Camera and Telemetry Boards Assembled

I was delayed in assembling the camera board because I ordered the wrong power jack: the parts list specified a PCB mount jack from SparkFun, but I was placing a large order from DigiKey so it made sense to find an equivalent part there. Unfortunately there are many, many similar jacks available. I ended up ordering one (well, probably 20) with eyelet connectors rather than through-hole pins for PCB mounting. Sigh. I realized the problem as soon as I tried using the jack, then ordered the parts from SparkFun. By the time they arrived -- I didn't pay for express shipping, which would have almost doubled the price -- I'd finished the rest of the board and could just add them in.

I then moved on to the telemetry board; it connects via USB to the controlling PC and via a ribbon cable to the power board, and provides the control software (POCS) on the PC with the ability to switch power on-and-off for various components, and to measure current, temperature and humidity.

The original board layout called for a very awkward assembly step: soldering wires to the little stubs of pins poking through the board from the ribbon cable IDC header. The design choice was necessitated by the spacing of the pins on the header (2 rows of 0.1" spaced pins) and the choice of a breadboard-like circuit board as the base of the design. A normal breadboard has no spot for such a grid of pins, unless it is OK to short out adjacent pins (either in a row or a column). The design called for using an Adafruit Perma-Proto Mint Tin Size Breadboard PCB. It has a group of holes at each end of the board that are not connected to their neighbors in to which we could place the header.

Assembling this is not only challenging to execute, but I was worried that the connection would be fragile. I was very relieved when I found that Technological Arts in Canada sells a breadboard adapter for the IDC header. Based on that, I sketched out a new layout for the same schematic... well, I did change the power supply to the DS18B20 temperature sensors, which I tested on a breadboard before assembly.

Here are the results of both builds, with the telemetry board on top, the camera board below:

I rushed the layout of the telemetry board, so the layout isn't as clean as it could be. For example, I forgot that the incoming power is DC 12V, so can't be supplied to most of the components, as they require DC 5V. As a result, the power jack is at the top left of the board, adjacent to the power rail I planned to use for 5V.


Popular Posts