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From: Ian Stirling
Subject: Re: How to make/solder a circuit fast?
Date: Sat, 14 Sep 2002 15:24:55 +0000 (UTC)
References: <firstname.lastname@example.org> <email@example.com>
NNTP-Posting-Date: Sat, 14 Sep 2002 15:24:55 +0000 (UTC)
User-Agent: tin/1.5.6-20000803 ("Dust") (UNIX) (Linux/2.4.18 (i686))
The little lost angel wrote:
> On Fri, 13 Sep 2002 07:13:31 -0400, "gagir"
>>Give your friends some basic soldering training...
> It's a very simple circuit (only 10 parts, 3 of which are just
> connectors) which they could have learnt to make if they really wanted
> to... and not let a woman do what's tradditionally a man's job.
Actually, women are more common in electronics assembly.
> BTW, is there anything wrong with the following?
> The widget's for them to put fancy lights on their new fangled acrylic
> fans for their PC. Would the different forward drop of super bright
> LED of Red, Blue, Green differ too much to make it a worry?
Red can have a voltage of down to about 1.6V, Blue LEDs can be closer
to 4V (all at 20ma)
> The reason for having L2 separate is I need something like 16mA to get
> a brightness that's not too much diff from 20mA. If I put three
> together, two blows and the one remaining won't have much chance of
> surviving 48mA rite?
I'd say you'r going way too complex, if the device is in a PC, it's
You have a regulated 12V supply available, there is absolutely no
point in putting in another regulator.
I'd go with something really, really simple, like simply connecting
a resistor in series with each LED socket to +12V, and the other side
of the sockets to 0V.
The resistors should be around 12V/.02A, or 600 ohms, maybe a bit less.
If they are 600 ohms, then when the LED is shorted they'll dissapate
under a quarter of a watt each.
This has the slight problem that it may blow some sensitive LEDs with the
12V reverse bias if the LEDs are plugged in backwards.
Connecting a 4V zener across each diode is one way.
Connecting a small signal diode to a common zener is another.
I think that connecting signal diodes to the 5V line is probably a bad
idea, in some (rare) circumstances that could cause problems.
http://inquisitor.i.am/ | mailto:firstname.lastname@example.org | Ian Stirling.
What a wonderfull world it is that has girls in it! -- Robert A Heinlein.
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