Pboard Project Pboard (short for "P-channel board") is the working nickname of a new driver board that I plan to use with the next version RLbC. Whereas RLbC 2 only featured output relays, Pboard will make use of Adafruit's PCA9853 based servo-driver board to provide PWM signals to the outputs via P-channel MOSFETS. Doing so will allow for fading the lights. Why use P-channel Mosfets? I chose to use FQP27P06 P-channel MOSFETS over the more commonly accepted easier to wire N-channel logic-level MOSFETS out there simply because I wanted high-side switching. Call me weird or old-fashioned, but I have always designed my low-level voltage systems with Common tied to the "negative" side of a supply (split or dual-tap not withstanding). However, going to P-channel switching does make the design a little more complex. Buffering is required since I can not directly tie the output of a PCA9685 to Vss (12VDC) otherwise it will be damaged....
One thing I had to add was a power-up RESET circuit, which is just a 10uF cap and 1K resistor in series across the 5v supply. The RESET pin on the counters are connected to where the resistor and cap meet so that at power up, the cap is effectively a short to 5+. This causes a logic HI on the RESET lines to set the counters to zero. After the capacitor has charged up, it no longer looks like a short to 5+, so the only path left is through the resistor back to ground. That presents a logic LOW on the RESET pin, which allows the counter to count up or down.
This is the second version of my Remote Lightbox Controller (RLbC) made from parts from the controller from last year. This new version is cleaner and simpler. At the top is the power supply for the box. It's complete overkill at 15VDC@30A, but heck it was only $24 off of ebay. In the lower right is your typical XBee +shield on top of an Arduino Uno (Rev2). To the lower left is a SainSmart 8 channel relay board whose logic-side components are powered by the little green 5VDC power supply. Yes, I might've gone with a buck/boost convertor, but since I already had the 5VDC kit I used it. Another view of the control box. Here you can see the wiring that connects the output jacks to the channel relays. Lid closed, lamp cables plugged in. The lamp cables are 25+feet long with standard 1/4" mono plugs at each end. Test arrangement. At this point, I'm able to transmit control signals wirel...
Comments