~ Basic Info ~
This page describes my SMT (Surface Mount) implementation of the HCFR Colorimeter. This is repackaging of the DIY design posted by the HCFR group HERE. The gerbers for PCB fabrication and Bill of Materials for this surface mount design are available. GERBERS BOM.
In addition to a change to SMT (0603) size components, other deviations from the HCFR design include moving the sensors closer together and rotating one of them 90 deg. I also have omitted all the parts for the IR transmitter (used by the HCFR application to talk to a set-top DVD player when using the HCFR pal DVD) but I have included footprints and connectivity for it. The board should support it if you chose to add those components yourself.
The PIC is programmed in-circuit via a 5-pin ICSP connection @ J2. The connectivity (schematic) of the USB, PIC, and sensors, is the same as the HCFR DIY design as is the PIC program. (The remaining non-populated circuitry on the board is for a totally non-related project that I stuck in to take advantage of the small PCB fabrication. It can be ignored.)
~ Calibration Files Info ~
Presently, the HCFR based sensor and application uses a calibration profile (sensor conversion matrix coefficients) for each display it is to be used with. If this is your first or only colormeter, the HCFR application (and website) includes many pre-made probe calibration profiles for various displays. The very low unit-to-unit variation of the TAOS photo diode array affords a method of creating a conversion matrix based on the spectrum characteristics of a display rather than an individual colormeter.
Alternately and perhaps ideally, the probe / app can to be trained to a known D65 reference (after you’ve used a different probe to establish a D65 white point) and a custom calibration file created.
To create a new calibration file, a short probe calibration routine is performed at first use where a D65 white field and the component colors (RGB) will be presented to the probe. The offset coefficients for the sensor conversion matrix will be calculated and a calibration file will be created specific to that display. This only needs to be done once per display.
The absolute ‘accuracy’ of the probe will depend on the calibration file and the accuracy of the reference instrumentation used to verify that. As I used a SpyderII to set my reference for my HCFR probe calibration, it won’t be anymore ‘accurate’ than the SpyderII it was trained against. Although it can’t be anymore accurate than the reference, it can perhaps track better or have a better range, better resolution or other benefits relative to the reference meter.
The nearest specs I could surmise would come from the TAOS TCS230 filtered photo diode array datasheet HERE and app note HERE.
It has been suggested by the HCFR developers that the need for a HCFR probe calibration file may not be necessary and are exploring methods of eliminating it. A document further discussing HCFR calibration files can be found HERE.
~ Extra Items for Sale ~As the bulk of the cost, effort and hassle factor for such a DIY project is high for only a single unit, I decided to contract a few better quality boards and build a small batch of sensors and offer the extras for sale to the community.
I am offering the following two items for sale:
~ #1 ~An assembled, programmed and tested unit in plastic box, as shown at left.
$77.00 USD including priority S/H. (US only) If you desire a complete kit of parts, this completed unit can suffice. Just carefully remove all the components and then carefully resolder them. :-)
*NOTE: You’ll need to supply your own USB cable to the sensor (Type A-B) and obtain the driver (.inf file) from the HCFR DIY page HERE. The sensor is powered via USB. (<100mW.) The PIC is programmed with the 5.1 hex file from the HCFR DIY page HERE.
~ #2 ~Raw unstuffed PCB. 2 layer with soldermasks and topside silkscreen, as shown at left. 1.5" x 2.0"
$20.00 USD including priority S/H. (US only)
*NOTE: I messed up the footprint for J3, the USB connector, so the part called out in the BOM needs to have it's legs bent a little to get it to fit. I fixed it in the gerbers that I posted.
~ Payment and Shipping Info ~Payments to be made via PayPal (no cost to buyer). Please be sure to include your shipping address.
Shipments will be made within two days after receipt of confirmed PayPal pmt. (4-6 days for E-checks)
If interested, please contact me via EMAIL for availabily inquires and PayPal info.
~ RoHS Rambling ~
*NOTE*: Both the blank PCB and the assembled board contain solder. Most solders (good ones) generally contain lead. Lead is toxic when ingested in sufficient quantities. Please avoid grinding these up and eating them. These products likely contain lead (Pb) and are NOT certified RoHS compliant. They are intended for the DIY hobbyist and for experimental research. For more information (actual science) on RoHS, Pb in electronics, and the environmental impact, I can suggest starting HERE.