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Aqua-Signal 1044 24v DC inverter output. Looking at the output of the 24v inverter found in this marine twin 20w fluorescent fitting. Runs the lamps at 35khz and seems to operate them at about 15w each. *** You get more luminous flux from running at higher frequency but I still don't think that would equal a normal lamp at 20w tbh. Also quite a messy output sinewave. You don't get that with mains voltage HF gear. The current also seems to be slightly out of phase. It is 25 years old though! ***edit: due to my shit cheap current probe the lamps may actually being driven at higher power lol...

Aqua-Signal 1044 24v DC inverter output.

Looking at the output of the 24v inverter found in this marine twin 20w fluorescent fitting.
Runs the lamps at 35khz and seems to operate them at about 15w each. ***
You get more luminous flux from running at higher frequency but I still don't think that would equal a normal lamp at 20w tbh.

Also quite a messy output sinewave. You don't get that with mains voltage HF gear. The current also seems to be slightly out of phase.
It is 25 years old though!

***edit: due to my shit cheap current probe the lamps may actually being driven at higher power lol...

387A9408.JPG 8456E849-9D70-4552-8D57-1D99125F01F5.jpeg AS20winverter.jpg coachlightpls.jpg DPP00002182.JPG
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Filename:AS20winverter.jpg
Album name:FrontSideBus / Tests & Experiements
Filesize:335 KiB
Date added:22 Oct, 2019
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URL:http://80.229.24.59:9232/gallery/displayimage.php?pid=12844
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Ash   [22 Oct, 2019 at 08:32 PM]
Most likely there isn't much inside other than a Royer oscillator. It have to have feedback gain >1 to oscillate. Most line power ballasts are somewhat more advanced than that. The waveform shows how there aren't really "zero crossing restrikes" at such frequency, the plasma doesnt have the time to go out..

The phase shift and smooth current waveform look to me like simply bandwidth limits of your current probe
FrontSideBus   [22 Oct, 2019 at 09:10 PM]
Actually yeah I forgot, my shitty cheapy current probe (Hantek CC-65) only has 20khz bandwidth... LOL so that makes this image completely pointless lol.
It's been so long since I used it but it did what I wanted it to do just fine originally lol.
Ash   [22 Oct, 2019 at 09:34 PM]
It is not too bad in this shot, i'd say it is attenuating significantly at 200K+. With a probe that really goes down after 20K we would be looking at clean sine here with 1/2 of the amplitude...
FrontSideBus   [22 Oct, 2019 at 09:54 PM]
If it's -3db down at 20k who knows how fast it drops off after that lol. I'll grab a picture of the inside of the ballast, it's got a very nice thick conformal coating on it.
Ash   [22 Oct, 2019 at 10:44 PM]
For simple single pole filters the transfer function is approx -3dB in the corner and 20 dB/dec in the slope. So for a 20K lowpass it will be 0db drom DC to 20K, and -20dB/dec starting from 20K on. The corner itself comes out rounded so that at 20K there is approx -3dB and not 0dB. I dont know whether the probe is single pole tho, maybe it have more than one pole (i.e. more than one place where lowpass filtering happens)

Some types of conformal coating glow quite well under BLB

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