Silicon Steroids NV Article
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Posts: 46,084
Hello Group,
I recently picked up the Basic Stamp kit at Radio Shack and have
been enjoying microcontrollers and all the possibilities ever since.
An article in a 95 NV issue has really got me dreaming up lots of
different applications that I can apply these stamps to. Although I
am still fairly new to microcontrollers and electronics, I seem to
be picking it up pretty quick. The code has been the easiest part,
it's the electronics that I am having some troubles with and so I do
have a few questions on transistors I was hoping someone might be
able to help me out.
I have a project where I want to close the contact switch (a simple
push button) on my garage door opener with a basic stamp. Instead of
pressing the button on the garage door opener, I would like the
stamp to do it using a transistor as the switch. I was thinking of
using a 2N2222.
In figure 1 of the article:
http://www.parallax.com/dl/docs/cols/nv/vol1/col/5.pdf
The base current of a 2N2222 is 11mA, the load current is 100mA and
RB of 390 ohms. I was hoping someone could explain the formula used
to calculate the value of the resistance for those values. The
reason being is that I downloaded the data sheet on a 2N2222A (ON
Semicondictor) from digi key and they are showing it has a maximum
collector current of 600mA. I would like a load current of 200 - 250
mA which I am sure will drive my base current up to close to 20+ mA.
What I am trying to avoid is exceeding the output current
limitations of my stamp pin doing the switching.
Also, maybe someone could help me out with the data sheet on the
2N2222 I am reading. There are lots of values on it and I am not
sure what they all mean yet. Could you tell me which one represents
the C-E voltage drop? I am guessing it is the Collector-Emitter
Saturation Voltage but that's only a guess. It is showing .3 for (Ic
= 150 mAdc, Ib = 150 mAdc) which is less then the .5 as listed in
the article for 100 mA which leads me to believe I might not be
looking at the right specs.
Thanks again for any help you can offer.
Lu Kwan
I recently picked up the Basic Stamp kit at Radio Shack and have
been enjoying microcontrollers and all the possibilities ever since.
An article in a 95 NV issue has really got me dreaming up lots of
different applications that I can apply these stamps to. Although I
am still fairly new to microcontrollers and electronics, I seem to
be picking it up pretty quick. The code has been the easiest part,
it's the electronics that I am having some troubles with and so I do
have a few questions on transistors I was hoping someone might be
able to help me out.
I have a project where I want to close the contact switch (a simple
push button) on my garage door opener with a basic stamp. Instead of
pressing the button on the garage door opener, I would like the
stamp to do it using a transistor as the switch. I was thinking of
using a 2N2222.
In figure 1 of the article:
http://www.parallax.com/dl/docs/cols/nv/vol1/col/5.pdf
The base current of a 2N2222 is 11mA, the load current is 100mA and
RB of 390 ohms. I was hoping someone could explain the formula used
to calculate the value of the resistance for those values. The
reason being is that I downloaded the data sheet on a 2N2222A (ON
Semicondictor) from digi key and they are showing it has a maximum
collector current of 600mA. I would like a load current of 200 - 250
mA which I am sure will drive my base current up to close to 20+ mA.
What I am trying to avoid is exceeding the output current
limitations of my stamp pin doing the switching.
Also, maybe someone could help me out with the data sheet on the
2N2222 I am reading. There are lots of values on it and I am not
sure what they all mean yet. Could you tell me which one represents
the C-E voltage drop? I am guessing it is the Collector-Emitter
Saturation Voltage but that's only a guess. It is showing .3 for (Ic
= 150 mAdc, Ib = 150 mAdc) which is less then the .5 as listed in
the article for 100 mA which leads me to believe I might not be
looking at the right specs.
Thanks again for any help you can offer.
Lu Kwan
Comments
There is a pretty good site that explains transistor performance that even
uses the 2n2222A as an example. It is :
http://pub40.ezboard.com/fbasicelectronicsfrm5.showMessage?topicID=3.topic
Remember the current on the base will be limited by what the Stamp can
deliver. and explains the 390 ohm value used on the base in your example. thet
could
be a bit lower- - as low as 250 ohms to source 20 mA or 200 ohms to sink 25
mA. No margins there, though, and remember that the total current trough all
the Stamp pins should be less that 50 mA.
The amount of current you can switch will depend on the base current times
hFE, which should be on your datasheet.
Larry
In a message dated 2/21/04 5:36:23 AM Pacific Standard Time,
basicstamps@yahoogroups.com writes:
Date: Sat, 21 Feb 2004 04:38:17 -0000
From: "lvscan" <kamikazi@r...>
Subject: Silicon Steroids NV Article
Hello Group,
I recently picked up the Basic Stamp kit at Radio Shack and have
been enjoying microcontrollers and all the possibilities ever since.
An article in a 95 NV issue has really got me dreaming up lots of
different applications that I can apply these stamps to. Although I
am still fairly new to microcontrollers and electronics, I seem to
be picking it up pretty quick. The code has been the easiest part,
it's the electronics that I am having some troubles with and so I do
have a few questions on transistors I was hoping someone might be
able to help me out.
I have a project where I want to close the contact switch (a simple
push button) on my garage door opener with a basic stamp. Instead of
pressing the button on the garage door opener, I would like the
stamp to do it using a transistor as the switch. I was thinking of
using a 2N2222.
In figure 1 of the article:
http://www.parallax.com/dl/docs/cols/nv/vol1/col/5.pdf
The base current of a 2N2222 is 11mA, the load current is 100mA and
RB of 390 ohms. I was hoping someone could explain the formula used
to calculate the value of the resistance for those values. The
reason being is that I downloaded the data sheet on a 2N2222A (ON
Semicondictor) from digi key and they are showing it has a maximum
collector current of 600mA. I would like a load current of 200 - 250
mA which I am sure will drive my base current up to close to 20+ mA.
What I am trying to avoid is exceeding the output current
limitations of my stamp pin doing the switching.
Also, maybe someone could help me out with the data sheet on the
2N2222 I am reading. There are lots of values on it and I am not
sure what they all mean yet. Could you tell me which one represents
the C-E voltage drop? I am guessing it is the Collector-Emitter
Saturation Voltage but that's only a guess. It is showing .3 for (Ic
= 150 mAdc, Ib = 150 mAdc) which is less then the .5 as listed in
the article for 100 mA which leads me to believe I might not be
looking at the right specs.
Thanks again for any help you can offer.
Lu Kwan
[noparse][[/noparse]Non-text portions of this message have been removed]
lvscan <kamikazi@r...> wrote:Hello Group,
I recently picked up the Basic Stamp kit at Radio Shack and have
been enjoying microcontrollers and all the possibilities ever since.
An article in a 95 NV issue has really got me dreaming up lots of
different applications that I can apply these stamps to. Although I
am still fairly new to microcontrollers and electronics, I seem to
be picking it up pretty quick. The code has been the easiest part,
it's the electronics that I am having some troubles with and so I do
have a few questions on transistors I was hoping someone might be
able to help me out.
I have a project where I want to close the contact switch (a simple
push button) on my garage door opener with a basic stamp. Instead of
pressing the button on the garage door opener, I would like the
stamp to do it using a transistor as the switch. I was thinking of
using a 2N2222. The .3 volts C to E drop @ 150mA collector current sounds
reasonable. I would expect the current gain or ratio of collector current to
base current to be much higher. I looked at the link below and it shows 15 mA
base current for 150 mA collector current. That makes the gain 10. I'm pretty
sure 200 mA base current would be a defective part. I hope the link works. Good
luck.
www.semiconductors.philips.com/acrobat/ datasheets/PN2222A_3.pdf
In figure 1 of the article:
http://www.parallax.com/dl/docs/cols/nv/vol1/col/5.pdf
The base current of a 2N2222 is 11mA, the load current is 100mA and
RB of 390 ohms. I was hoping someone could explain the formula used
to calculate the value of the resistance for those values. The
reason being is that I downloaded the data sheet on a 2N2222A (ON
Semicondictor) from digi key and they are showing it has a maximum
collector current of 600mA. I would like a load current of 200 - 250
mA which I am sure will drive my base current up to close to 20+ mA.
What I am trying to avoid is exceeding the output current
limitations of my stamp pin doing the switching.
Also, maybe someone could help me out with the data sheet on the
2N2222 I am reading. There are lots of values on it and I am not
sure what they all mean yet. Could you tell me which one represents
the C-E voltage drop? I am guessing it is the Collector-Emitter
Saturation Voltage but that's only a guess. It is showing .3 for (Ic
= 150 mAdc, Ib = 150 mAdc) which is less then the .5 as listed in
the article for 100 mA which leads me to believe I might not be
looking at the right specs.
Thanks again for any help you can offer.
Lu Kwan
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[noparse][[/noparse]Non-text portions of this message have been removed]
I did not get your complete reply... Not sure what you were getting
at.
Thanks for any help you can offer since I have not been able to
tackle this problem yet.
Lu Kwan
--- In basicstamps@yahoogroups.com, PHILIP GAMBLIN
<gremlin8650@y...> wrote:
> I don't have a data sheet to the 2n2222a but, take another look.
The d
>
> lvscan <kamikazi@r...> wrote:Hello Group,
>
> I recently picked up the Basic Stamp kit at Radio Shack and have
> been enjoying microcontrollers and all the possibilities ever
since.
>
> An article in a 95 NV issue has really got me dreaming up lots of
> different applications that I can apply these stamps to. Although
I
> am still fairly new to microcontrollers and electronics, I seem to
> be picking it up pretty quick. The code has been the easiest part,
> it's the electronics that I am having some troubles with and so I
do
> have a few questions on transistors I was hoping someone might be
> able to help me out.
>
> I have a project where I want to close the contact switch (a
simple
> push button) on my garage door opener with a basic stamp. Instead
of
> pressing the button on the garage door opener, I would like the
> stamp to do it using a transistor as the switch. I was thinking of
> using a 2N2222. The .3 volts C to E drop @ 150mA collector current
sounds reasonable. I would expect the current gain or ratio of
collector current to base current to be much higher. I looked at the
link below and it shows 15 mA base current for 150 mA collector
current. That makes the gain 10. I'm pretty sure 200 mA base current
would be a defective part. I hope the link works. Good luck.
> www.semiconductors.philips.com/acrobat/ datasheets/PN2222A_3.pdf
> In figure 1 of the article:
>
> http://www.parallax.com/dl/docs/cols/nv/vol1/col/5.pdf
>
> The base current of a 2N2222 is 11mA, the load current is 100mA
and
> RB of 390 ohms. I was hoping someone could explain the formula
used
> to calculate the value of the resistance for those values. The
> reason being is that I downloaded the data sheet on a 2N2222A (ON
> Semicondictor) from digi key and they are showing it has a maximum
> collector current of 600mA. I would like a load current of 200 -
250
> mA which I am sure will drive my base current up to close to 20+
mA.
> What I am trying to avoid is exceeding the output current
> limitations of my stamp pin doing the switching.
>
> Also, maybe someone could help me out with the data sheet on the
> 2N2222 I am reading. There are lots of values on it and I am not
> sure what they all mean yet. Could you tell me which one
represents
> the C-E voltage drop? I am guessing it is the Collector-Emitter
> Saturation Voltage but that's only a guess. It is showing .3 for
(Ic
> = 150 mAdc, Ib = 150 mAdc) which is less then the .5 as listed in
> the article for 100 mA which leads me to believe I might not be
> looking at the right specs.
>
> Thanks again for any help you can offer.
>
> Lu Kwan
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
Subject and Body of the message will be ignored.
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
>
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> Yahoo! Finance Tax Center - File online. File on time.
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
zero voltage drop, don't care about open circuit voltage up to their rated
voltage, and polarity is a non-issue. Just don't try to push a lot of
current through them. You can buy them for less than a buck, and some can be
directly driven by the Stamp's output without a buffer. If you want to drive
one directly from a Stamp, make sure the coil is rated to be driven by TTL
circuits directly and has a protection diode.
Mike Sokol
mike@f...
www.fitsandstarts.com
" One should not increase, beyond what is necessary,
the number of entities required to explain anything"...
-William of Occam-
Original Message
From: "PHILIP GAMBLIN" <gremlin8650@y...>
To: <basicstamps@yahoogroups.com>
Sent: Tuesday, March 30, 2004 11:30 PM
Subject: Re: [noparse][[/noparse]basicstamps] Silicon Steroids NV Article
> I don't have a data sheet to the 2n2222a but, take another look. The d
>
> lvscan <kamikazi@r...> wrote:Hello Group,
>
> I recently picked up the Basic Stamp kit at Radio Shack and have
> been enjoying microcontrollers and all the possibilities ever since.
>
> An article in a 95 NV issue has really got me dreaming up lots of
> different applications that I can apply these stamps to. Although I
> am still fairly new to microcontrollers and electronics, I seem to
> be picking it up pretty quick. The code has been the easiest part,
> it's the electronics that I am having some troubles with and so I do
> have a few questions on transistors I was hoping someone might be
> able to help me out.
>
> I have a project where I want to close the contact switch (a simple
> push button) on my garage door opener with a basic stamp. Instead of
> pressing the button on the garage door opener, I would like the
> stamp to do it using a transistor as the switch. I was thinking of
> using a 2N2222. The .3 volts C to E drop @ 150mA collector current sounds
reasonable. I would expect the current gain or ratio of collector current
to base current to be much higher. I looked at the link below and it shows
15 mA base current for 150 mA collector current. That makes the gain 10.
I'm pretty sure 200 mA base current would be a defective part. I hope the
link works. Good luck.
> www.semiconductors.philips.com/acrobat/ datasheets/PN2222A_3.pdf
> In figure 1 of the article:
>
> http://www.parallax.com/dl/docs/cols/nv/vol1/col/5.pdf
>
> The base current of a 2N2222 is 11mA, the load current is 100mA and
> RB of 390 ohms. I was hoping someone could explain the formula used
> to calculate the value of the resistance for those values. The
> reason being is that I downloaded the data sheet on a 2N2222A (ON
> Semicondictor) from digi key and they are showing it has a maximum
> collector current of 600mA. I would like a load current of 200 - 250
> mA which I am sure will drive my base current up to close to 20+ mA.
> What I am trying to avoid is exceeding the output current
> limitations of my stamp pin doing the switching.
>
> Also, maybe someone could help me out with the data sheet on the
> 2N2222 I am reading. There are lots of values on it and I am not
> sure what they all mean yet. Could you tell me which one represents
> the C-E voltage drop? I am guessing it is the Collector-Emitter
> Saturation Voltage but that's only a guess. It is showing .3 for (Ic
> = 150 mAdc, Ib = 150 mAdc) which is less then the .5 as listed in
> the article for 100 mA which leads me to believe I might not be
> looking at the right specs.
>
> Thanks again for any help you can offer.
>
> Lu Kwan
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
>
> Do you Yahoo!?
> Yahoo! Finance Tax Center - File online. File on time.
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
> Yahoo! Groups Links
>
>
>
>
>
>
>