Building a case for the
Programmable Voltage Reference project.
While waiting on the version 2.12 printed circuit boards from OSH Park, I decided to do some work on the case.
For consistency I ended up using the same model of Hammond enclosure that was used in several previous projects. The model 1455N1601 enclosure measures 6.3″ L x 4.055″ W x 2.087″ H (160 x 103 x 53mm) and is made from extruded aluminum. The main body is an U shaped extrusion with a flat extrusion forming the top. The unit comes with 1.5mm aluminum end plates, with a black plastic bezel that covers the joint between the two aluminum pieces.
I ordered a custom front panel from Front Panel Express in the medium bronze anodized aluminum, with a thickness of 2.5mm and an outer bevel of 1mm so that it would match the original 1.5mm panel depth of the plastic bezel.
The original Programmable Voltage Reference by uChip used a very small 4 digit 7 segment HP bubble display and a rotary encoder mounted on the board. The V2.12 board will have a remote display, and a header for a RGB LED rotary encoder.
My plan is to modify the aluminum knob with a center light pipe to provide a status indication of the current mode or error condition.
I ended up with a bunch of blue 4 digit 7 segment LED displays from a recent Sparkfun sale. It should be real easy to see the current voltage setting on the panel from across the room with these!
I put together an I2C interface board for these displays based on a design by Adafruit, using a Holtek HT16K33 RAM Mapping 16*8 LED Controller Driver chip. A nice feature of this chip is a dimming command that provides display dimming in 1/16 increments. I am thinking of utilizing this feature for saving battery power after a set time, and have the display resume normal brightness after the rotary encoder has been moved, or it’s push button pressed.
I made a bunch of these boards and will most likely use them in future projects.
The Programmable Voltage Reference case is mostly ready, and I am now waiting for the main board to arrive in the next few days. I will document the build and post the final results in the near future.