Illuminated ep question

Hi all, I have just gotten hold of the meade 9mm illuminated EP. It was a
steal so bought it. Its the corded version which would normally be
fed from the LX200 base. I have just read that someone managed to
blow the LEDs by using the AUX output on an LX50. I intend to run it
using a battery set-up on any portable scope. Anyone out
there use this thing like this or could pass on the electrical spec,
voltage/current requirements. Would be much in your debt!

Cheers, Eddie.

I believe the maximum voltage is 3V. A simple battery pack with a means to vary the voltage would do. I think Radio Shack sells a cigarette lighter adapter with the appropriate requirements.

Lee

Most of these red LEDs are spec'd around 30mA
current and 1.6v forward drop. You can just get an
appropriate resistor at Radio Shack and rig-up
a cord with the resistor in the circuit to
limit the current to 30mA or less, and you should
be fine. I've got the polar scope on my G11
hooked up this way; I run it off the 12v output
on the drive box.

So if you've got a 12v source you need a
12v/0.030A = 400 ohm resistor. If its 18v then
you need about 18v/0.030A = 600 ohms. A 1/8 or
1/4 watt carbon-type resistor is what you want.
If you can't get these exact ohm values, get the next
larger value (i.e. 470 ohm instead of 400 ohm).

If you want to get fancy, you can also get a
5000 or 10000 ohm variable resistor
(potentiometer) and put it in the circuit, too,
and you'll have a dimmer.

These LEDs are polarity sensitive -- you'll only get
light out if the + is connected to the +; so you
may want to check you've got it the right way around
before making the final connections. Nothing bad
will happen if its backwards; there just won't be
any light until you fix it.