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Author Topic: NPN/PNP Transistor  (Read 542 times)
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I have 2 C945 transistors and 2 BR9014 transistors that I would like to use for a h bridge. I've been trying all day unsuccessfully. When I do a basic circuit like that:,52984.0.html, and use a C945 alone, it does work accordingly to my script, the motor spins for one second, stops, and does it over and over again. But with a BR9014, it just keeps spinning forever, without stopping. How's that? I really don't understand and have been trying all day.
I first tried the H bridge, then I tested all the transistors I had, checked each one of them to know if they were NPN or PNP. I finally selected these 4. I'm just wondering if it's normal that it keeps spinning with the BR9014... But I've already tried the H bridge and it doesn't work anyway.

What am I doing wrong?

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By C945 do you mean 2SC945?  Often japanese numbered transistors (2SA, 2SB, 2SC, 2SD, 2SJ, 3SK etc)
are marked with the "2S" implicit.  "2" means "3 leads", "S" means "silicon".

The 2SC945 only good to 100mA max so isn't really up to powering a motor.  And its NPN.

[ BTW which motor are you using?  What current does it take - if much above 100mA you risk
blowing the transistor ]

BR9014 doesn't seem to exist... Perhaps you mean 9014?  There are several manufacturers
with a 9014 numbered NPN transistor, again 100mA.

What pin out are you assuming for each transistor - check against datasheets for 2SC945 and

[ and please don't cross-post or multiply-post - you already have a thread about these issues, its
far less work for everyone to keep to one thread if its about the same circuitry ]
« Last Edit: June 28, 2013, 11:20:07 am by MarkT » Logged

[ I won't respond to messages, use the forum please ]

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You've got to stop making multiple threads and focus more on the issue.

You have a Motor (to us, unknown current requirement).
You want to drive it forward / reverse from an arduino.

A properly selected / designed H-Bridge is what you need.
To do that you'll need to know how much stall current your motor draws.
Select a H-Bridge or Transistors greater than that current, and supply it from a suitable supply (not the arduino 5V pin).

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