Help with Electronics

Discussion in 'The Projects Forum' started by NeuroV, Aug 9, 2011.

  1. NeuroV

    Thread Starter New Member

    Aug 9, 2011
    10
    0
    Hi everyone,

    This is my very first DIY project and I really think it's something I'll be able to accomplish but with your help.

    I'm trying to pick out the proper electronics to purchase based on the schematics.

    Could you guys tell me if my list of electronics I will be purchasing from the electronics store are accurate?

    So, firstly, here's the schematic: http://www.diyguitarist.com/Images/EbowSchematic.gif

    I'm wanting to build the ebow guitar effect for fun.

    Parts:

    1) Solderless breadboard for trial
    2) Input and output coils - for the input I'm getting a 50 Ohm sensor and output an 8 Ohm driver. I'm going to use magnetic buzzers for this.
    3) 2 capacitors both 10 mF
    4) 1 diode (1N4002)
    5) 47 n capacitor
    6) Now, I can't tell if I need 3 resistors or just the 1. Because from my reading it seems that the symbol near the input and output symbols look like resistors too. If it's just 1 resistor is it 10 ohms?
    7) 220 mf 16V capacitor
    8) 9V Battery
    9) LM386-6 amp

    Thanks
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    [​IMG]

    Parts list as follows:

    1 LM386 IC
    1 Dynamic Microphone (can be a speaker)
    1 Speaker
    2 10µF capacitors (marked incorrectly as mF)
    1 220µF capacitor
    1 47nF capacitor
    1 diode, 1N4001
    1 10Ω resistor

    Basically whoever drew the schematic wasn't very good.

    Don't try to use an electret or condenser microphone, they won't work. That is why I suggested using a speaker as a microphone. It will work, though not the highest fidelity.
    .
     
    Last edited: Aug 9, 2011
  3. #12

    Expert

    Nov 30, 2010
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    Those mf's are supposed to be uf's...microfarads.
    The capacitors should be rated at 10 volts or 16 volts, and 16 is better.
    The output section has 47 nanofarads in series with 10 ohms...to ground, and a 220uf cap to the output device, The output device is apparently your 8 ohm buzzer.

    It would be good to put a very small fuse in the battery line before the 1N4002 diode so the fuse blows instead of the battery burning up if you connect it backwards. I don't think you can buy fuses less than a tenth of an amp, but try. This circuit should work with a 50 milliamp fuse.
     
  4. Wendy

    Moderator

    Mar 24, 2008
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    I prefer to put the diode in series, so it doesn't conduct if connected backwards.
     
  5. #12

    Expert

    Nov 30, 2010
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    I was worried about losing too much voltage. That's why I recommended a fuse. If the circuit is happy with the diode in series, that is a good way to do this job.
     
  6. JingleJoe

    Member

    Jul 23, 2011
    185
    10
    Should be fine with a diode to protect the circuit from backwards battery connection, having used very very very similar circuits to this one before, I know they work from lower voltages.
     
  7. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Of course our dear friend Bob Pease has already been here with an excellent idea for reverse input protection with minimal voltage drop:

    [​IMG]

    From "Troubleshooting Analog Circuits," page 164. Amazingly this entire book is available online. Geesh, and to think I actually paid good money for my copy!
     
  8. gerty

    AAC Fanatic!

    Aug 30, 2007
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    Link doesn't work.
     
  9. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Apparently that website is on a banned list here, any attempt to even directly type the site name outside of url tags produces "********"

    Thus I will not attempt to bypass that security as this may be a popular copyright bypass sight.
     
  10. Veracohr

    Well-Known Member

    Jan 3, 2011
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    Given that this is an Ebow, I'm pretty sure the input and output components are supposed to just be coils, not specifically microphone and speaker. The input and output are magnetic fields, not audio.

    Explanation from the same site: http://www.diyguitarist.com/DIYStompboxes/EbowTech.htm
     
  11. Wendy

    Moderator

    Mar 24, 2008
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    I'm not sure what an Ebow is, but I know something about electronics. It is basically a modified audio circuit, so I extrapolated. The rest of the schematic is pretty astandard, mf = millifarads, you can use u or µ for micro. Most electrolytic capacitors have polarity clearly marked (because they will spew their guts if connected backwards), etc, etc.

    Reading a little deeper, the input coil is specifically a telephone pickup, which can be bought from several different sides. I don't know if a telephone coil will work for the output, they mention a transformer.

    BTW, a speaker uses a magnetic field to reproduce the sound. It too is fundimentally a coil.
     
  12. Veracohr

    Well-Known Member

    Jan 3, 2011
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    It's a guitar-playing accessory, short for "electronic bow" (like a violin bow). It causes a vibrating string to continue vibrating after it should have naturally quieted.

    You're right about the pickup and transformer, I missed seeing that.
     
  13. Audioguru

    New Member

    Dec 20, 2007
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    The coil in a buzzer WILL NOT WORK!
    The coils need a magnetic core as was explained in the project.
     
  14. NeuroV

    Thread Starter New Member

    Aug 9, 2011
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    Hi guys, thanks for everyone's input. I ordered most of the parts from digikey and received all except exactly what this discussion has been revolving around so far. The input and output parts. I'm stuck now. Someone recommended EMX-2T01 Transducer with 50 ohm and 8 ohm coil resistance. But, after contacting the manufacturer they said the turn around wait to get these parts could be about 2 weeks to a month.

    Radioshack or Fry's don't carry the transducers. And I also called local shops too. So, do you know if there any alternatives? Bill, you mentioned telephone pickup. I read on a youtube video of someone mentioning motherboard speakers.

    http://www.youtube.com/watch?v=UkQhRFS6sRM - Here's the video of someone using the buzzer and chopping off the cap to get access to the coils.
     
    Last edited: Aug 15, 2011
  15. Wendy

    Moderator

    Mar 24, 2008
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    Still needing help?
     
  16. SgtWookie

    Expert

    Jul 17, 2007
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  17. Audioguru

    New Member

    Dec 20, 2007
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    They should not call the coil, magnet and diaphragm a "buzzer" because it is a transducer. A buzzer has a built-in oscillator that these transducers do not have.
     
  18. NeuroV

    Thread Starter New Member

    Aug 9, 2011
    10
    0
    Yes please.

    Okay, so I finally built the prototype. Here are my concerns. Before I plug in the battery I want to make sure that all the connections are right. Below are several pictures of what I've assembled. I have one final concern. How would I connect the diode?

    Alligator Clip Config on the Buzzers:

    8 Ohm
    Yellow = "+"
    White = "-"

    40 ohm
    Black = "+"
    Red = "-"

    Link to Schematic:
    http://forum.allaboutcircuits.com/showpost.php?p=388208&postcount=2

    My assembly:

    Overhead view with Labels:
    http://i52.tinypic.com/24zwxar.jpg


    Closeups:
    http://img824.imageshack.us/img824/5386/img0046vm.jpg
    http://img835.imageshack.us/img835/8973/img0047oz.jpg
    http://img62.imageshack.us/img62/6060/img0048si.jpg
     
  19. Wendy

    Moderator

    Mar 24, 2008
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    I see where your power comes in, but how does it get to the other side of the board?
     
  20. NeuroV

    Thread Starter New Member

    Aug 9, 2011
    10
    0
    Hi Bill!

    Thank you. I actually realized that I was missing the connection to the other side so I connected a jumper wire from the negative end of the right side of the bus strip to the negative end of the left hand bus strip.

    The other issue is that I'm getting sound from the 8 ohm speakers.

    I was hoping that both buzzers would be quiet until I made vibrating sound.

    Thanks
     
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