Are buffers ( CMOS 4050 etc) any use to protect the stamp''s outputs???
Archiver
Posts: 46,084
The ULN2803 already has a resistor in the base circuit so it's not
necessary to add another. You should, of course, retrieve the ULN2803
specs from the web for details on current. Keep in mind that it is a
Darlington array and provides ground (sinks current) to external
devices. Since the ULN2803 is controlling the current to the device,
you don't have to worry about the Stamp; the effect on the Stamp is very
small (so long as you're not trying to switch the Stamp's Vdd output!),
hence the advantage of using the ULN2803.
Here's a helpful article written by "Stamp Applications" creator Scott
Edwards:
http://www.parallax.com/dl/docs/cols/nv/vol1/col/6.pdf
It covers the use of transistors and other devices (including the
ULN2x03) for switching big loads with a Stamp.
-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office
Original Message
From: arridh_shashank [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=xjA1khdBQkwMOUUu9KL3HOuZXQ41AH2sxMSx1fTX-Mc6YYmVHCf0TIpZSLElLb2afIWBB4fM46U22BH9-LVxiNR7YTo]arridh_shashank@y...[/url
Sent: Monday, December 29, 2003 8:47 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Are buffers ( CMOS 4050 etc) any use to
protect the stamp's outputs???
Hi Jon
So all I would need to do to protect my stamp from excessive current
sourcing would be to add 220 Ohm resistors in series? Can I then
connect a ULN2803 or should I leave out the 220 Ohm if I am
connecting it? Also what is the maximum current a 2803 would source
from the stamp to drive its maximum 500 milli amp Load? I have been
unable to work this out.
Many thanks
Arridh
--- In basicstamps@yahoogroups.com, "Jon Williams" <jwilliams@p...>
wrote:
> If you're simply looking to protect your Stamp you can put 220 ohm
> resistors in series with your outputs; we do this on the Homework
Board
> (BS2) and BS1 Project Board -- both boards are designed for
students.
> You may want to consider buffers if you need more current than the
Stamp
> can safely sink or source.
>
> -- Jon Williams
> -- Applications Engineer, Parallax
> -- Dallas Office
>
>
>
Original Message
> From: arridh_shashank [noparse][[/noparse]mailto:arridh_shashank@y...]
> Sent: Monday, December 29, 2003 1:36 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Are buffers ( CMOS 4050 etc) any use to
protect
> the stamp's outputs???
>
>
> Hey
>
> I'm not sure my self if this will work or not so I thought I'd ask
> you guys [noparse]:D[/noparse]. I wanted to protect my stamp outputs from gettin
> damaged by sourcing and sinking too much current so I looked
around
> and found the cmos 4050 chip non inverting hex buffer. I was
> wondering if it will protect my stamp from sourcing and sinking a
> lot of current. What I plan to do is to use it as a intermediate
> between my stamp and my output device so as to protect the stamp.
> Would this be a benifitial setup to have and is this the use the
> chip was developed for? Furthermore will it protect my stamp from
> damage in the instance that a large base current was drawn by a
> transistor or similar instance? Any light you guys can shed on the
> subject would be helpful.
>
> Many thanks
> Arridh
>
>
>
> 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
>
> To visit your group on the web, go to:
> http://groups.yahoo.com/group/basicstamps/
>
> To unsubscribe from this group, send an email to:
> basicstamps-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject to:
> http://docs.yahoo.com/info/terms/
>
>
>
>
> This message has been scanned by WebShield. Please report SPAM to
> abuse@p...
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
To visit your group on the web, go to:
http://groups.yahoo.com/group/basicstamps/
To unsubscribe from this group, send an email to:
basicstamps-unsubscribe@yahoogroups.com
Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
This message has been scanned by WebShield. Please report SPAM to
abuse@p....
necessary to add another. You should, of course, retrieve the ULN2803
specs from the web for details on current. Keep in mind that it is a
Darlington array and provides ground (sinks current) to external
devices. Since the ULN2803 is controlling the current to the device,
you don't have to worry about the Stamp; the effect on the Stamp is very
small (so long as you're not trying to switch the Stamp's Vdd output!),
hence the advantage of using the ULN2803.
Here's a helpful article written by "Stamp Applications" creator Scott
Edwards:
http://www.parallax.com/dl/docs/cols/nv/vol1/col/6.pdf
It covers the use of transistors and other devices (including the
ULN2x03) for switching big loads with a Stamp.
-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office
Original Message
From: arridh_shashank [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=xjA1khdBQkwMOUUu9KL3HOuZXQ41AH2sxMSx1fTX-Mc6YYmVHCf0TIpZSLElLb2afIWBB4fM46U22BH9-LVxiNR7YTo]arridh_shashank@y...[/url
Sent: Monday, December 29, 2003 8:47 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Are buffers ( CMOS 4050 etc) any use to
protect the stamp's outputs???
Hi Jon
So all I would need to do to protect my stamp from excessive current
sourcing would be to add 220 Ohm resistors in series? Can I then
connect a ULN2803 or should I leave out the 220 Ohm if I am
connecting it? Also what is the maximum current a 2803 would source
from the stamp to drive its maximum 500 milli amp Load? I have been
unable to work this out.
Many thanks
Arridh
--- In basicstamps@yahoogroups.com, "Jon Williams" <jwilliams@p...>
wrote:
> If you're simply looking to protect your Stamp you can put 220 ohm
> resistors in series with your outputs; we do this on the Homework
Board
> (BS2) and BS1 Project Board -- both boards are designed for
students.
> You may want to consider buffers if you need more current than the
Stamp
> can safely sink or source.
>
> -- Jon Williams
> -- Applications Engineer, Parallax
> -- Dallas Office
>
>
>
Original Message
> From: arridh_shashank [noparse][[/noparse]mailto:arridh_shashank@y...]
> Sent: Monday, December 29, 2003 1:36 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Are buffers ( CMOS 4050 etc) any use to
protect
> the stamp's outputs???
>
>
> Hey
>
> I'm not sure my self if this will work or not so I thought I'd ask
> you guys [noparse]:D[/noparse]. I wanted to protect my stamp outputs from gettin
> damaged by sourcing and sinking too much current so I looked
around
> and found the cmos 4050 chip non inverting hex buffer. I was
> wondering if it will protect my stamp from sourcing and sinking a
> lot of current. What I plan to do is to use it as a intermediate
> between my stamp and my output device so as to protect the stamp.
> Would this be a benifitial setup to have and is this the use the
> chip was developed for? Furthermore will it protect my stamp from
> damage in the instance that a large base current was drawn by a
> transistor or similar instance? Any light you guys can shed on the
> subject would be helpful.
>
> Many thanks
> Arridh
>
>
>
> 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
>
> To visit your group on the web, go to:
> http://groups.yahoo.com/group/basicstamps/
>
> To unsubscribe from this group, send an email to:
> basicstamps-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject to:
> http://docs.yahoo.com/info/terms/
>
>
>
>
> This message has been scanned by WebShield. Please report SPAM to
> abuse@p...
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
To visit your group on the web, go to:
http://groups.yahoo.com/group/basicstamps/
To unsubscribe from this group, send an email to:
basicstamps-unsubscribe@yahoogroups.com
Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
This message has been scanned by WebShield. Please report SPAM to
abuse@p....