Post all your model railway electronic problems, solutions and discoverys here.
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I have a panel mounted twin track controller, which needs two 16V ac supplies. I looked at the circuit board and the first thing the input power does is goes into a bridge rectifier. Instead of using 16V ac could I get away with say about 14.5V DC input instead? I've got several high output old laptop chargers that are around 18V and I thought that using them with a DC-DC buck would be fine. Thoughts?
Try it. Use The AC input, the rectifier will drop a couple of volts. If the input goes straight into a rectifier then you aren't going to run into the zero switching problem where you can't reach zero volts, (it would be fed raw AC if that was a possibility) If your locos prove to be a little too lively I'd stick another rectifier between PSU and controller to loose another couple of volts. I've run Gaugemaster units off a 21V AC supply nothing got upset by it. (actually the 14V and 6.3V windings of a filament transformer for pairs of florescent tubes, wired in series)
I can vary the voltage up to about 14.5 volts with the buck. They sell them so cheap on ebay its not worth making your own. The only thing I was worried about was over driving the controller, the output of the PS being smoothed dc, plus I also wondered if the controller used the AC ripple as a kind of pulse to help locos start better.
Gaugemaster have used various circuits over the years, I've never seen any attempt to categorise them. Suck it and see is probably your best bet. Running it from a laptop PSU I wouldn't bother with the buck converter. As I said I ran one off 21v AC for several years, with no detrimental effects. I'm currently running one of an 18v AC wall wart. I've modified the output wiring so that there's a voltmeter and micro ammeter in front of the reversing switch. It's very useful for checking mechanisms the ammeter twitches if there's a tight spot on the chassis, before you notice it in the movement.
Moving coil motors are better for watching the behaviour of small motors. The twitch in the current caused by a sticky coupling rod would go unnoticed on a digital meter. Analogue still has it's advantages.
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