[wwest]

Originally Posted by syzygy

We seem to have gotten a bit off track...



First off, the lighting on your clock looks pretty damn good - nice and even and well distributed. I do have a couple questions (and assumptions).

Just so I'm clear on what you did with this, you mounted your 1W strawhat LED in a BA7 base from which you removed the bulb, externally wired in your 3W resistor and diode. Is that correct?

No diode since it's not possible to reverse bias the LED.

-Having the resistor in the base creates too much heat (at the .2 A rating) and fries the LED. Having the resistor outside the base is sufficient to allow heat dissipation?

Yes. Plus there plain is not enough room inside the BA7 base to accommodate a 3W resistor. The resistor is mounted in series with the BA7 socket, outside the case.

-I figure you're likely using a 47 ohm resistor? Would using a higher than 3W resistor, like a 5W, gain anything? More resistant to heat?

56 ohms. A three watt resistor is the minimum wattage REQUIRED, the resistors I used may have very well been, probably are, 5W. The resistor is encased in shrink wrap as are, separately, the wire leads/connections

-How much difference in light output between 100, 200 and 300 mA?

Surprisingly, not much, not between 300mA and 200mA anyway. 100mA remains to be seen. I chose 200mA primarily as a result of the free air failure rate at 300mA that I observed.

-How far extended from the base did you mount the LED? Obviously one is limited by the amount of space inside the gauge, but would you want it out as far as possible?

Virtually zero, I had to modify the larger LED lead to do that, yet another reason for derating to 200mA. Some of the guages have the incandescent bulb's glass encapsulation right up against the forward travel limit so I had to match that, and no more, with the LEDs.

I seem to remember that somewhere on the INTERNET, Porsche forum most likely, I posted a picture of the completed Ba7 LED bulb assembly, the component parts, etc. Can't find it on the INTERNET nor in my picture archives.