I didn't know; DCC locos run on analog

[mecgp7]

I posted on another thread about running DCC locos as analog units. I was told that DCC locos run best on DCC and even though they can run on analog, they don't perform as well. So I put it to the test and with the one DCC loco I have it is true. She runs ok on analog, but so much better on DCC. I never new.

[C855B]

Unless DC operation is locked out, or "brake on DC" is activated. In most decoders there are CVs to control both. In some situations it's wise to prohibit DC operation, as certain rare but possible combinations of conditions you can get runaways. I have a couple where I should take the time to check the CVs, as they go nuts if there's a momentary short.

[Rivet Miscounter]

Way back when, I used to buy the Atlas locos (like the GP38's and their 4-axle GE's) that came with the Lenz decoders.  I was amazed at how well they ran on DC.

Only caveat was on the hard core DC Pulse systems...then they struggled mightily and ran hot.  The club I belonged to at the time ran Aristo-Craft wireless throttles that had some sort of over-the-top pulse circuitry that did NOT work well at all with the Lenz decoders.   The only DC pack I had was the Troller "Auto-Pulse" and it wasn't much better.  But any MRC I ran them on was just fine, very smooth, low starting voltage.  You couldn't tell the difference if you didn't know.  The starting voltage was a tick higher but that was about it....they could still run pretty darn slow.

[peteski]

I posted on another thread about running DCC locos as analog units. I was told that DCC locos run best on DCC and even though they can run on analog, they don't perform as well. So I put it to the test and with the one DCC loco I have it is true. She runs ok on analog, but so much better on DCC. I never new.

If you think about it, the DCC decoder is a micro-computer which needs power to run its internal operating system, and to control power to the motor and to the functions (like headlights).  It is most at home when the decoder receives full 12V DCC power from the track.

While it can also run on DC, it first needs enough DC voltage to run the internal computer circuit.  This is usually 3-5V for non-sound and around 7-9V for sound decoders.  Only then it can decide that the voltage on the track is DC, and the appropriately send the power to the motor.  Since the power for the motor has to first pass the bridge rectifier all decoders have, then the H-bridge circuit that supplies power to the motor, it is not the same as running a non-decoder loco on DC.  Then as others mentioned, many DC throttles do not supply pure DC but either pulsing DC (rectified but not filtered) or even PWM (pulse Width Modulated) pulsing DC. those pulses can sometimes "confuse" some decoders into thinking that they are receiving DCC signal, causing them to to become erratic, or misbehave other ways.

It is always the best for DCC locos destined for DC operation to have the decoder removed.