The Cyber-Spy.Com Usenet Archive Feeds Directly From The Open And Publicly Available Newsgroup Sci.Electronics.Design
This Group And Thousands Of Others Are Available On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic, Opinions Or Content Posted To This Or Any Other Newsgroup. This Web Archive Of The Newsgroup And Posts Are For Informational Purposes Only.
From: Ian Stirling
Newsgroups: sci.electronics.basics,sci.electronics.design
Subject: Re: How to make/solder a circuit fast?
Date: Sat, 14 Sep 2002 15:24:55 +0000 (UTC)
Message-ID:
References: <3d816727.129136963@news.pacific.net.sg> <3d820e45.171925720@news.pacific.net.sg>
NNTP-Posting-Host: mauve.demon.co.uk
NNTP-Posting-Date: Sat, 14 Sep 2002 15:24:55 +0000 (UTC)
Originator: root@mauve.demon.co.uk
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"
> wrote:
>>Give your friends some basic soldering training...
> *laff*
> 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?
Yes.
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
much easier.
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:inquisitor@i.am | Ian Stirling.
---------------------------+-------------------------+--------------------------
What a wonderfull world it is that has girls in it! -- Robert A Heinlein.
Go Back To The Cyber-Spy.Com Usenet Web Archive Index Of The sci.electronics.design Newsgroup
|