The following is a method of finding high resistances in track power circuits. The digital voltmeter is set to its lowest range and indicates the resistance in the track circuit by measuring the voltage drop in a given section of track.
The movable jumper is connected across individual blocks in turn in order to check each one. A high voltage indicates a bad connection. The jumper must have as low a resistance as possible to avoid false indications
Two versions of the circuit are shown. Both work identically except that the second limits the current to one ampere.
The tester can be connected as far back in the circuit as desired so that toggle switches are also included in the test.
The diagrams show gaps in both rails although this would not normally be the case. The test will still work and might find bad rail joiners as well.
The explanations for the circuits on these pages cannot hope to cover every situation on every layout. For this reason be prepared to do some experimenting to get the results you want. This is especially true of circuits such as the "Across Track Infrared Detection" circuits and any other circuit that relies on other than direct electronic inputs, such as switches.
If you use any of these circuit ideas, ask your parts supplier for a copy of the manufacturers data sheets for any components that you have not used before. These sheets contain a wealth of data and circuit design information that no electronic or print article could approach and will save time and perhaps damage to the components themselves. These data sheets can often be found on the web site of the device manufacturers.
Although the circuits are functional the pages are not meant to be full descriptions of each circuit but rather as guides for adapting them for use by others. If you have any questions or comments please send them to the email address on the Circuit Index page.