Hey. I started this build as an alternative at a power voltage divider able to offer reasonable voltage to supply the screen grids into a 6x6550 project. The available input voltage is 480-490V around and my intention was to reduce it to 360V somehow, keepin' the screen dissipation within the limit. At this voltage the screens draw at max power of 160W a total curent of 75 mA so the regulator should be able to support this current and bit more. ( roughly 30W).
I started inspired by this tubecad article :
![Click image for larger version Name: Screenshot_20240702_000053_Adobe Acrobat.jpg Views: 0 Size: 167.2 KB ID: 1001296](filedata/fetch?id=1001296&d=1720048098&type=thumb)
Using 1K series resistor and 12 pcs of 30V / 5W zeners I was able to make it stable for 100 mA draw within 15V regulation, meant less than 5 percent, which I consider pretty acceptable for application.
Assuring thermal conditions was a challenge. I ended with an unusual build, who helped by fan cooler ventilation keep the diodes at almost environmental temp. Measuring 30*C around on the diodes leads in a pretty proximity of diode case. It works very well for 2 days powered on my bench but I.m not sure I use it. It dissipate 40w. The unit is bulky and need to be fully ventilated, supposed will be mounted outside on the back of chassis. It have 70x70x210 mm.
![Click image for larger version Name: 20240630_125748.jpg Views: 0 Size: 959.1 KB ID: 1001297](filedata/fetch?id=1001297&d=1720048726&type=thumb)
![Click image for larger version Name: 20240701_175155.jpg Views: 0 Size: 805.4 KB ID: 1001298](filedata/fetch?id=1001298&d=1720048750&type=thumb)
![Click image for larger version Name: 20240703_010319.jpg Views: 0 Size: 712.8 KB ID: 1001299](filedata/fetch?id=1001299&d=1720048771&type=thumb)
A compulsory safety cage was considered...kind of...
I started inspired by this tubecad article :
Using 1K series resistor and 12 pcs of 30V / 5W zeners I was able to make it stable for 100 mA draw within 15V regulation, meant less than 5 percent, which I consider pretty acceptable for application.
Assuring thermal conditions was a challenge. I ended with an unusual build, who helped by fan cooler ventilation keep the diodes at almost environmental temp. Measuring 30*C around on the diodes leads in a pretty proximity of diode case. It works very well for 2 days powered on my bench but I.m not sure I use it. It dissipate 40w. The unit is bulky and need to be fully ventilated, supposed will be mounted outside on the back of chassis. It have 70x70x210 mm.
A compulsory safety cage was considered...kind of...
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