Re: [CAD_CAM_EDM_DRO] Re: Two Lamps?

On Dec 14, 2004, at 1:40 PM, Torsten wrote:

>>>
>>> On the first attempt I learned that a Led dose
>>> not work with DC current.
>>>

Leds (light emitting diodes) most assuredly work with DC. In fact,
while it would be an odd design choice, you could use leds to rectify
AC and convert it to DC. An led, like other diodes, has two terminals,
an anode(+) and a cathode(-). Here is a simple tutorial you may find
helpful <http://www.theledlight.com/ledcircuits.html>. You would need
a resistor in series with the led. The value would be calculated using
ohms law (e=ir), based on the voltage and current ratings of the led
you are trying to use. If you decide you want to use an led and aren't
sure of how to size the resistor let me know, I'll be glad to figure it
for you.

If you want to stay with using the lamps that would be fine, but
instead of using two lamps, just use a dropping resistor in series with
it. If you were to use a 1k (1000) ohm resistor, current would be
limited to .027 amps. 1K is a standard value, readily available at
Radio Shack or Fry's. I believe that you would get adequate
brightness, and much longer bulb life. If that isn't bright enough for
you, you can go with something a little smaller, but anything less than
675 ohms will begin to exceed the maximum ratings for the lamp - it
will get brighter, but die sooner. The resistor should be rated for 1
watt. If you can't find a 1 watt in the right value, then you can
parallel 2 1/2 watt resistors, but you must double the resistance value
(i.e. Qty.(2) 2k 1/2 watt resistors in parallel = Qty.(1) 1k 1 watt
resistor)