LOLbooster Update: Power Supply Design Issues Pt. 3
After struggling all weekend with the problem of regulating the track voltage, I’ve decided to simply remove this feature from LOLbooster. The fact that the LMD18200 shuts down when its voltage input drops below 10V presents a problem too difficult for me to surmount. Perhaps later, I will design a more advanced booster that uses discrete switching elements that will permit relatively easy track voltage regulation, but for the sake of my own sanity, and to keep the project manageable, such will have to wait. I’ve got nearly the rest of the booster breadboarded, with only the...
read moreLOLbooster Update: Power Supply Design Issues Pt. 2
A little fiddling on the breadboard revealed some interesting results. The LMD18200 shuts itself off when the input voltage falls below 10V, as a safety precaution perhaps. When this happens, if the LM338 voltage regulator is monitoring the LMD18200 outputs, and the LMD18200 is shut off (because, e.g. of a fault condition, or because I shut it off manually), the voltage on the outputs becomes 0V, and the LM338 output falls to about 3–4V. And stays there. No matter what. Re-enabling the LMD18200 does nothing, nor does twiddling the adjustment trimpot. The whole system has to be reset. The...
read moreLOLbooster Update: Power Supply Design Issues
I got my bigger breadboards, and I began prototyping the bit of the design of which I am least confident: The voltage supply to the track. Recall that the design was meant to monitor the track voltage, and adjust the supply voltage to keep the track voltage steady, to compensate for voltage drops due to large loads on the tracks. The design I created reflected a fundamental misunderstanding of how adjustable voltage regulators work, and so failed. Unsurprising, really. But, what’s more, at some point I had two pins on the LM338 swapped, and, although it is hard to be sure, I may have...
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