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Need Advice: Dual Decoder & Block Occupancy Sensors Questions

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  • Member since
    December 2004
  • From: Pa.
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Need Advice: Dual Decoder & Block Occupancy Sensors Questions
Posted by DigitalGriffin on Thursday, October 2, 2008 11:53 AM

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.

Don - Specializing in layout DC->DCC conversions

Modeling C&O transition era and steel industries There's Nothing Like Big Steam!

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  • From: Christiana, TN
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Posted by CSX Robert on Thursday, October 2, 2008 1:36 PM
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
  • Member since
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  • From: Sierra Vista, Arizona
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Posted by cacole on Saturday, October 4, 2008 7:10 AM

 CSX Robert wrote:

Here are some that specifically say "Works with DC or Command Control":http://www.wsaeng.com/Signaling_Solution/Products.html

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.

  • Member since
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  • From: Christiana, TN
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Posted by CSX Robert on Saturday, October 4, 2008 8:17 AM
 cacole wrote:


 CSX Robert wrote:


Here are some that specifically say "Works with DC or Command Control":http://www.wsaeng.com/Signaling_Solution/Products.html


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...


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

 cacole wrote:
...
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.


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.

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