The tester is built and tested for immediate use.
It can be used on all gauges by touching the springy terminals onto the track and listening to noise on the track via the piezo    -  see the voltage of the track via the LEDs.
It will indicate the polarity of the track as well as the voltage, with 4 LEDs.
The piezo will buzz when DCC is present and the LEDs will indicate the positive rail and the presence of a voltage from 3v to more than 16v.
The MINI TRACK TESTER costs $5.50 USD plus $4.50 USD postage.
For more details see TalkingElectronics  dot com website and click on Track Tester where you will find a larger Track Tester with 4 LEDs that display the track voltage from 10v to 16v using a microcontroller chip.
Contact the design engineer: Colin Mitchell talking at tpg.com.au for any further details.
The $5.50 USD MINI TRACK TESTER will be posted to any country in the world for $4.50 USD.