Transistor Question
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I have the homework board that comes with the what's a
microcontroller kit. When I hook a 2n3904 transistor to Vin and
ground and then bias the transistor I only get about 4.5 volts from
the emmitor to the collector. Shouldn't I be getting more like 8? I
used a resistor on the base with varying values between 1000 and 50k.
Didn't change the output voltage at all. I need more voltage for the
motor I'm trying to run.
Any advice would be great.
microcontroller kit. When I hook a 2n3904 transistor to Vin and
ground and then bias the transistor I only get about 4.5 volts from
the emmitor to the collector. Shouldn't I be getting more like 8? I
used a resistor on the base with varying values between 1000 and 50k.
Didn't change the output voltage at all. I need more voltage for the
motor I'm trying to run.
Any advice would be great.
Comments
<billdoser2003@y...> wrote:
> I have the homework board that comes with the what's a
> microcontroller kit. When I hook a 2n3904 transistor to Vin and
> ground and then bias the transistor I only get about 4.5 volts from
> the emmitor to the collector. Shouldn't I be getting more like 8? I
> used a resistor on the base with varying values between 1000 and
50k.
> Didn't change the output voltage at all. I need more voltage for
the
> motor I'm trying to run.
>
> Any advice would be great.
I will assume you want to control the motor by letting the stamp
turn the transistor on and off.
First, make sure your connections are correct:
+ power supply voltage to one motor lead.
other motor lead to the Collector of the transistor
Emitter of transistor to 0 volts
Base of transistor through 1K resitor to stamp pin.
When stamp pin is high, transistor is on and motor runs. When
stamp pin is low, transistor is off and motor stops.
You can use the same connection and the PWM command to give you
variable speed.
Cheers,
Tom Sisk
> --- In basicstamps@yahoogroups.com, "billdoser2003"
> <billdoser2003@y...> wrote:
> > I have the homework board that comes with the what's a
> > microcontroller kit. When I hook a 2n3904 transistor to Vin and
> > ground and then bias the transistor I only get about 4.5 volts
from
> > the emmitor to the collector. Shouldn't I be getting more like 8?
I
> > used a resistor on the base with varying values between 1000 and
> 50k.
> > Didn't change the output voltage at all. I need more voltage for
> the
> > motor I'm trying to run.
> >
> > Any advice would be great.
>
> I will assume you want to control the motor by letting the stamp
> turn the transistor on and off.
>
> First, make sure your connections are correct:
>
> + power supply voltage to one motor lead.
> other motor lead to the Collector of the transistor
> Emitter of transistor to 0 volts
> Base of transistor through 1K resitor to stamp pin.
>
> When stamp pin is high, transistor is on and motor runs. When
> stamp pin is low, transistor is off and motor stops.
>
> You can use the same connection and the PWM command to give you
> variable speed.
>
> Cheers,
> Tom Sisk
Thanks for replying Tom. I have all that correct but I'm not able to
get the motor to turn. I put a Volt/Ohm meter from the emmiter to the
collector and I'm only reading about 4.5 volts even though it is
connected to the Vin which as I understand it should be the 9V from
the battery. I'm able to power LED's and such what not but I was
expecting a higher voltage reading. What can I do to increase it?
Thanks again for any additional responses.
Bill
<billdoser2003@y...> wrote:
> --- In basicstamps@yahoogroups.com, "stamptrol" <sisk1404@n...>
wrote:
> > --- In basicstamps@yahoogroups.com, "billdoser2003"
> > <billdoser2003@y...> wrote:
> > > I have the homework board that comes with the what's a
> > > microcontroller kit. When I hook a 2n3904 transistor to Vin and
> > > ground and then bias the transistor I only get about 4.5 volts
> from
> > > the emmitor to the collector. Shouldn't I be getting more like
8?
> I
> > > used a resistor on the base with varying values between 1000
and
> > 50k.
> > > Didn't change the output voltage at all. I need more voltage
for
> > the
> > > motor I'm trying to run.
> > >
> > > Any advice would be great.
> >
> > I will assume you want to control the motor by letting the
stamp
> > turn the transistor on and off.
> >
> > First, make sure your connections are correct:
> >
> > + power supply voltage to one motor lead.
> > other motor lead to the Collector of the transistor
> > Emitter of transistor to 0 volts
> > Base of transistor through 1K resitor to stamp pin.
> >
> > When stamp pin is high, transistor is on and motor runs.
When
> > stamp pin is low, transistor is off and motor stops.
> >
> > You can use the same connection and the PWM command to give
you
> > variable speed.
> >
> > Cheers,
> > Tom Sisk
>
> Thanks for replying Tom. I have all that correct but I'm not able
to
> get the motor to turn. I put a Volt/Ohm meter from the emmiter to
the
> collector and I'm only reading about 4.5 volts even though it is
> connected to the Vin which as I understand it should be the 9V from
> the battery. I'm able to power LED's and such what not but I was
> expecting a higher voltage reading. What can I do to increase it?
>
> Thanks again for any additional responses.
>
> Bill
Hi again Bill,
I just checked the specs on that transistor and its only rated
for 0.6 amps in the ECG cross-reference book. Thats not much to be
using with a motor of any size. If you're reading 4.5 volts C-E while
drawing any current, you'll quickly exceed the power rating of the
transistor, which is 0.5 watts.
Try replacing it with an IRL520 or IRL510 which are power FETs
made for switching service. Connect the + to the motor as before,
second motor lead to Drain, Source to ground. Connect the Gate
directly to the stamp pin. Better turn-off can be achieved by also
putting 10K resistor from Gate to Source.
Tom
Try those prices and shipping quantities at Digikey, Mouser, anywhere.....
You won't do better unless you buy 8 million at a time.
Ken
GO RANDY!!
===================================
Hi Bill,
Would .67 each for the IRL520 and 1.85 shipping per order (including quality
anti-static packing) be more agreeable? [noparse]:o[/noparse])
http://www.glitchbuster.com/#xstrs
(Warning: shameless self promotion -- this is my site.)
-Randy
www.glitchbuster.com
[noparse][[/noparse]Non-text portions of this message have been removed]
>
> I just checked the specs on that transistor and its only rated
> for 0.6 amps in the ECG cross-reference book. Thats not much to be
> using with a motor of any size. If you're reading 4.5 volts C-E
while
> drawing any current, you'll quickly exceed the power rating of the
> transistor, which is 0.5 watts.
>
>
> Try replacing it with an IRL520 or IRL510 which are power FETs
> made for switching service. Connect the + to the motor as before,
> second motor lead to Drain, Source to ground. Connect the Gate
> directly to the stamp pin. Better turn-off can be achieved by also
> putting 10K resistor from Gate to Source.
>
> Tom
Thanks for the help again tom. I looked up that part on Jameco. looks
like it will do the trick. Got any Idea of a part that I can pick up
at my local radio shack that will do the trick? Don't want to pay
$5.00 for delivery of a $.69 part.
Thanks gain.... or again I should say
Would .67 each for the IRL520 and 1.85 shipping per order (including quality
anti-static packing) be more agreeable? [noparse]:o[/noparse])
http://www.glitchbuster.com/#xstrs
(Warning: shameless self promotion -- this is my site.)
-Randy
www.glitchbuster.com
Original Message
From: "billdoser2003" <billdoser2003@y...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, June 16, 2004 9:19 PM
Subject: [noparse][[/noparse]basicstamps] Re: Transistor Question
> > Hi again Bill,
> >
> > I just checked the specs on that transistor and its only rated
> > for 0.6 amps in the ECG cross-reference book. Thats not much to be
> > using with a motor of any size. If you're reading 4.5 volts C-E
> while
> > drawing any current, you'll quickly exceed the power rating of the
> > transistor, which is 0.5 watts.
> >
> >
> > Try replacing it with an IRL520 or IRL510 which are power FETs
> > made for switching service. Connect the + to the motor as before,
> > second motor lead to Drain, Source to ground. Connect the Gate
> > directly to the stamp pin. Better turn-off can be achieved by also
> > putting 10K resistor from Gate to Source.
> >
> > Tom
>
> Thanks for the help again tom. I looked up that part on Jameco. looks
> like it will do the trick. Got any Idea of a part that I can pick up
> at my local radio shack that will do the trick? Don't want to pay
> $5.00 for delivery of a $.69 part.
>
> Thanks gain.... or again I should say
>
>
>
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>
-Randy
www.glitchbuster.com
> Not shameless at all !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>
> Try those prices and shipping quantities at Digikey, Mouser,
anywhere.....
>
> You won't do better unless you buy 8 million at a time.
>
> Ken
>
> GO RANDY!!
> ===================================
>
> Hi Bill,
>
> Would .67 each for the IRL520 and 1.85 shipping per order (including
quality
> anti-static packing) be more agreeable? [noparse]:o[/noparse])
>
> http://www.glitchbuster.com/#xstrs
>
> (Warning: shameless self promotion -- this is my site.)
>
> -Randy
> www.glitchbuster.com