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Topic: PNP transistors... how to use them? (Read 4481 times) previous topic - next topic

eddiea6987

motors is 9-18v thats about all its said in the little radioshack bag. transistor is TIP42G
I could print the Arduino logo on a box of cereal and sell it as "Arduin-O's"

eddiea6987

the magic smoke reminds me of that show Lost.
I could print the Arduino logo on a box of cereal and sell it as "Arduin-O's"

mmcp42

did you do anything about
a)
b)
c)
or
d)
??
there are only 10 types of people
them that understands binary
and them that doesn't

eddiea6987

LOL i do have all those in place sir , i posted that for times sake i just did not draw them in , but the smoke is at bay! and connecting the resistor to 12v in fact shuts it off
I could print the Arduino logo on a box of cereal and sell it as "Arduin-O's"

mmcp42

in that case it's working
now all you need to do is get the PMW signal up and running and Bob can marry your mother's sister

(hey and less of this sir stuff!)

cheers
Mike
there are only 10 types of people
them that understands binary
and them that doesn't

eddiea6987

haha thanks for the insight!

like you said , Cheers!

(i didnt get the Bob reference) 
I could print the Arduino logo on a box of cereal and sell it as "Arduin-O's"

mmcp42

you heard the expression "Bob's your uncle"?
means it's ok!
there are only 10 types of people
them that understands binary
and them that doesn't

eddiea6987

never heard that in my 24  years hahaha but now i understand why he would marry my mothers sister.
I could print the Arduino logo on a box of cereal and sell it as "Arduin-O's"

Grumpy_Mike

Quote
the emitter of the PNP and the collector to positive 12v and the base to an arduino pwm pin

You can't do that because the only way to turn the transistor off is to put 12V on the base, the arduino can only supply 5V so there is no way to turn the transistor off. Hence it is on all the time.
You need an NPN transistor to generate a 0 to 12V signal to use to turn the PNP on and off.

mmcp42

fair cop
I was assuming (silly me) that the motor was running from 5 volts as well!)
there are only 10 types of people
them that understands binary
and them that doesn't

mmcp42

something like this?...

but you'd use 12v (can't find a suitable Fritz symbol :( )

my transistors go E B C for both
yours are different
there are only 10 types of people
them that understands binary
and them that doesn't

Grumpy_Mike


mmcp42

I guess R2 is to ensure T2 really does get turned off?
there are only 10 types of people
them that understands binary
and them that doesn't

Grumpy_Mike

Well yes R2 is the thing that keep the transistor off in the absence of an on signal. In the old days there was always a pull down resistor like this on NPN transistors as well. This was because with germanium transistors the base threshold was only 0.25V and this could be triggered by pickup.

gerg


you heard the expression "Bob's your uncle"?
means it's ok!


I had never heard that before either. Turns out, unless you live in or under rule of Britain, its not likely to have been heard.

This is a well timed thread as I was just started to read up on transistors.

Thanks.
http://maniacalbits.blogspot.com

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