Is this right?
Archiver
Posts: 46,084
I've posted some questions to this group about power supplies and
driving higher current loads with the BS-1. I appreciate all the
info I've received from the members. I still search the web and try
and strengthen my very limited knowledge.
Anyway, I was surfing and came across the following link:
http://www.acroname.com/robotics/info/articles/drivers/drivers.html
What struck me as odd was in the "What is bad about transistors?"
section. It says:
"Because of the nature of semi-conductors, the voltage of the input
(at the base) must be higher than that of the high-current load
placed across the emitter and collector. This voltage difference is
typically between 1 and 2 volts. Transistors also are limited in the
amount of current they can amplify. Many transistors can be used in
parallel to overcome this disadvantage."
Is this right?? I frequently drive 12 volt loads through a variety
of transistors connnected to the 5V stamp pin (w/ series res)...
Or, am I reading this wrong?
TIA,
Rob
driving higher current loads with the BS-1. I appreciate all the
info I've received from the members. I still search the web and try
and strengthen my very limited knowledge.
Anyway, I was surfing and came across the following link:
http://www.acroname.com/robotics/info/articles/drivers/drivers.html
What struck me as odd was in the "What is bad about transistors?"
section. It says:
"Because of the nature of semi-conductors, the voltage of the input
(at the base) must be higher than that of the high-current load
placed across the emitter and collector. This voltage difference is
typically between 1 and 2 volts. Transistors also are limited in the
amount of current they can amplify. Many transistors can be used in
parallel to overcome this disadvantage."
Is this right?? I frequently drive 12 volt loads through a variety
of transistors connnected to the 5V stamp pin (w/ series res)...
Or, am I reading this wrong?
TIA,
Rob
Comments
the load itself. Collector-emitter voltage drops runs from about .7 to
1.5VDC, depending on the tansistor and configuration you are using.
Sid Weaver
W4EKQ
Port Richey, FL
[noparse][[/noparse]Non-text portions of this message have been removed]
Most stamp apps use a BS2 pin to
turn-on/turn-off the Base of a transistor.
The Load is typically between the Collector
and a positive voltage, with a current limiting
resistor in series. The Emitter typically goes
straight to ground.
In this configuration, a +5 on the Base
(with a current limiting resistor in
series with the Base) with a
+12 on the Collector results in current flow.
A 0V on the Base with a +12 on the Collector
results in NO current flow (the Transistor is
'off', high-impedance between Collector and
Emitter).
So, the configuration being talked about in the
article is NOT the configuration you use in
controlling 12 volt loads.
--- In basicstamps@yahoogroups.com, "rrothe64" <rrothe@m...> wrote:
> I've posted some questions to this group about power supplies and
> driving higher current loads with the BS-1. I appreciate all the
> info I've received from the members. I still search the web and
try
> and strengthen my very limited knowledge.
>
> Anyway, I was surfing and came across the following link:
>
> http://www.acroname.com/robotics/info/articles/drivers/drivers.html
>
> What struck me as odd was in the "What is bad about transistors?"
> section. It says:
>
> "Because of the nature of semi-conductors, the voltage of the input
> (at the base) must be higher than that of the high-current load
> placed across the emitter and collector. This voltage difference
is
> typically between 1 and 2 volts. Transistors also are limited in
the
> amount of current they can amplify. Many transistors can be used
in
> parallel to overcome this disadvantage."
>
> Is this right?? I frequently drive 12 volt loads through a variety
> of transistors connnected to the 5V stamp pin (w/ series res)...
> Or, am I reading this wrong?
>
> TIA,
>
> Rob
controlling relays, valves,etc and also motors.
jim
http://www.geocities.com/jimforkin2003/
Original Message
From: Allan Lane [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=HnmnIBxGbLgwqZrQ__KO1oUfakWlDwQR59XcrxvLBXgmZCTI6NvTygW38KM8nlr9qGOWCX5QLw8X9HBZVf99dzwBk-UF2-w]allan.lane@h...[/url
Sent: Thursday, July 17, 2003 10:21 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Is this right?
Yes, you've read it right, BUT.
Most stamp apps use a BS2 pin to
turn-on/turn-off the Base of a transistor.
The Load is typically between the Collector
and a positive voltage, with a current limiting
resistor in series. The Emitter typically goes
straight to ground.
In this configuration, a +5 on the Base
(with a current limiting resistor in
series with the Base) with a
+12 on the Collector results in current flow.
A 0V on the Base with a +12 on the Collector
results in NO current flow (the Transistor is
'off', high-impedance between Collector and
Emitter).
So, the configuration being talked about in the
article is NOT the configuration you use in
controlling 12 volt loads.
--- In basicstamps@yahoogroups.com, "rrothe64" <rrothe@m...> wrote:
> I've posted some questions to this group about power supplies and
> driving higher current loads with the BS-1. I appreciate all the
> info I've received from the members. I still search the web and
try
> and strengthen my very limited knowledge.
>
> Anyway, I was surfing and came across the following link:
>
> http://www.acroname.com/robotics/info/articles/drivers/drivers.html
>
> What struck me as odd was in the "What is bad about transistors?"
> section. It says:
>
> "Because of the nature of semi-conductors, the voltage of the input
> (at the base) must be higher than that of the high-current load
> placed across the emitter and collector. This voltage difference
is
> typically between 1 and 2 volts. Transistors also are limited in
the
> amount of current they can amplify. Many transistors can be used
in
> parallel to overcome this disadvantage."
>
> Is this right?? I frequently drive 12 volt loads through a variety
> of transistors connnected to the 5V stamp pin (w/ series res)...
> Or, am I reading this wrong?
>
> TIA,
>
> Rob
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