Lenz LS150

Lenz LS 150 (buy)

General

The Lenz LS150 is a six-output decoder designed primarily to operate twin coil switch machines and relays. It provides an AC output pulse that can be programmed for durations from 0.1 to 10 seconds. A separate AC power source is required to provide the power to operate the controlled accessories. The AC power source cannot be provided by the track DCC voltage. The outputs are over-current protected and will turn off if the load draws excessive current. After an over-current trip, the AC power must be removed and restored to return to normal operation. Separate manual pushbuttons can be installed to operate the accessory directly rather than through the LS150. The LS150 will only operate one output at a time to prevent a large current draw from the AC source. If multiple switch commands are received, it will cue the commands and execute them sequentially in the order received. In this way, each output can draw the maximum amount of power without interference from other outputs.

The LS150 measures 4.75 X 2 3/8 X 13/16 and includes mounting feet for attaching to a flat surface. The LS150 can be set to six successive addresses or can be set to six random addresses. With the addition of two external diodes, the LS150 will work with a stall motor switch machine such as the Tortoise™ or other motorized switch controllers.

Installation of the LS150 is simple. The AC power source is connected to the AC terminals (marked ?), the DCC signal is connected to the J and K terminals, and then each controlled switch machine is connected to one of the outputs.

Feedback

There is no provision for feedback to the cab bus.

Programming

The LS150 is designed for programming on the main and does not require or use the programming track. Each output has two variables that can be programmed: the output address and the output pulse duration. The simplest programming mode sets the output 1 to a desired address and the other five outputs are simply the next five addresses in succession. To program the first address, the programming button is held until the LED on the LS150 shines continuously. Release the button, and use the accessory command on your cab to open or close a switch at the desired address for the first LS150 output. If the address change was correctly received, the LED will turn off. The LS150 is now programmed with the first output at your selected address and the next five outputs located at the next five successive addresses. In this mode, there is no provision to program the pulse duration. Unless otherwise set, the pulse duration will be the default 0.1 seconds.

The second programming mode allows the programming of the address and pulse width of each output independent of any other output configuration. In this mode, the programming button is pushed and held until the LED on the LS150 shines continuously. The programming button is then pushed again for a short period of time and the LS150 enters the output 1 program mode. The LED will flash one time with a longer blank period. A switch control command is sent to the desired address for output 1. When correctly received, output 1 is now set to this new address, and the LED starts to flash quickly, indicating that it is ready to program the output 1 pulse width. A switch control command is sent to the address value that is 10 times the desired pulse width (e.g. a 5 second pulse width is programmed by sending a switch control command to address 50). After successfully programming the pulse width, the LS150 will sequence to the second output to allow you to set up output two. The LED will flash two times with a long blank indicating that the LS150 is ready to program the parameters for output 2. The programming process is repeated until all outputs are programmed or until programming is terminated by pushing the programming button until the LED turns off.

If you become completely lost and incorrectly program the LS150, it does provide a lifesaver feature. A simple programming option is included that allows you to restore the factory default values for all programmable variables.

Manual

The sixteen-page manual is clearly written and provides detailed instructions on how to operate the LS150. It has clear instructions, including illustrations, of how to install the LS150, how to program it, how to use it. The manual uses a significant amount of space to define an acceptable AC power source. The manual recommends the Atlas Generator as an acceptable power source and cautions against the use of a source with a rating greater than 45 VA. It recommends the use of a 10-ohm series resistor with power sources rated at more than 45 VA. In the technical data, it is stated that the power source must not exceed 16 VAC.

I ran all of my testing with an Atlas Generator as the AC power source, but my unit measured 17.25 VAC when I connected it to the LS150, which is above the maximum recommended value of 16 VAC. Further, I determined that the source impedance of the Atlas Generator is 0.89 ohms, for a short circuit current of 19.3 amperes. This value is well below the recommended value of 10 ohms for use with other power sources. I determined that a power source with a higher VA rating (such as the Magnaforce unit) would perform identically to the Atlas Generator with a 0.56 ohm resistor in series with the output rather than the recommended 10 ohms. Further, the Magnaforce device has an unloaded output of 16.74 volts rather than the 17.25 put out by the Generator.

Since the LS150 is rated for up to 3 amperes output, the recommended 10-ohm resistor would cause a 30 volt drop, almost twice the total available voltage (in real life, you would not get a 30 volt drop, but rather a short circuit current of 1.73 amperes rather than the 19.3 amperes available with the Generator). I would recommend the use of a 0.62-ohm (to account for tolerances in the source and the resistor) resistor with a 5 to 6 amp rated power source and a 0.91-ohm resistor if the source is rated for more than 6 amperes. These resistors should be rated for 5 watts or more. An appropriate Digikey part number is 0.62W-5-ND for the 0.62-ohm device and 0.91W-5-ND for the 0.91-ohm device. Use of these resistors will make a higher rated power source appear to be similar to the Atlas Generator while not limiting the maximum current available to operate your accessory.

Performance

Since the LS150 is designed primarily as a turnout control decoder, I tested it with the Nick & Jack International twin coil switch machine, the Peco twin coil switch machine, and the Tortoise™ slow motion switch machine. The LS150 was able to operate the Peco unit very well. Action was quick and solid, with the default 0.1 second pulse more than sufficient to provide excellent operation. I was surprised, however, to find that the LS150 was not able to operate the NJI machine. In fact, the NJI unit caused the LS150 to trip its over-current shutdown and turn off the output connected to the NJI unit.

I investigated this problem and found that during operation, the Peco switch machine drew approximately 0.8 amperes. I measured its coil resistance to be between 10.88 and 11.00 ohms. This implies an LS150 output voltage of 8.75 volts. The NJI switch machine has a coil resistance of 1.87 to 1.92 ohms, a factor of over 5 greater than the Peco device. This implies that the NJI switch machine requires about 4.6 amperes to operate, a value in excess of the LS150 rating of 3 amperes. This explains why the LS150 is not compatible with the NJI unit.

I also tried the LS150 with a Tortoise™ slow motion stall motor switch machine. I followed the manual by using two external diodes to connect the Tortoise™. I set the pulse width to the maximum value of 10 seconds, although 3 to 4 seconds would probably be sufficient to operate the Tortoise™. I measured 12.2 to 13.1 volts across the Tortoise™ while it was running, and an average of 6.59 across the Tortoise™ when it was stalled. These values are sufficient to ensure proper operation of the Tortoise™. In fact, I observed solid, reliable Tortoise™ switch machine operation. The problem is that the maximum pulse width is 10 seconds; there is no provision for a continuous output pulse. As a result, there are some cases where the Tortoise™ machine may back off holding the switch points in position due to a lack of stall current to hold the Tortoise™ in position. This is particularly true if a switch requires an exceptionally stiff spring to operate the points.

Recommendations

The LS150 is a good choice for operating low to medium current twin coil switch machines or other motorized accessories (crossing gates, signal flags, etc.) that require a short to medium length AC or DC (with external diodes) pulse to operate. The LS150 is not a good choice if you use high current twin coil machines such as the Nick & Jack International switch machine. Units with a coil resistance of less than approximately 3 to 5 ohms may have difficulty operating with the LS150. It is not the best choice for operating Tortoise™ or other stall motor style switch machines since it requires external components to operate these units and does not provide a continuous output. If you have a mix of switch motors, the LS150 will certainly work with a couple of stall motor machines mixed with twin coil machines.