1.5V, 2-NPN White LED Driver Circuit (LTspice)

[Bill Garber]

message : Bill Garber wrote:
: >
message
: > : > : I read in sci.electronics.design that R.Lewis
: > <[email protected]>
: > : wrote (in <[email protected]>) about '1.5V,
2-NPN
: > White LED
: > : Driver Circuit (LTspice)', on Wed, 7 Jan 2004:
: > : >Why do you have to click on 'Start' when you want to stop
: > Windows?
: > : >
: > : You don't. Wait a few minutes and it will stop by itself,
with
: > a pretty
: > : blue screen. (;-)
: >
: > Mine is Maroon now. Get a program called BSOD.EXE
: > when you are sick of the Blue, change it to whatever
: > suits you. ;-)
: >
: > Bill
:
: My last computer was set for a blood red screen. I think I
used
: Tweek-UI to change it.

Yeah, that works too. I don't particularly
like Tweaking programs. Some of them tend to
change things in an undesirable way.

: Also, a Monty Python character yelled, "You started it, you
bleeding
: pig!" when you closed Windows on my last machine that ran Win
3.11.

I had a startling startup sound so I would
know when my kids were on it from the other
room. ;-) They didn't like it though.

Bill @ GarberStreet Enterprizez };-)
Web Site - http://garberstreet.netfirms.com
Email - [email protected]
Remove - SPAM and X to contact me

 

[R.Lewis]

:
: "R.Lewis" <h.lewis-not this [email protected]> schreef in
bericht
: : > Why do you have to click on 'Start' when you want to stop
Windows?
:
: I heard a lot of rumours about it. I remember only two of them:
:
: - Windows is so great an operating system that nowbody ever
wants to stop
: it.
:
: - The developers simply forgot the stop button as they never
needed it.
:
: If anyone knows better, I like to hear it. Always in the mood
of learning
: something new.
:
: petrus

I can't quote this, but I read somewhere that Bill Gates
himself had told a group that you press START to initiate
any function, and since SHUT DOWN is a function..........

Bill @ GarberStreet Enterprizez };-)

Ah - now I see
(as the blind man said as he fell down a hole)

 

[Louis Bybee]

:
: "R.Lewis" <h.lewis-not this [email protected]> schreef in
bericht
: : > Why do you have to click on 'Start' when you want to stop
Windows?
:
: I heard a lot of rumours about it. I remember only two of them:
:
: - Windows is so great an operating system that nowbody ever
wants to stop
: it.
:
: - The developers simply forgot the stop button as they never
needed it.
:
: If anyone knows better, I like to hear it. Always in the mood
of learning
: something new.
:
: petrus

I can't believe with the high number of intelligent people frequenting these
groups that you all missed the obvious!

Bill & Co. didn't have to include a stop button as it would have duplicated
a feature already existing in the software!

The OS was designed to crash, or lock up often enough that it was likely
that one such occurance would coincide with your desire to stop using the
computer. :-]

Louis--
*********************************************
Remove the two fish in address to respond

 

[james]

This post presents an alternate, regulated version of a very simple
1.5V battery based white LED driver circuit from Electronic Design:

http://www.elecdesign.com/Files/29/5886/Figure_01.gif

<snip>

I've built this circuit and the one that analog posted as a LTSpice
file and they both work quite well. Is there any way to improve the
low voltage performance?

Obviously you are limited by the VBE of the bipolar transistors - can
you get low Vbe transistors?

James

 

[John Woodgate]

I read in sci.electronics.design that james <[email protected]>

Obviously you are limited by the VBE of the bipolar transistors - can
you get low Vbe transistors?

For simple, room temperature applications for personal use, it is not
unreasonable to use germanium transistors (Vbe = 0.2 to 0.3 V), and some
types are still available.

 

[Mark Jones]

In news:[email protected] (John Woodgate):

I read in sci.electronics.design that james <[email protected]>


For simple, room temperature applications for personal use, it is not
unreasonable to use germanium transistors (Vbe = 0.2 to 0.3 V), and some
types are still available.

Aaah, but can they switch any appreciable current?

 

[John Woodgate]

In (John Woodgate):


Aaah, but can they switch any appreciable current?

It depends on which devices are still available, of course. There were
some devices rated at 20 A at least, but they probably aren't available
any more. Of course, they were slow. Typical fbeta of 3 kHz, IIRC.

 

[Watson A.Name - Watt Sun, Dark Remover]

<snip>

I've built this circuit and the one that analog posted as a LTSpice
file and they both work quite well. Is there any way to improve the
low voltage performance?

I built this circuit in the above URL and it is the only one I've
managed to get to work below .7VDC, and in fact puts out a little even
at .58 VDC. That's really quite low!

The other one that was posted here, which has the 10 ohm resistor in
series with the LED's cathode lead to sense the current, is very
snotty. It sometimes fails to come on when powered on, and then draws
200 mA excessive current when it's not oscillating.

Obviously you are limited by the VBE of the bipolar transistors - can
you get low Vbe transistors?

Silicon transistors always have .6Vbe. You can use germanium which
have about .2 Vbe, but they tend to be lower current and power than
silicon. The circuit in this URL gets around this by using a starter
circuit with a JFET.
http://www.ece.uvic.ca/~jbornema/Journals/064a-97ia-jmd.pdf

James

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[Watson A.Name - Watt Sun, Dark Remover]

In (John Woodgate):


Aaah, but can they switch any appreciable current?

Ummm... How about 50 amps? Motorola's 2N2728 germanium power
transistor was made specifically for power converters operating at low
voltages. However its Vceo is only 5V.

We used to make 100 watt 12VDC to 120VAC inverters from a pair of
2N457A germanium power transistors. You can still find germanium
power transistors around. I think I saw some on Ebay.

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[John Woodgate]

I read in sci.electronics.design that Watson A. Name - Watt Sun, Dark
ews.dslextreme.com>) about '1.5V, 2-NPN White LED Driver Circuit
(LTspice)', on Sat, 10 Jan 2004:

Ummm... How about 50 amps? Motorola's 2N2728 germanium power
transistor was made specifically for power converters operating at low
voltages. However its Vceo is only 5V.

ft = 1 Hz? (;-) I remember the ADZ11 and 12, which had fbeta about 3 kHz
and not much beta.

 

[Watson A.Name - Watt Sun, Dark Remover]

It depends on which devices are still available, of course. There were
some devices rated at 20 A at least, but they probably aren't available
any more. Of course, they were slow. Typical fbeta of 3 kHz, IIRC.

I see power transistors on Ebay. Like
http://search.ebay.com/search/search.dll?cgiurl=http://cgi.ebay.
com%2Fws%2F&MfcISAPICommand=GetResult&ht=1&from=R7&ebaytag1=ebayreg&qu
ery=germanium+power&query2=germanium+power&search_option=1&exclude=&ca
tegory0=&minPrice=&maxPrice=&ebaytag1code=0&st=&SortProperty=MetaEndSo
rt

Or if that's too much, just do a search and type in germanium power.
But I fail to see why anyone would want those weird Russian power
transistors.

Go to www.nteinc.com and get the data sheet for the replacement for
2N457A, which is the NTE104, good for a hundred watts. It's a bit on
the expensive side, see mouser's listing for it.
http://www.mouser.com/index.cfm?&handler=search.listcategory&Ntt=*NTE1
04*&terms=NTE104&Dk=1&D=*NTE104*&N=0&crc=true


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Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
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[Watson A.Name - Watt Sun, Dark Remover]

I read in sci.electronics.design that Watson A. Name - Watt Sun, Dark
ews.dslextreme.com>) about '1.5V, 2-NPN White LED Driver Circuit
(LTspice)', on Sat, 10 Jan 2004:


ft = 1 Hz? (;-) I remember the ADZ11 and 12, which had fbeta about 3 kHz
and not much beta.

I went over to Fry's this afternoon to pick up a spray can of some
DeoxIT (see other thread), and I checked the price of the NTE104.
Mouser lists it for $16, and Fry's has it marked as $9.99. It has a
Ft of 10 kHz.

I used a Deltakit Mark 10 CD ignition system for many years on my van,
and it used two germanium power transistors for the inverter, both
were mounted directly to the heatsink and case because the collectors
were at ground. I had no thermal problems with them, even tho the CDI
was in the engine compartment.



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My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Michael]

:
(snip)

I used a Deltakit Mark 10 CD ignition system for many years on my van,
and it used two germanium power transistors for the inverter, both
were mounted directly to the heatsink and case because the collectors
were at ground. I had no thermal problems with them, even tho the CDI
was in the engine compartment.

Ahhh yes ... the venerable Delta CDI. A couple friends had those. That
was back in the days of disco, helmet hair, wallpaper shirts, flaired
doubleknit pants, platform shoes .....
I opted for the Heathkit CDI for my '71 Pinto. That was a goodie too.