the in lines on the 7404). It's kind of neat for a proximity detector, I guess.
     
  19. bertus

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    Hello,

    Did you think of a "theremin"?
    That is a music instrument that can be played by waving hands.
    Here is a pic of a tone generator used in the "theremin":

    [​IMG]

    This picture is a link from this page:
    http://www.thereminworld.com/schematics.asp

    Bertus
     
  20. thatoneguy

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