1.5v to 3.3v LED circuit

Looking to drive a white superbright led (1-4) from 1.5v to 2.5v battery, led requires 3.3v @ 20ma, is there a suitable small circuit, or single chip device

TIA

Reply to
LED Man
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   Robert Monsen
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Reply to
Robert Monsen

An NPN, a 1.5V AA battery, two resistors, a capacitor, a diode and a simple, hand-wound threaded toroidal. D2 can be a diode-connected 2N3904, a 1N4148, or a Schottky like a 1N5817-1N5819.

V+ V+ V+ | | | | | | | )|. .|( (about 50" of | )| |( magnet wire | )| T1 |( for both | + )| |( windings) --- | | - B1 | | D2 R2 --- \ +---|>|---+---/\/\---, - / R1 | | 220 | | \ 2200 | | | | / | | | | | |/c Q1 | --- ~ | '------| 2N3904 --- C1 \ / ~ | |>e --- 100uF --- LED | (B1 > 1V) | | | | | | | gnd gnd gnd gnd

It will drain a AA battery fairly completely, before quitting.

Jon

Reply to
Jonathan Kirwan

Jon...

I have a hell of a time with ASCII schematics. Could you possibly post a "real" schematic to alt.binaries.schematics.electronic?

Jim

Reply to
RST Engineering (jw)

copy into notepad and then format -> font -> "fixedsys"

Reply to
CWatters

You should be able to set your newsreader for a fixed font. I use Courier.

Cheers! Rich

Reply to
Rich Grise

I have Courier as my default font and I still have a hell of a time reading an ASCII schematic. Sorry.

Jim

Reply to
RST Engineering (jw)

Is it an inability to recognize the symbols?

I guess I'm asking this because it took me exactly zero time to see and understand an ASCII schematic the first time I saw one and I've had very little trouble ever after, so I'm honestly curious about what makes this difficult for some -- I completely lack the personal experience to understand the trouble, so I'd appreciate any clues about what you perceive and don't perceive.

Meanwhile, I'll try and load over a schematic in some format you can see. I have a few other things to take care of before I struggle with that, though.

Jon

Reply to
Jonathan Kirwan

"LED Man" schreef in bericht news:1gs7o6k.2zw8mq1hphlgwN% snipped-for-privacy@3v.invalid...

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Just some google results. There are much more of them.

petrus bitbyter

Reply to
petrus bitbyter

I'll have to throw in with petrus here, then. What's the hard part?

Do your ASCII schematics not look like this one?:

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Good Luck! Rich

Reply to
Rich Grise

No, they don't. The link you sent was quite readable. The schematic in this newsreader was highly compressed in the x dimension and absolutely unreadable. However, as I sit here and look, the fact that I've got my settings to Courier doesn't seem to make a difference. Just looking at this font I can tell it is a variant of Helvetica, or Arial, or whatever other san-serif font you want to call it.

I need to do some more investigation as to why it looks like this. Or perhaps only the OUTGOING messages look like this...

Thanks,

Jim

Reply to
RST Engineering (jw)

Lordy, Outlook Express makes you change the font in no less than THREE places in order to force messages to Courier. THe default fixed width, the default proportional width, and the little checkbox on the "advanced" tab to default all incoming messages to the default settings.

Windoze does it again.

Thanks for the help, Rich...

Jim

Reply to
RST Engineering (jw)

the

to

If you use OE and the font is not set to default to a fixed width font, you can select 'view' then move down to 'text size' then move to 'fixed' to see it on the ASCII art on the fly.

Reply to
Lord Garth

schematic in

absolutely

got my

looking at this

whatever other

this. Or

GMAB Why bother to explain, He's a top poster, his inability to understand anything is clear. He thinks upside down! (:>)

Reply to
Clarence_A

or

simple,

1N4148, or

I really despise those who suggest that the 2N3904 is capable of doing this job adequately. With that wimpy transistor, you will be lucky to get enough current to power the LED at 8mA. Use a 2N4401 or the BC337. Or if you want to get a lot more current, try the 2SD965 or NTE11. If you can get some disposable flash cameras from your neighborhood drugstore or photo shop, the flash inverter uses this kind of transistor, and makes a great source for free transistors.

The above circuit is okay, but since the LED _is_ a diode, you don't need the D2 and C2 filter cap, just connect the LED across the emitter and collector. And R1 will have to be lower, probably 1k, if you use something better than the 2N3904. The 2N3904 won't cut it with even a

470, it'll just get hot and poof. And whatthe hell is R2 there for? That's just wasting power and ruining the efficiency!
Reply to
Watson A.Name - "Watt Sun, th

I'm actually using one and it's pretty decent on a white LED. If you have to despise me for it, I guess I can only hope to make it up some time later on. (I'm just a modest hobbyist, so I take corrections from just about anyone.)

Fair enough.

Actually, that's what I did before. In fact, I had no R2, as well. I just added those for tinkering, at some point, to smooth the pulses through the LED.

Yes, I started out just as you say. Works just fine. This is what I'd started with:

V+ V+ V+ | | | | | | | )|. .|( (about 50" of | )| |( magnet wire | )| T1 |( for both | + )| |( windings) --- | | - B1 | | --- \ +---------, - / R1 | | | \ | | | / | | | | |/c Q1 --- ~ | '------| NPN \ / ~ | |>e --- LED | (B1 > 1V) | | | | | gnd gnd gnd (can be connected to V+, as well)

Threading up the transformer on a tiny toroid is dead easy, too. By the way, I've picked up some small packages of them from a local electronics supply house, but I've not found a good web site that has them. Do you know of a good source for various ferrite toroids?

Jon

Reply to
Jonathan Kirwan

Excellent tip.

If the reason we use ASCII Schematics is because of the text based USENET. Then why do some websites still use ASCII Schematics?

Reply to
Tim Zimmerman

Leftover source material from the days of telnet perhaps...

Reply to
Lord Garth

Because if it works, don't fix it!

Cheers! Rich

Reply to
Rich Grise

Italians with groups like this on their local ones like it.hobby.elettronica use interesting program to draw & see schematics for posting in text only usenet IMHO much bettter than ASCII ...

its FidoCAD (maybe someone could write to the author to make an English interface & help file for it). Can be found here: less than

1Mb installed:
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you draw a standard schematic, export it as text & paste it into a message like this (pasted code) interesting oscillator:

[FIDOCAD] MC 85 45 0 0 580 MC 70 45 1 0 170 MC 50 55 0 0 170 MC 50 45 0 0 120 LI 85 45 60 45 LI 60 55 85 55 LI 50 45 45 45 LI 45 45 45 55 LI 45 55 50 55 MC 45 65 0 0 045 LI 45 65 45 55 LI 100 45 100 25 LI 100 55 100 75 MC 100 25 3 0 010 MC 100 75 1 0 020 TY 105 15 5 3 0 0 0 * +6V TY 105 80 5 3 0 0 0 * -6V MC 105 30 0 0 170 MC 105 65 0 0 170 MC 120 30 0 0 045 MC 120 65 0 0 045 LI 105 30 100 30 LI 120 30 115 30 LI 105 65 100 65 LI 120 65 115 65 LI 110 50 135 50 MC 140 50 0 0 075 MC 145 50 0 1 075 TY 60 60 5 3 0 0 0 * 2x 47nF TY 45 35 5 3 0 0 0 * 1mH TY 115 60 5 3 0 0 0 * 100n TY 115 25 5 3 0 0 0 * 100n TY 155 45 5 3 0 0 0 * 34kHz TY 75 35 5 3 0 0 0 * LM6181

You to see it with that installed program, just copy that upper complete code, open the program, from menu open: modifica/incolla/come nuovo documento .... & so you see the schematics like usuall one; IMHO not a bad trick ... & easier than ASCII pics schematics ...

Try it 4 fun ...

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Spajky

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