J
James Sweet
- Jan 1, 1970
- 0
I reverse engineered a couple more electronic ballasts I came across
recently. Both are from those cheap Lights of America outdoor dusk till
dawn wall lights. The first uses a 42W Fluorex compact fluorescent lamp
which has an ordinary medium screw base but that contains only the
resonant capacitor. The second uses a 50W high pressure sodium lamp.
Both are nearly identical circuits, differing primarily in the DC rail
voltage and the inductance of the resonant choke, both varieties appear
to be wound on identical cores approximately 1" square. They are a
series resonant half bridge design based around the UB2021P ballast IC.
Both also use a rather unusual arrangement of two transistors to
construct an SCR rather than using a real SCR. Must have been a few
pennies cheaper I guess. Both ballasts had one or more shorted mylar
capacitors, the HPS one I revived, the fluorescent one suffered a
catastrophic failure that took out nearly every semiconductor on the board.
Fluorescent:
http://picasaweb.google.com/lh/photo/jQQZ8jdXim_H3oXXErgMkw?feat=directlink
HPS
http://picasaweb.google.com/lh/photo/EMW1Bdel8IBKLqQyk2eGzQ?feat=directlink
recently. Both are from those cheap Lights of America outdoor dusk till
dawn wall lights. The first uses a 42W Fluorex compact fluorescent lamp
which has an ordinary medium screw base but that contains only the
resonant capacitor. The second uses a 50W high pressure sodium lamp.
Both are nearly identical circuits, differing primarily in the DC rail
voltage and the inductance of the resonant choke, both varieties appear
to be wound on identical cores approximately 1" square. They are a
series resonant half bridge design based around the UB2021P ballast IC.
Both also use a rather unusual arrangement of two transistors to
construct an SCR rather than using a real SCR. Must have been a few
pennies cheaper I guess. Both ballasts had one or more shorted mylar
capacitors, the HPS one I revived, the fluorescent one suffered a
catastrophic failure that took out nearly every semiconductor on the board.
Fluorescent:
http://picasaweb.google.com/lh/photo/jQQZ8jdXim_H3oXXErgMkw?feat=directlink
HPS
http://picasaweb.google.com/lh/photo/EMW1Bdel8IBKLqQyk2eGzQ?feat=directlink
