This question comes up a lot. Here is a method using 2 relays where only 1 train runs on a loop in one direction. It can be made bi directional with more relays. That method is linked in my last post.
All 4 taps of PWZW are used along with 2 outside insulated rails to power the relay coils. Note the contacts are configured so that none of the transformer taps are connected together. There is no roller jumping,in fact center rail blocks are not needed if only 1 train is run on the loop only 2 outside insulated rails are needed. Careful placement must be made for these insulated sections as the coil will stay energized as long as any train car with metal wheels sits on the insulated section.Block detection using relays is explained here LINK
All the voltages can be set by the throttles. Click on any diagram to enlarge
If you do not have a multi tap transformer or do not want to use your ZW that way,you can make a voltage divider out of 25 amp bridge rectifiers as shown. Each half of the bridge drops voltage by about .6 to .7 volts so 5 bridge rectifiers will allow a 7 volt voltage drop span adjustable in .6 volt increments. Dropping voltage with diodes is explained more fully here LINK2
The first circuit would cost maybe $20 to make,depending on how cheap you can get the parts. The bridges cost maybe $3 each additional. Hook taps to a barrier strip for easy adjustment. Here is a pic of a voltage dropper made to vary the speed of super street cars in their respective blocks. Timers and relays switch and vary different voltages.
Dale H
