Transistor chip
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Posts: 46,084
I am trying to hook up 15 lamps that work on 24 volts with .25A
each. I know that I can use any switching transistor like the
NPN2222 or other higher currnent like the NT262. But I need a more
compact solution. Can you get a Quad-transistor IC or even more than
quad? Any creative solutions?
thanks
Al
each. I know that I can use any switching transistor like the
NPN2222 or other higher currnent like the NT262. But I need a more
compact solution. Can you get a Quad-transistor IC or even more than
quad? Any creative solutions?
thanks
Al
Comments
Sid
> Try using the UL2003. Darlington array with 7 outputs.
>
> Sid
There's also one with 8 outputs but I don't remember the number.
However, I don't think the darlington array will stand 8 x .25 = 2
amps of continuous current. You might try the TI 994410 which has
four outputs rated at 1 amp each. It won't really handle an amp on
all four outputs, but it will handle 4 x .25 = 1 amp total load
pretty easily.
Chuck
Original Message
From: Chuck Davis [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=jlXZxUEVSkswHm1jpabVr7EDqLrsUMCqdOovf-Aaf2NPbthCiXazAU8KzJWLFVEf4eGxf1AzVJQl5sGe28ORgQ]cdavis@o...[/url
Sent: Thursday, October 25, 2001 9:15 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Transistor chip
--- In basicstamps@y..., Newzed@a... wrote:
> Try using the UL2003. Darlington array with 7 outputs.
>
> Sid
There's also one with 8 outputs but I don't remember the number.
However, I don't think the darlington array will stand 8 x .25 = 2
amps of continuous current. You might try the TI 994410 which has
four outputs rated at 1 amp each. It won't really handle an amp on
all four outputs, but it will handle 4 x .25 = 1 amp total load
pretty easily.
Chuck
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inrush current. If they are, measure the cold resistance of the filament
and divide into 24 for the inrush current value, which might be as high as
2 or 3 amps. Check this against absolute max instantaneous current ratings
or some such specification on the solid state device.
If you have a problem, you may be able to eliminate it by adding a resistor
in parallel with the SS switch. The idea is for the lamp to be running
warm, but not too visible, when the switch is off. Of course, your average
load goes up by doing this.
If these are LEDs you will not have a inrush issue.
I have always used a 7:1 ratio for tungsten inrush current, based on lamp
manufacturer's data and my own tests. I like your /24 approach. From where
is it derived?
Chris
>
Original Message
> From: Fred Davidson [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=qft2TccXME6rJsaJ7cXgy3p7MNVGNmWNIqQHl9SExe6qy2EpYwzZnkhsOQIzaDOsZnbl3BPFETpOEopk2ltTa40]fdavidson@m...[/url
> Sent: Thursday, October 25, 2001 10:36 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Re: Transistor chip
>
>
> If these lamps are incandescent you may wish to concern yourself with
> inrush current. If they are, measure the cold resistance of
> the filament
> and divide into 24 for the inrush current value, which might
> be as high as
> 2 or 3 amps. Check this against absolute max instantaneous
> current ratings
> or some such specification on the solid state device.
>
> If you have a problem, you may be able to eliminate it by
> adding a resistor
> in parallel with the SS switch. The idea is for the lamp to
> be running
> warm, but not too visible, when the switch is off. Of course,
> your average
> load goes up by doing this.
>
> If these are LEDs you will not have a inrush issue.
>
>
> 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.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
> The ULN2803 has 8 outputs @ 500ma. Not bad for such a compact
package.
>
But check the data sheet - I'm pretty sure the output current needs
to be de-rated depending on the number of outputs which are
conducting simultaneously.
Chuck
PS, another chip I am using is the TI TPIC595 (not sure if this is
the exact number) which is an 8 bit shift register with MOSFET power
outputs. With only three pins and a little shifting, you can drive
almost any number of outputs at fairly high current levels.
cold resistance with an ohmmeter. The 24 is from the original post
where the lamps were noted to be 24 volt lamps (or at least running at
that voltage). Hence, 24/cold_ohms = inrush current. Sorry for the
confusion!
--- In basicstamps@y..., "Chris Loiacono (E-mail)" <chris01@t...>
wrote:
> Fred:
>
> I have always used a 7:1 ratio for tungsten inrush current, based on
lamp
> manufacturer's data and my own tests. I like your /24 approach. From
where
> is it derived?
>
> Chris
>
> >
Original Message
> > From: Fred Davidson [noparse][[/noparse]mailto:fdavidson@m...]
> > Sent: Thursday, October 25, 2001 10:36 AM
> > To: basicstamps@y...
> > Subject: [noparse][[/noparse]basicstamps] Re: Transistor chip
> >
> >
> > If these lamps are incandescent you may wish to concern yourself
with
> > inrush current. If they are, measure the cold resistance of
> > the filament
> > and divide into 24 for the inrush current value, which might
> > be as high as
> > 2 or 3 amps. Check this against absolute max instantaneous
> > current ratings
> > or some such specification on the solid state device.
> >
> > If you have a problem, you may be able to eliminate it by
> > adding a resistor
> > in parallel with the SS switch. The idea is for the lamp to
> > be running
> > warm, but not too visible, when the switch is off. Of course,
> > your average
> > load goes up by doing this.
> >
> > If these are LEDs you will not have a inrush issue.
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@y...
> > from the same email address that you subscribed. Text in the
> > Subject and Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> >
> >
I missed the earlier posts and inserted foot in mouth. I've had my Dad
hospitalized for a month now, came down with a list of "flu-like" symptoms
myself the other day, etc... etc.., so I'm not running on all 8. (sorry,
Gerry - that's why I haven't gotten to your ACAD sketch yet...)
In the midst of this I am contributing on a deal that will marry two major
name brand software packages plus adding a new plug-in along with an
embedded project that will log resistive load currents over time for
predictive failure analysis (I enjoy this stuff much more!), and the post
caught my attention. Working with changing filament temperatures has proved
to be a real challenge.
Has anyone out there done anything like this before? have any words of
wisdom to share?
If so, I'll flag em and read them next week when I'm feeling better....
Chris
>
Original Message
> From: Fred Davidson [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=UjyBYuHMY0uFMB_wJQwBzl1Au_cR1QzptPpnTgNpikeqWcd55VT_RVUKyI0hp0VMNZknoHzbWQ0DWEuJnw]fdavidson@m...[/url
> Sent: Thursday, October 25, 2001 2:43 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Re: Transistor chip
>
>
> I have used 7:1 a lot myself. But it's real accurate to measure the
> cold resistance with an ohmmeter. The 24 is from the original post
> where the lamps were noted to be 24 volt lamps (or at least
> running at
> that voltage). Hence, 24/cold_ohms = inrush current. Sorry for the
> confusion!
>
Try looking at the Allegro site
http://www.allegromicro.com/selguide/sink1.asp.htm. I think some of their
high current devices come in packages with 8 devices (
http://www.allegromicro.com/sf/2596/index.htm ). Look for the total package
disipation if you plan to have multiple devices turned on at one time.
Mike
At 06:03 PM 10/24/2001 +0000, you wrote:
>I am trying to hook up 15 lamps that work on 24 volts with .25A
>each. I know that I can use any switching transistor like the
>NPN2222 or other higher currnent like the NT262. But I need a more
>compact solution. Can you get a Quad-transistor IC or even more than
>quad? Any creative solutions?
>
>
>thanks
>
>Al
>
>
>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.
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
_________________________________
Mike Walsh
walsh@i...
[noparse][[/noparse]Non-text portions of this message have been removed]
currents constantly running. The lamps would last longer this way as well.
How about using inrush limiters? Digikey sells some of Thermometric's
devices
http://www.digikey.com/scripts/us/dksus.dll?Criteria?Ref=84480&Cat=20710182
Mike
At 04:22 PM 10/25/2001 -0400, you wrote:
>Has anyone out there done anything like this before? have any words of
>wisdom to share?
>If so, I'll flag em and read them next week when I'm feeling better....
_________________________________
Mike Walsh
walsh@i...
[noparse][[/noparse]Non-text portions of this message have been removed]
Original Message
From: "Fred Davidson" <fdavidson@m...>
To: <basicstamps@yahoogroups.com>
Sent: Thursday, October 25, 2001 4:36 PM
Subject: [noparse][[/noparse]basicstamps] Re: Transistor chip
> If you have a problem, you may be able to eliminate it by adding a resistor
> in parallel with the SS switch. The idea is for the lamp to be running
> warm, but not too visible, when the switch is off. Of course, your average
> load goes up by doing this.
>
> If these are LEDs you will not have a inrush issue.
>
This solution is (was?) used to spare the switches and lamps in traffic lights
etc.
It allows also to monitor the health of the circuit + lamp.
Regards
ECO