Saturday, October 23, 2010

Soldered Together PSI Circuits

I finally had a chance to go LED shopping today, so I was able to solder together the Processor Status Indicator circuits tonight.

Here is the pile of parts.

I really love this flasher kit. It is from Velleman, model #MK102. It is readily available at many on-line electronics outlets, usually for under $5.00. Buying the parts separately at Radio Shack would cost more. The blink speed is adjustable. The instructions are pretty simple.

For the front PSI, I'm substituting some of the parts with other parts, as I did with droid #1, in order to get brighter blue and red LEDs to work. Specifically, I'm substituting the 1-Kohm resistor that goes on the red LED with a 62-ohm resistor. I'm substituting the 1-Kohm resistor for the blue LED with a 39-ohm resistor. Finally, I'm replacing both 10-µfarad capacitors with 100-µfarad capacitors, to achieve the right blink rate with the trim potentiometers. I'll get to the replacement LEDs shortly.

This clipping tool comes in handy for cutting the leads off after soldering.

For the red LEDs, I'm using three red LEDs with the following specs: 5mm, 3500mcd, 25 milliamps, 2.5 forward volts, NTE part #NTE30041. I soldered these in series, anode to cathode.

For the blue LEDs, I'm using two blue LEDs with the following specs: 10mm, 1200mcd, 25 milliamps, 4.0 forward volts, NTE part #NTE30070. I soldered the pair in series, anode to cathode.

Time to power it up! Will it work? Will it blow up? Will it do nothing?

It works!

For the rear PSI, I'm using the Velleman kit as-is, without part substitutions, so I soldered up a second board. For whatever reason, I get decent brightness with the green and yellow LEDs I'm using.

Actually, I wasn't so happy with the yellow LED that I used at first, so I dug up an ultra-bright yellow LED and gave that a try.

Looks good!

Green is looking good too.

Finally, a family portrait of all the dome parts that will light up, minus the front holoprojector. The front logics are still in the dome from when I was fitting them in place, and I powered up the rear logics for the occasion.

I still need to set up the wiring to the terminals, prep the switches, add PSI diffusion, and mount the resin eye, not to mention tape the dome panels in place. Still, it's getting there.

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