Analog Command Control

r_i_straw · Oct 29, 2023

Many years ago I bought a used steam locomotive with an analogue decoder in the tender. I was told that it was made by a company called Dynatrol.

Power Systems Inc., introduced Dynatrol in 1978, now sold as Classic Dynatrol. Dynatrol is an 18-channel system (originally only 15 channels were offered), using a track voltage of 13.5VDC, and a frequency shift reversing system. It used audio tones to transmit commands. Additional channels were planned to control sound effects. It was one of the more sophisticated command control systems on the market.

One feature was walk around throttle with a memory feature. The plug-in channel selection made it very versatile, as well the ability to reset the circuit breaker from the handheld throttle.

Dynatrol featured three different throttles

The Full Function cab offered adjustable momentum, a rotary mainline brake controller and push button brake plus the throttle and direction controls

The mid-level cabs offered two independent direction selectors (MU-2) or three (MU-3) which allowed the operator to create and control a multiple unit lash-up

The Direct Function cab was a simple throttle with forward/reverse control

Dynatrol uses a supersonic carrier, with modulation of the duty cycle to transmit information to a pre-programmed receiver in the locomotive. Each throttle has its own oscillator and modulator, controlled by the throttle and brake controls. The carrier frequency is determined by a precision resistor installed in a small plug, called a channel plug. Reversing the locomotive is accomplished by phase shifting the carrier slightly. Receivers were available in various sizes that could fit N scale and larger locomotives. Multiple power supplies ($55 in 1979) and blocks were needed to reach the 15-locomotive capacity of the system.

Channels were selected using key plugs. Momentum and braking effects were also available.

Dynatrol suffered from the same issues as other carrier control systems. As the channel frequency increased, reliability decreased, especially as the receiver moved further away from the transmitter. Reliable signal strength was difficult to maintain at all points on the layout. Wiring had be robust, with minimal connections to avoid attenuating the carrier signal. Feeders were also very important to maintain signal reliability. The receivers were also rather large, imposing limitations on what vehicles they could be installed in.

The system has been on the market since 1978. Dynatrol and Onboard were among the most popular command control systems in use. Those two were among the more costly systems on the market, with a Dynatrol start set with 2 Full Function cabs and the base control unit costing $285 2023: $1400), plus the required power supply and filter capacitor costing an additional $50. Full Function cabs cost $15 more. Receivers cost $50 to $70 each, depending on their current rating. A basic direct or non-momentum cab cost about $65, and a full function cab was $75.

PSI was also working on a sound unit for the system in 1982.
Click to expand...

James Fitch · Oct 29, 2023

I remember reading about Dynatrol back in the olden days.

urodoji · Nov 21, 2023

I remember reading about it in Tony Koester’s column and imagining how cool command control must be, and seeing ads for the Wangrow System One which was like 800 early 90s dollars.

Doug Gosha · Nov 21, 2023

There was an even earlier system, from the early sixties, by G.E. called Astrac.

Doug

Log in or Sign up

Analog Command Control

r_i_straw Mostly N Scale Staff Member

James Fitch TrainBoard Member

urodoji TrainBoard Member

Doug Gosha TrainBoard Member

Share This Page

About TrainBoard

Useful Links

Places To Go: