Monday, January 11, 2016

Project SSTC2 - Part 2 (Just a quick update - more to come)

Current issues that I'm addressing (to finish this coil).  I want to do it right so I'm trying not to rush it (even though I want to - just so I can have it done).
  • rewinding secondary coil (DONE)
    • My initial coil I ruined when I tried removing some inclusions trapped in the resin coat I applied - ended up pulling and breaking one winding.
    • Decided to completely rewind new coil (wanted it to look good)
      • made a winding rig and cut winding time in half
  • Question regarding capacitor on MOSFET gate drive chip in Guangyan's schematic
    • The datasheet for the UCC27425 and schematic differ.  Page 10 of the datasheet recommends 
      • "two VDD bypass capacitors are recommended to prevent noise problems. The use of surface mount components is highly recommended. A 0.1-μF ceramic capacitor should be located closest to the VDD to ground connection. In addition, a larger capacitor (such as 1-μF) with relatively low ESR should be connected in parallel, to help deliver the high current peaks to the load."
  • Primary Side of coil
    • voltage double (DONE)
      • difficulty finding capacitors that I could pull from older scrap
      • ended up breaking down and ordering them
    • Concerned about minimizing stray inductance in half bridge (DONE)
      • etching/making multi layer pcb (unable to)
      • make connections with copper sheet/plate
        • unable to solder to wider or thicker copper
          • heat conductivity of copper so high that entire area would need to be heated enough to melt and bond solder which would require higher temps for a longer period of time (would end up killing sensitive components).
      • compromised by using narrower copper sheet/plate
  • Want to get an actual measure of the resonant frequency of my secondary coil
    • Need to finish making a working Frequency/signal generator (DONE)
      • AD9850 working - set up to scan from 100kHz to 200kHz (as a start, each second frequency increases by 1kHz) - Yes I'll be posting an update to my AD9850 Signal Generator Project.
  • Finish making a nicer looking Topload for Secondary Coil
    • Not an immediate concern - I do have Topload's I can use for testing
  •  Make shielded enclosure for electronics
  • Add optical connection for external interrupter
    • Also not an immediate concern - more something to add after all is working reliably.
SSTC2 part 1