Need Advice: Dual Decoder & Block Occupancy Sensors Questions

Model Railroader Electronics and DCC
1

Question #1

What DCC decoders have the lowest starting voltage on DC layouts? I would really like a decoder to start operating on a DC layout as low as 2, 3 Volts, and handle up to 12V DC.

Question #2:

Are there occupancy detectors (current based) that work on both DC and DCC?

These questions are being asked to be used on a dual mode layout as it is slowly switched over from DC → DCC.

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  1. Pretty much ANY dual mode DCC decoder will start with just a few volts. But when it comes to sound decoders, it requires more voltage.

  2. None are available.

David B

3

  1. Dual mode decoders will operate on a few volts, but not likely down to 2 or 3 volts, the level you specifically asked about. The processors they use in the decoders typical require around 2 volts to operate. The power has to go through a bridge rectifier and regulator before it gets to the processor. The rectifier will drop around 1.2 volts, and you will get at least a slight drop through the regulator.

  2. YES. Some current detectors that are designed to work on DCC will work on DC and vice-versa. Here are some that specifically say “Works with DC or Command Control”:http://www.wsaeng.com/Signaling_Solution/Products.html

4

Do you have any personal experience with this product? Their description is a little confusing to me because there is a difference between Command Control (the old Dynatrol system, ASTRAC, and others) and Digital Command Control (DCC). They don’t say DCC.

Most people who build layouts intended to operate only on DCC don’t wire for blocks, so their instructions imply that I would have to go back around and completely rewire my layout into blocks to use their detector.

5

No, I don’t have any personal experience with their products, but if you download the manuals, they specifically say that they work with Digital Command Control.

I have seen other current detector circuits that will work with both, but I do not remmeber where right off hand, and doing a quick search, these are the first ones I found. The basic principle behind current detection is the same for DC and DCC, so it is not hard to develop a circuit that is useable with both

To use any form of current detection, you absolutely will have to divide your layout into blocks, because current detection works off of the current being used within the detection block. If you do not want to divide the layout into blocks, you will have touse some other form of detection, such as photodiodes or red switches.