[sac-forum] Re: Red LED Lamp Project Questions
- From: "Jimmy Ray" <jimmy_ray@xxxxxxx>
- To: <sac-forum@xxxxxxxxxxxxx>
- Date: Mon, 18 Feb 2008 19:28:41 -0700
LED's negative lead is SHORTER! (Sorry)
From: sac-forum-bounce@xxxxxxxxxxxxx [mailto:sac-forum-bounce@xxxxxxxxxxxxx]
On Behalf Of Jimmy Ray
Sent: Monday, February 18, 2008 7:26 PM
To: sac-forum@xxxxxxxxxxxxx
Subject: [sac-forum] Re: Red LED Lamp Project Questions
Hi Fran,
While it may be a bit off topic for this discussion group, I will continue
for the benefit of the curious and those who may want to built this fine
piece of astronomical support gear. We'll take it off line if it becomes an
issue.
Question 1: the diodes go in the base. One attaches to one of the "output"
leads of the transformer (which now makes it the "positive" lead for this
project) and the other on the "positive" lead of the 12v input jack on the
base (Center terminal). Make sure to insulate these with heat shrink
insulation or such to prevent a short. Positive polarity goes to pin three
of the LM317 power regulator, Negative goes to the Potentiometer. The
diodes prevent a "reverse" flow of power back through the transformer or
your battery (bad if they both happen to be plugged in).
Question 2: You will need to work very closely with Andrew's schematic. The
hint here is just because two lines cross doesn't mean there is a
connection. Only where the lines come together in a "dot" (red in the case
of this schematic) is a connection made. If you lay out the components on
the board close to what he shows you can then bend the leads of the
components to be connected over each other and solder them. You need to
watch closely the polarity of all components, except the resistors. LED's
negative lead is the one which is longer and the bulb base has a "flat" on
that side. Watch out as well for the polarity on the capacitor. Hook it up
backwards and you will hear a loud "pop" followed by smoke just seconds
after initial power up (replacing it with a new one should fix this if you
do).
Bonus Question: Not really. For me it made a "cleaner" installation. Yes, it
would take two boards to do it.
Have fun,
Jimmy Ray
From: sac-forum-bounce@xxxxxxxxxxxxx [mailto:sac-forum-bounce@xxxxxxxxxxxxx]
On Behalf Of Fran
Sent: Monday, February 18, 2008 2:32 PM
To: sac-forum@xxxxxxxxxxxxx
Subject: [sac-forum] Re: Red LED Lamp Project Questions
Thanks Jimmy,
I have 2 basic problems right off the top.
1) There are 2 diodes shown on the diagram - they seem to be between
the 2 potential power sources and the board. They don't show up on the pix
of the board. Where do they go? For that matter, where does power come
into the board?
2) I can't seem to figure out from the diagram and the pix of the back
of the board, just what is connected to what and which way the LEDs should
be oriented.
3) Bonus question: Is there any advantage to trying to put the
components in the base? If so, does that take another board then?
It is my hope to make 3 of these, because I have a couple of friends I'd
like to give them to as gifts. I have the components for all 3, but I'd
need to get more circuit boards.
Thanks again,
Fran
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