5 Responses to PC to arduino to toy crane

1. Don says:

   February 22, 2011 at 10:45 pm

   Thanks for posting the video.

   What transistors did you use? And the max motor current?

   Reply
2. engineerzero says:

   February 23, 2011 at 12:07 am

   I used NPN low-power transistors 2N222A, 2N3904, and 2N4401s from Radio Shack. They come in a pack of fifteen, five of each kind. Surprisingly cheap.

   According to the specs on the back of the package, the lowest collector current is for the 2N3904 and is 200 mA. I checked just now and the only 2N3904 in the circuit was the transistor feeding power into the motor when pin 13 was high. So the motor current would have to be less than 200 mA.

   Reply
3. engineerzero says:

   February 23, 2011 at 12:17 am

   BTW, out of respect for the Arduino pins, in hindsight I would have ‘fine-tuned’ a lower resistance rather than leaping down to one-fifth the value. But 220 ohm resistors were what I had available.

   Just now I checked the arduino.cc site and it says the max current draw on a pin is 40mA. At five volts, that works out to a 125 ohm minimum. So I guess I’m safe.

   Reply
4. Don says:

   February 23, 2011 at 7:16 pm

   Kinda wondered what those transistors were. explains it. Plus those half-installed examples were enlightening.

   Reply
5. Don says:

   February 23, 2011 at 7:36 pm

   Goofed up the link before. Trying again:

   Kinda wondered what those transistors were. explains it. Plus those half-installed examples were enlightening.

   Reply

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