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Topic: Breadboarding question (Read 2 times) previous topic - next topic

Danrosey

Jan 11, 2011, 04:14 am Last Edit: Jan 11, 2011, 04:15 am by Danrosey Reason: 1
I've got a really beginner question that is giving me some trouble.  I'm following along with the Learning Tone (http://arduino.cc/en/Tutorial/Tone) example.  I've been able to successfully produce the tone example, but I am a bit confused with the breadboard layout.

The following three pictures help show what I am referring to:


The black wire you see going to the breadboard is the positive, while the black cable going to the GND is GND.  The left-most photo is the first setup I begin with--unsuccessful.  The middle photo was my second attempt--successful--positive, resistor, jumper stacked in same column.  And the right-most photo is my "just testing to see what happens" attempt--also successful--with the positive and jumper cable in same column, while the resistor is in the same position as the left-most image.

My question is: why didn't the first layout work?  From some of the basic examples with LEDs and pushbuttons, the resistor and jumper cable were oriented in this manner.  From what I can gather, the middle is obviously the correct layout, while the right-most is bypassing the resistor all together. Is that correct?  

CrossRoads

It appears to me that the middle also bypasses the resistor - you have both sides of the resistor connected together (confirm this with a multimeter).
What value resistor are you using?
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

retrolefty

Draw your circuit on paper first. And share that with us if it doesn't work. Trying to figure out your photos where wires leave and come into the photo makes a difficult task even harder.  ;)

Lefty

Danrosey

#3
Jan 11, 2011, 05:22 am Last Edit: Jan 11, 2011, 05:26 am by Danrosey Reason: 1
Quote
It appears to me that the middle also bypasses the resistor - you have both sides of the resistor connected together (confirm this with a multimeter).
What value resistor are you using?


I grabbed 100K ohm but I realize now I should be using 100 ohm. Is the first actually now correct but I simply used too large of a resistor?

Quote
Draw your circuit on paper first. And share that with us if it doesn't work. Trying to figure out your photos where wires leave and come into the photo makes a difficult task even harder.  


Is this more helpful?


Edit:  I think I answered my own question.  Popped in a 220ohm resistor and the sound was a bit muted but it worked properly with the "1st" layout.

CrossRoads

#4
Jan 11, 2011, 05:49 am Last Edit: Jan 11, 2011, 09:10 am by CrossRoads Reason: 1
Excellent work.
Are you trying to drive a speaker? It will be awfully quiet, you get at most 5V x 40mA = 200mW of power out. If you can connect to a powered speaker, like an amplified computer moniter speaker, the sound will be much more impressive.
Or you can build up your own amplifier, I have this circuit for my Arduino to drive with a Tone melody.

Is just a classic MOSFET AC amplifier, as found here: http://fourier.eng.hmc.edu/e84/lectures/ch4/node13.html

Only in this case, we are not worrying about trying to stay in any linear region, we are just letting the output swing peak to peak from the +12V supply ground.  I only have it warble from between C6 & A5 a few times, sounds nice thru a high power 2.5" speaker. Plenty loud :-)

Ignore the 2nd RL resistor, I was playing with switching 2 resistors to make a hi/lo volume control. 68 ohm/34 ohm does not make much difference.

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

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