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 LED Driver Prototype 1 So, what is this monster power supply going to power? LEDs, and lots of them. Some of these LEDs will always be on; some will be on under certain circumstances (e.g., on a day/night cycle); many will have special effects (e.g., traffic lights). To accomplish all of this, I have been working [...] Breadboard circuit After success building circuit described here on breadboard, I began construction of something more permanent this past weekend. But, as I did so, two events conspired to frustrate my efforts. First was the discovery, thanks to a member of the JNSForum, of the Lenz LF101XF function decoder, which does precisely what I designed my [...]  OSHI25-901 circuit board This is the lightboard from the OSHI 25-901 dining car from the Tomix 92950 “Yumekukan” set. This board sits in a fitted pocket in the galley of the dining car. There are three SMD LEDs (the three white boxes on the left); three long lightpipes run from the LEDs to the rear of the car. The middle LED lights the taillights and signboard, and only lights when this car is at the end of the train—it doesn’t light when the car is at the head of the train. The outer two LEDs light two rows of table-lamps in the dining room of the car, and remain lit whichever direction the train is running. The two leads on the right connect directly to two steel strips that run along the bottom of the car and (in addition to providing much-needed ballast) contact pickups in the trucks. So, when +12V is fed across the leads (I don’t know which direction, to be honest), all three LEDs light; when -12V is provided, only the outer two LEDs light. In addition to the LEDs and resistors, there is what I’m guessing is an SMD bridge rectifier (for the table-lamps)? Although it has six pins instead of the usual four. And there’s some other tiny little resistor like thing by the middle LED. The challenge before me: Convert this puppy to DCC. The board is too small to modify. And there’s no space to construct a replacement board. And, as many of my readers will know, controlling two independent lights with a DCC decoder requires three wires: Two “function” leads (that when activated, short to ground; when inactive they are left floating), and the +12V blue common. In my favor, there is a fair amount of room in the galley for additional circuitry, beyond just a decoder. This is the third in a series of articles (title above notwithstanding) about getting a Kato KIHA 110 working with DCC. In this first part, I hooked a decoder up to the motor, and got basic functionality going. In the installment, I outlined how wiring headlights for DCC works in principle. In this article, I demonstrate [...] Read the prelude to this article. Update (31 Dec 2009, 10:41AM) Corrected the schematic illustration showing how to connect a decoder to LEDs. The LEDs were connected backwards, oops! Update (21 Feb 2008, 10:07PM) In an earlier draft, I noted that the two endcars were treated completely differently. This, as I quickly realized, is not true. The instructions [...] |
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