I have 3 separate blocks on my layout: Main 1, Main 2, and the yard. I have 3 PWM controllers for those blocks, and an issue I’ve noticed is that a train will surge forward briefly when crossing between blocks. This is caused, I believe, by the pulses overlapping and causing the motor to briefly go to near full throttle.
To solve this, my plan is to a wire jumpers between the 2 blocks. That way I can power one off via a master switch I’ll have on my control station, flip on the switch for the jumper, and control both blocks with one controller for a smooth transition. Once the train is out of the original block, I’d flip off the jumper and turn the other block back on.
Are there any potential issues with this idea, and how should I wire the switch to ensure the circuit between the blocks is completely dead?
Your idea does have potential, but in my opinion a better solution might be to install short “transition sections” between the blocks–perhaps the length of two locomotives. Then, install a DPDT switch for each transition section. The switch will control which of the two adjacent power supplies run the transition section. I can make a diagram if you are interested in this system.
It wouldn’t hurt. I do plan to upgrade to DCC within a year though, so whatever I do won’t even be needed anymore. I just need to do something to allow for decent operation before the DCC conversion. So I’ll probably do the simpler of the 2 options.
Okay–in that case, mine is a little more complex because it will involve insulating additional track. So I’d go with yours–I’ll rig up a diagram quickly.
Single Pole, Double Throw, Center off (but usually you can only find the more common double pole)
If the polarity doesn’t match between cab A and B, it is a short. If the polarity does match the engines(s) either speed up or slow down to the average voltage between ‘blocks’ until the gap is no longer ‘bridged’ by either engine.
I’ve used this system, even having as many as five ‘cabs’ using a rotary switch as a block selector.
After removing all this stuff in 2005 and moving into the DCC realm — I don’t miss it!
when the other throttle is set to the reverse direction, there’s a significant short while the loco straddles the gaps.
If fast enough, momentum carries it across the gaps.
Once across the gap, the wheels spin backwards, eventually getting traction, slowing and reversing direction.
if not fast enough there’s just a short and the loco stops, straddling the gaps
If the other throttle is not set to reverse. The loco just continues across the gaps and is then controlled by the other throttle.
With 2 throttles, there needs to be at least 3 blocks, 2 blocks are needed whenever a loco leaves a block. With 3 blocks, only 1 loco can cross between blocks at a time.
How about inserting a transition block, then power it from the adjacent blocks with low resistance power resistors? That would average the running voltage between the two PWM controllers, and would require no intervention as you operate.
since it seems you really just want to control each block with a separate throttle, why not just set both throttle to the same direction and speed when moving loco from one block to another.
is there ever more than one loco per block? are there more than 2 locos?
UP_844 mentioned that he thinks that the pulse power packs may be fighting by pulsing power at separate moments, thus creating an abnormally long pulse and causing locomotives to misbehave.
Do we know what the specific power packs are, and what kind of PWM they are using?
Unless they are using a high synthesized frequency, the ‘pulse power’ whether at 60 or 120 pps will be synchronized to powerline 60 Hz, so there will be no ‘separate moments’, only a possible difference in apparent pulse duration if the power packs are putting out different waveforms.
I have been “all in” with DCC since I got back into model trains back in 2002.