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As I understand it, TMCC and DCC are not compatible mainly because TMCC uses sine wave, while DCC is pulsed AC.

It seems it would be simple enough to build some circuitry that could be installed in an individual engine  to convert the sine wave into pulse before feeding it into the engine's DCC decoder, thus allowing both types of engines to run on the same track with the same power source, and merely needing separate hand-held controllers for TMCC and DCC.

I was thinking OP Amp, but am concerned with current draw.

Ideas on if this can be done, and if so, how?


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The DCC signal is an AC square wave at around 29K Hz but it isn’t a perfect square wave. The tops and bottoms of some of the squares are lengthened to make the zeros and ones which make up packets of instructions. This is why DCC works so well. It’s because the power is also the signal or instructions to the locomotive. You can’t have one without getting the other. With your idea how would the ones and zeros get to the locomotive? 

Last edited by Hudson J1e

I think you got a good idea but how about a circuit that filters the DCC signal and changes it to a sine wave. Then the TMCC locomotive would get the power it needs to operate while getting its instructions through the antenna?

But I guess that won’t work because I think TMCC needs the 60Hz signal to broadcast the instructions. 

One time I ran a PS2 locomotive in a DCC block and I could hear the DCC signal in the speaker of the locomotive. It seemed like it was going to work but I didn’t want to chance damaging the electronics. 

Last edited by Hudson J1e
Trainman2 posted:

The Dcc power source must convert the 60 Hz a.c. to the 29 kHz somehow before it goes out to the track. 

I was wondering if the same circuitry could be installed in the engine rather than the power source. 

That is certainly possible or doable but again how would you get the instructions to the DCC locomotive?

Matt Makens posted:

I ran a Legacy loco and an MTH loco off DCC power the MTH loco was in DCC mode and the legacy loco was running Legacy. Both ran and worked but the legacy loco had feed back thru the sound system.

Could you please post a sketch of the wiring, what DCC command hardware you used, and a video?  A couple months ago I asked about doing just this and was told it wouldn't work.

Sgaugian posted:

I realized DCC's underlying or base current is AC, but just so I have this right, analogy or sinusoidal 60Hz AC gets converted to squared off or flat 29kiloHertz - correct?   Thanks.  

Its difficult to equate DCC to a base frequency because "0" bits have a square wave period thats at least twice as long as "1" bits. 

Going off of memory, which is dangerous, but I believe 1 bits have a frequency of 8-9khz, and zero bits have a frequency that is half of that, but could be much lower due to a technique called zero-stretching. 

So while wall power is a continual 60 hz frequency, DCC varies the frequency of the alternating current so that the information can be passed and detected as 0 and 1 bits. 




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