First design revision, sneak preview

A project log for JJ Tricoder

Goal of this project is to develop functional Tricoder device, similar to type TR-580.

jaromirsukubajaromir.sukuba 04/21/2014 at 15:530 Comments

The JJ Tricorder (JJTC) projects seems to be stalled, however we worked hard on it, doing mostly the invisible work, like finding the components, sensors, choosing development tools and listing the final project goals, but I have PCB layout done.

Because JJTC revolves around sensors and processing the output of the same, this is key decision. Sensors will be grouped in three gropus :
- Analog sensors. There are four sensors in this group - sensor of sound (microcphone), magnetic field (inductor), light in visible and invisible (near infrared) spectrum. Output from those sensors will be routed through amplifier, presumably with selectable gain into analog input of MCU, allowing to display waveform and frequency spectrum of incoming signal. Analog bandwidth of this part will be ~ 20kHz, allowing inspection of whole audible spectrum.
Unfortunately, the near IR sensor will work upto ~1000nm of light wavelength, because it is silicon part, unable to detect higher wavelengths. Higher part of spectra, in 1000-5000nm, covers heat sources, for example. IR diodes for this part of spectrum are usually quite expensive, as it is made in low volume and from more exotic semiconductor materials.
- Digital sensors. There are five sensors in this group - sensors of temperature, humidity, accleration, magnetic field and atmospheric pressure. Sensors will share common I2C bus, with much narrower bandwidth, so that results will be displayed in numerical format or in history graph.
- Impulse sensor. There is only one planned - Geiger-Muealler tube. Voltage converter to approximately 400V is needed, adding another design challenge.

Stay tuned. Julia is working on design of JJTC case, I finished PCB design and PCBs are in the production, hoping on tomorrow delivery. There is a small surprise in the final design, uncommon in most of the hobby designs. Components are already on my table, so I can start populating the PCB as soon as the it arrives.
I expect major update on this project on tomorrow.