Saturday, May 08, 2010

More PSI LED Tests

Today I went to Orvac in Fullerton, CA, and purchased a bunch of LEDs (and other components) in an attempt to get a brighter PSI display working.

First, I tested a couple of 10mm 1200mcd blue LEDs on some project board to see how they looked.

Then I took a look at them in the dome. This was with the flash on. They seem reasonably bright.

Next, I tested three 5mm 3500mcd red LEDs on the project board.

Even though they are rated to be brighter, they don't seem quite as bright as the blue LEDs. I tried them in the dome, this is with the flash off. For those dying to analyze the situation, the supply voltage is 9 volts, Vf=2.5V, If=25mA. I am using a 60 ohm resistor.

Feeling industrious, I decided to try wiring up my own flasher circuit on the project board, just for the exercise.

Even though I believe I followed the schematic, the circuit didn't work, the LEDs did not illuminate. I got too tired to troubleshoot it tonight, maybe tomorrow or during the week I'll take another look at it. It's possible that my potentiometers or transistors are not to spec.


Russell said...

Hi Victor!

Did you know some colors react better with out eyes than others? Green and Blue are naturally more stimulating to our eyes than red so they will appear brighter.
Maybe try a much brighter red LED then the blue to balance the effect, blue being brighter to our eyes than red.

I know from my astronomy hobby that green is very bright to our eyes. I use a green laser pointer to point out stars to people up at the Griffith Observatory during our star party nights.

Russell said...


Not "without out eyes" hahah!

Victor Franco said...

Thanks Russell. I'll monkey around with what I have on hand, and if necessary, go find some even brighter LEDs.