Here's another one but this time it's Induction. Either Sylvania's Icetrons or Philips QLs.
#4 - Possible induction lamps inside Costco's freezers. Will try and confirm whether they're induction and whose brand. Light from inside the freezer look kinda weird to me, dunno why they look weird to me. (Not the High Outputs at door edge but inside where they re-stock the freezers inside so the older products will be at front while newer will be at the back.)
Could easily be fluorescents
#5 - Possible induction lamps at a local park. There is a bunch of acorn fixtures carrying white light (Nice either way!) They look too diffused and softer than MHs. I will try and see whether the lamps pulses when looked through the camera. If not, induction QLs. If it does then they're coated MHs. (Unknown if the makes electronic ballasts for acorn fixtures.)
All electronic ballasts do not pulse much in the camera, while all might still pulse a bit, including supply units for induction lamps. The extent of the pulsing is given by the filtering properties in the mains rectifier - the front end part of any electronic unit (convert mains AC to intermediate DC bus, sometimes it include PFC stage) and by the presence of following main current regulating principle.
This rectification yield some ripple to the bus.
In the case of HF or induction lamps, whose are ballasted by some impedance (on electrode lamps ths is usually an inductor as component, on induction leakage inductance between the excitation winding and the plasma "secondary"), this is modulated to the HF current feeding the lamp, so modulate the lamp's output.
Square wave "high pressure" ballasts have their ballasting stage based on a DCDC regulator, what by it's action remove all low frequency ripple, then the current pass to low frequency chopper, what swap the polarity each few ms to avoid metal migration (but the swapping is immediate, within few us the polarity reverse, so it does no effect on the lamp output)
