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Solar SOX This is a pretty basic LPS driver I’ve had for years. Originally designed for running a 26w SOX direct from 12V DC as would be found in a solar PV installation off-grid. On a test, over a year or so, I felt the lamp didn’t last as long as I would have expected, so the ballast may under run the lamp slightly. The design includes a circuit protection fuse and a couple of diodes in reverse bias to prevent damage from wrong polarity connections. Oddly there are 3x 100R resistors in series for each of the transformer T1 feedback coils. I have simplified these to 300R in the diagram. It may have been there was a 24V version using the same p.c.b. layout. Keywords: Gear

Solar SOX

This is a pretty basic LPS driver I’ve had for years. Originally designed for running a 26w SOX direct from 12V DC as would be found in a solar PV installation off-grid. On a test, over a year or so, I felt the lamp didn’t last as long as I would have expected, so the ballast may under run the lamp slightly.
The design includes a circuit protection fuse and a couple of diodes in reverse bias to prevent damage from wrong polarity connections. Oddly there are 3x 100R resistors in series for each of the transformer T1 feedback coils. I have simplified these to 300R in the diagram. It may have been there was a 24V version using the same p.c.b. layout.
SOX12v.jpg DSC04216.JPG QL_85.jpg ISX18P_ignitor.jpg Screenshot_from_2017-12-07_22-09-38~0.png
Lamp/Fixture Information
Manufacturer:Solatek
Model Reference:ST116 SOX inverter
File information
Filename:SOX12v.jpg
Album name:Tuopeek / Gear
Keywords:Gear
Filesize:539 KiB
Date added:03 Jul 2026
Dimensions:1966 x 2500 pixels
Displayed:96 times
DateTime Original:2026:07:03 10:31:13
Exposure Time:1/250 sec
FNumber:f/5.6
File Source:Digital Still Camera
Flash:No Flash
Focal length:55 mm
ISO:450
Model:NIKON D3400
Software:Adobe Photoshop Elements 2.0
White Balance:0
URL:https://trad-lighting.net/gallery/displayimage.php?pid=1369
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Comment 1 to 3 of 3
Page: 1

Max   [Fri 03 Jul 2026 at 15:33]
Those three resistors in series may be there so as to meet a minimum power dissipation that cannot be met with a single 1/4W resistor. At what frequency does this circuit operate?
Tuopeek   [Fri 03 Jul 2026 at 21:59]
The frequency measures at 30kHz with a close to triangular waveform. Hadn't thought of sharing the load in series arrangement but could be.
Max   [Sun 05 Jul 2026 at 15:37]
30 kHz is not unusual for such circuit, but a triangular waveform is not optimal for SOX lamps. Not sure if that's the cause of the reduced lamp life though. The system's characteristics during run up can be as important, if not more, as during full regime. So, we're missing information to properly understand the problem at hand here.

Comment 1 to 3 of 3
Page: 1