Some time ago I was developing a medical instrument which required histogramming, which got me in the mood to retake my own PIC MCA project(http://home.comcast.net/~prutchi/index_files/scint.htm ). I used the variable RAM in the microcontroller (16F877), so I limited the number of channels to 95 and let the histogram run until some channel reaches 240 counts (the highest 8-bit number that yields an integer when divided by 8). The firmware then displays the spectrum as a bar with a maximum height of 30 pixels for each one of the 95 channels.
Click here for complete how-to construction instructions in pdf format.
Click here for a pdf of the schematic diagram for the front-end of the MCA
Dr. Prutchi:
I was lucky enough to purchase a RAP47. Instead of just making another counter, I started to wonder whether I should try making a simple MCA. I remembered that you had posted an article a while back. I tried to find updates but I wasn’t able to locate any.I am comfortable with analog design, but software is my weak point. In your article for your MCA using a 16F877, it mentioned that the hw was: The MCA hardware portion of the instrument is a peak detector and track/hold that feeds
the PIC’s A/D. The design is heavily based on:P.-H. Lefebvre, M. Clar, H.-P. Garnir, =A1=C8DESIGN OF A NETWORKED MULTICHANNEL ANALYZER (nMCA)A1C9, International Conference on
Accelerator and Large Experimental Physics Control Systems, 1999, Trieste, Italy
However, I was not able to locate a schematic, if you would be so kind as to post the schematic of both the analog and digital portions it would be greatly appreciated. If it is already posted somewhere, can you tell me the appropriate urls ?
Sincerely
Peter( newbie)
Hi Peter,
The schematic for the LABX1 is at: http://melabs.com/downloads/labx1sch.pdf
The most up-to-date schematic for the S/H and logic is mentioned in the post at: http://www.diyphysics.com/wp-content/uploads/2012/02/mca-schematic.pdf
Before developing a hardware-based MCA, please consider the following option: http://www.diyphysics.com/2012/09/21/using-the-79-sainsmart-dso201-pocket-oscilloscope-and-gammagrapher-with-the-pmtscintillation-probe/
Cheers,
David