DCC Voltmeter Adapter

A device to provide a more correct representation of a DCC signal voltage than is given with an "RMS" AC Voltmeter. This interface circuit to allows a regular DC voltmeter to read the DCC track voltage accurately.

This circuit can be used to measure voltage drop across bridge rectifiers or other decoder components, DCC input signal to boosters, or simply DCC voltage on the rails.

The circuit can also be used to measure DCC current draw (Amperage) by connecting the inputs of this interface circuit across a 0.1 Ohm resistor. This resistor is placed in series between the power station and the DCC load. The meter voltage reading is multiplied by 10 to determine Amps. Ie: Meter reading Volts times 10 = Amps in circuit. (Currents of less than 1/4 Amp may be indicated with reasonable accuracy using a 1.0 Ohm resistor. In this case Meter reading Volts = Amps in circuit.)

Circuit

The schematic is provided for public use by North Coast Engineering . No specific warrenty is provided or implied.

Adobe Acrobat format (12KB)

Parts list

R1, R2 : 4.7K (1/8W or larger)
R3 : 470K (1/8W or larger)
C1 : 1000 pF (disk or mica, 24V or larger)
C2, C3 : 0.1uF (disk or MLC, 24V or larger)
Q1, Q2 : 2N4403
Small Breadboard (or other assembly medium)

Last updated 9:54 PM May 18, 2001 John Balogh