2n4401
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Got another question I can't seem to answer. I am trying to drive a
relay with the full amount of current which is about 140ma. I am
using a 2N4401 and the max I can get out if it is 137ms, which is ok
but in order to get that I need to forward bias my transistor with
870mv. I would assume that the 870mv (that's with a 1k resistor at
the base, it's kind of small) will damage my transistor over time. I
increased the base resistor and of course it lowered the voltage but
it also lowered the current. Is there another way to make this work
or can anyone suggest another transistor with a TO-92 pkg? Thanks,
Chris
relay with the full amount of current which is about 140ma. I am
using a 2N4401 and the max I can get out if it is 137ms, which is ok
but in order to get that I need to forward bias my transistor with
870mv. I would assume that the 870mv (that's with a 1k resistor at
the base, it's kind of small) will damage my transistor over time. I
increased the base resistor and of course it lowered the voltage but
it also lowered the current. Is there another way to make this work
or can anyone suggest another transistor with a TO-92 pkg? Thanks,
Chris
Comments
>Got another question I can't seem to answer. I am trying to drive a
>relay with the full amount of current which is about 140ma. I am
>using a 2N4401 and the max I can get out if it is 137ms, which is ok
>but in order to get that I need to forward bias my transistor with
>870mv. I would assume that the 870mv (that's with a 1k resistor at
>the base, it's kind of small) will damage my transistor over time. I
>increased the base resistor and of course it lowered the voltage but
>it also lowered the current. Is there another way to make this work
>or can anyone suggest another transistor with a TO-92 pkg? Thanks,
How much base current? In other words, what drives the 1K resistor? If it
is coming from the Stamp, you are fine. In fact, you could come as low as
470R without damaging anything.
dwayne
--
Dwayne Reid <dwayner@p...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax
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Thanks for the reply. With 470R at the base the current is
approximately 7.42ma. With 1k at the base (and yes, it's coming from
the stamp) the current is 3.91ma. So, are you saying that the
voltage being .9 won't hurt it, it's the current that will?
>Dwayne,
>
> Thanks for the reply. With 470R at the base the current is
>approximately 7.42ma. With 1k at the base (and yes, it's coming from
>the stamp) the current is 3.91ma. So, are you saying that the
>voltage being .9 won't hurt it, it's the current that will?
Exactly right! You should have no problems with the above.
dwayne
--
Dwayne Reid <dwayner@p...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax
Celebrating 18 years of Engineering Innovation (1984 - 2002)
.-. .-. .-. .-. .-. .-. .-. .-. .-. .-
`-' `-' `-' `-' `-' `-' `-' `-' `-'
Do NOT send unsolicited commercial email to this email address.
This message neither grants consent to receive unsolicited
commercial email nor is intended to solicit commercial email.