Sunday, December 18, 2011

Started Soldering Mike's PSIs

"Started Soldering Mike's PSIs," now there's an odd title for a blog posting. What could that possibly mean?

It means the world has gone topsy-turvy. Rather than Mike Senna helping me build my droid, I am lending a hand to put the finishing touches on his droid #2. Mike never did finish the electronics for the dome on his second droid, so while he's busy with WALL•E and another project, I'm helping with the electronics for his second dome.

Mike mentioned that he has Scott Gray's JEDI system for the front and rear logics, but he does not have any PSI circuits. I ordered a couple of my favorite blinking light kits from, and got to work on them this afternoon.

Part-by-part, I started soldering them up.

I had to stop at about the half-way point, as I plan to swap out the LEDs, capacitors, and two of the four resistors on each board. This will allow for brighter LEDs. I want to wait until I have the LEDs in hand before continuing, but that shouldn't be long.


alanrw said...

Hi Victor, it looks like Allelectronics changed the circuit design with variable resistor? Can you state the specs on the changes you made to the stock design?

Best wishes to you and Mike (and families) for the holidays.


Victor Franco said...


The circuit has always had a variable resistor/trim potentiometer, but it looks like they changed the actual part for an equivalent.

Here are the part swap details for the front PSI, I am copying what I did in my October 10, 2010 entry:

"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...

...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."

I purchased my NTE brand LEDs at Orvac Electronics in Fullerton, CA.

I haven't been able to find the exact same LEDs for the rear PSI that I used in my droid, but once I've got some suitable replacements, I'll post the changes for the rear PSI as well.