Need some ideas, please :)

Discussion in 'The Projects Forum' started by RayInMS, Apr 8, 2013.

  1. RayInMS

    Thread Starter Member

    Dec 12, 2012
    89
    1
    I really enjoy making simple circuits and boxing them up as toys for my son. I'm an amateur radio operator, and he likes to "play radio" with the stuff I have made. So far, I've built a couple of 555 oscillators, including the toy organ circuit (that's his favorite), and other doo-dads with LEDs and switch matrices.

    I want to do something new for him, but I've had trouble deciding on my next project. I'm leaning toward something along the lines of a voice changer (or something similar). I've seen a couple of voice changer schematics online, but I've had some rotten luck in the past with randomly selected circuits off the internet, so I'm not going that route this time.

    I'm limited to +9V (or below) power options (e.g., nothing requiring dual supply voltages) and I'd like to stick to basic components (e.g., nothing requiring special ICs).

    Any suggestions?

    ETA: I'm not stuck on a voice changer. Other ideas are welcome, too. :)
     
    Last edited: Apr 8, 2013
  2. Brownout

    Well-Known Member

    Jan 10, 2012
    2,375
    998
  3. hexreader

    Active Member

    Apr 16, 2011
    250
    82
    My niece and nephew used to love hunting for coins hidden under a rug. It was corny, but it kept them both amused for hours. That was about 30 years ago!

    I had built a very simple metal detector with just a tone as output and a multi-turn coil of wire for a detector.

    No idea what the circuit was, but it was simple and I am guessing that you will find many circuits on the net. Start with the simplest circuit - just an oscillator with the coil as frequency tuning device, and small speaker to indicate frequency.
     
  4. RayInMS

    Thread Starter Member

    Dec 12, 2012
    89
    1
    Was the coil air wound or iron (toroid)?
     
  5. patricktoday

    Member

    Feb 12, 2013
    157
    42
    It would be difficult to get really cool voice effects without using digital signal processing ICs. A voice tremolo circuit could be an idea with a 555 timer which switches the voice on and off rapidly at some adjustable rate.
     
  6. elec_mech

    Senior Member

    Nov 12, 2008
    1,513
    193
    I made my three-year-old a what I call control console and incorporated several smaller circuits. It has the following:
    • A large red lighted button that plays up to 20 different sounds when pressed. I used audio clips from Looney Toons, e.g., "What's Up Doc?", "You're Despicable", "I Tawt I Tawt a Puddy Cat", etc. Used a sound module from here.
    • Three 10-segment blue LED bar graphs placed in a row that light up as a sliding pot is pushed upward.
    • A current meter that turns with a knob attached to a pot. I made a label to put behind the needle that has the speed designations from Space Balls: Light Speed, Ridiculous Speed, Ludicrous Speed, and Plaid.
    • Eight arcade buttons attached to an eight sound keychain. Has a machine gun, lazer gun, and bomb drop among others.
    • Four toggle switches each attached to 10mm diffused LEDs; red, yellow, green, & blue. Fifth switch attached to a 5mm RGB LED that changes color on its own.
    • Large toggle button with a missile control-like cover for turning the entire circuit on and off.
    Below is picture of the prototype - I still haven't taken a picture of the finished console. At some point I plan to post this to the finished projects forum on AAC.

    MAKE magazine had a similar project with a world map.

    These are just some ideas. I like the toy organ project, I may have to do that next.
     
  7. hexreader

    Active Member

    Apr 16, 2011
    250
    82
    Just a salvaged AC motor coil about 2 inches square and a hundred or more turns with no core.
     
  8. RayInMS

    Thread Starter Member

    Dec 12, 2012
    89
    1
    I found a metal detector circuit that uses a 555 timer and other basic components. The only problem is that it also requires a 10mH inductor. The schematic indicates it should have an iron or ferrite core (toroidal, maybe?). I can't post the schematic right now (at work, stupid filters), but based on the collective knowledge here...can you guys take a guess at the following:

    1. Can I make the coil myself? Or should I just try to find one?
    2. If I can make one, any suggestions as to how I should go about it? I don't fool with inductance much.
     
  9. RayInMS

    Thread Starter Member

    Dec 12, 2012
    89
    1
    Well, in the process for searching for new ideas...I discovered that I need to build a new piece of test equipment before I do anything else.

    I was playing around with transistors tonight, and some of them seemed to crap out or act funny on the breadboard. So, I did the logical thing and played Google Warrior...I looked for "transistor tester" circuits and found a few. But things didn't work out like I thought.

    Testing results:

    NPN transistors with CBE pins correctly aligned + switch ON = LED lit
    NPN transistors with CBE pins correctly aligned + switch OFF = LED not lit

    Good. Right? Yeah...

    NPN transistors with C/E pins reversed + switch OFF = LED lit
    NPN transistors with C/E pins reversed + switch ON = LED lit

    I didn't even get to testing PNPs. I got too frustrated.

    Link to schematic is here (World's Simplest Circuit).

    Transistors used were RatShack specials (2n2222a and 2n3904).

    What's going on? Is there another transistor tester circuit that I can build?
     
  10. Brownout

    Well-Known Member

    Jan 10, 2012
    2,375
    998
    I don't think you should be reversing the pins.
     
  11. edwardholmes91

    Member

    Feb 25, 2013
    186
    19
    Sorry for sort of hi-jack your thread... but would you mind posting a copy of the schematic for the toy organ? I'm working on one at the moment, you might of seen my thread?
     
  12. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,871
    1,394
    Ray,

    Google "crackle box" and see if you think your boy would have fun with it.
     
    elec_mech likes this.
  13. RayInMS

    Thread Starter Member

    Dec 12, 2012
    89
    1
    I built it to test transistors...as in "hey, is this pinout right?"...I used a diode in front of the base to prevent funky stuff from happening. Is there a better way?
     
  14. Brownout

    Well-Known Member

    Jan 10, 2012
    2,375
    998
    Yes. Know what you're testing and insert it correctly. Who knows what happens if you insert it backwards?

    If passed while inserted correctly, then I'd say the transistor is good, at least for the test you're running. There are certainly better tests.
     
  15. RayInMS

    Thread Starter Member

    Dec 12, 2012
    89
    1
    Can you elaborate?
     
  16. Brownout

    Well-Known Member

    Jan 10, 2012
    2,375
    998
    There are lots of parameters that can be tested, forward current gain, unity gain frequency, reverse breakdown voltage.... Look at some manafacture's data sheets and see all of the parameters being tested. Sometimes they even show the test circuits.
     
  17. RayInMS

    Thread Starter Member

    Dec 12, 2012
    89
    1
    Looks interesting! Thanks!
     
  18. RayInMS

    Thread Starter Member

    Dec 12, 2012
    89
    1
    OK, will do. Thanks.
     
  19. absf

    Senior Member

    Dec 29, 2010
    1,493
    373
    Here is a good transistor tester that I made few years ago and am still using it. It says that it can test transistor in-circuit but I have never used it for that purpose. It also include layout of components on vero boards.

    http://www.docstoc.com/docs/150898855/In-Circuit-Transistor-Tester

    Allen
     
Loading...