MRC transformer

Bill Barnwell

Bill Barnwell

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Found this older MRC transformer that was in the garage and was all rusty, now I'm trying to figure out what all the switches do. There is a HO/G switch in the back above the power cord entrance that booses out going track voltage from anout 14vdc to 18vdc, on the front the top red switch is the power on/off switch and just to the left of it is a very small LED that glows red when the switch is in the on position. The bottom switch is the directional switch and there are also small red LED's that light when in on direction or the other. Now I'm left with the 2 center black switches. The one just above the bottom directional switch controls power to a reversing loop, but can't figure out what the 1 directly below the top switch (on/off) power. It is a single poll on/off switch and doesn't seem to control anything... Readers and ideas?MRC transformer.JPG
 
My guesses:
The reversing loop switch changes over polarity?
Could the other switch cut power to the loop??
OR
Control an accessory output on the transformer??

But it is a guess..
 
Based on a similar vintage MRC still in use, it may be a “pulse” option. Best left in “off” position (to the left).
 
PhilP said:
My guesses:
The reversing loop switch changes over polarity?
Could the other switch cut power to the loop??
OR
Control an accessory output on the transformer??

But it is a guess..
Click to expand...
actually I have found with the help of a reader, it is a model 6000 and the switch in ? is a pulse switch , Bill
 
PhilP said:
My guesses:
The reversing loop switch changes over polarity?
Could the other switch cut power to the loop??
Control an accessory output on the transformer??

But it is a guess..
Click to expand...
thanks for the help it is a pulse switch on a model 6000
 
Bill Barnwell said:
Found this older MRC transformer that was in the garage and was all rusty, now I'm trying to figure out what all the switches do. There is a HO/G switch in the back above the power cord entrance that booses out going track voltage from anout 14vdc to 18vdc, on the front the top red switch is the power on/off switch and just to the left of it is a very small LED that glows red when the switch is in the on position. The bottom switch is the directional switch and there are also small red LED's that light when in on direction or the other. Now I'm left with the 2 center black switches. The one just above the bottom directional switch controls power to a reversing loop, but can't figure out what the 1 directly below the top switch (on/off) power. It is a single poll on/off switch and doesn't seem to control anything... Readers and ideas?View attachment 241375
Click to expand...
mystery solved it is model 6000 and the switch in ? is a pulse switch, Thanks for every ones help, Bill
 
OK..
So, other than ?giving? a pulse.. What is it actually for? - I assume it is not an early defibrillator? :eek::oops::giggle::giggle:
 
Phil I guess the best way to explain pulse is a piece from model railroader
Borrowed this paragraph from NMRA website - NMRA Wiring


Quote:
The next step is to take a pack and add a switch for "Pulse." In a pulse throttle, half the AC wave cycle is used to produce a rapidly pulsating DC; a switch controls whether this is on or if the regular rectified current is used in the output. A good example of this throttle type is the MRC Throttlepack 501, which is a strong pack delivering 1.9 amps and has the pulse option. The reason for the pulse feature is better low- speed control, and it does work. In a sense, the pulses "push" the motor armature to help overcome inertia and friction. However, there is a fly in the ointment. The half-wave pulses cause extra heat to build up in the motor. Too much of this heat can cause the motor to burn out; some types of motors are more susceptible to this than others. While this isn't that common a problem, you should be aware of it. Pulse power should not be used for high speeds (it isn't needed there), and any loco that runs too hot may have other problems as well, (lubrication, tight gears).
 
Got it..
Half-wave rectified DC. - Presumably with no (or little) smoothing..
Thanks for the info..
PhilP.
 
Bill Barnwell said:
Phil I guess the best way to explain pulse is a piece from model railroader
Borrowed this paragraph from NMRA website - NMRA Wiring


Quote:
The next step is to take a pack and add a switch for "Pulse." In a pulse throttle, half the AC wave cycle is used to produce a rapidly pulsating DC; a switch controls whether this is on or if the regular rectified current is used in the output. A good example of this throttle type is the MRC Throttlepack 501, which is a strong pack delivering 1.9 amps and has the pulse option. The reason for the pulse feature is better low- speed control, and it does work. In a sense, the pulses "push" the motor armature to help overcome inertia and friction. However, there is a fly in the ointment. The half-wave pulses cause extra heat to build up in the motor. Too much of this heat can cause the motor to burn out; some types of motors are more susceptible to this than others. While this isn't that common a problem, you should be aware of it. Pulse power should not be used for high speeds (it isn't needed there), and any loco that runs too hot may have other problems as well, (lubrication, tight gears).
Click to expand...
Not sure that DCC Chips like the effect if fed this rather than true analogue DC?
 
Should be low enough frequency, that any decently designed decoder should cope??

There will always be an exception to this rule though. :nerd::rolleyes::nod:

And it will be the most expensive decoder, at the most inconvenient time, as well! :banghead::banghead:
 
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