| Archive for thecentralstation.myfreeforum.org Railway modelling for all Scales and Gauges |
| poliss |
DCC Voltmeter AdapterDCC Voltmeter AdapterA 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.) 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) http://jdb.psu.edu/nmra/dcc-v-meter.pdf |
| Teleman |
That looks very handy Pol |
| poliss |
If only I understood what it all means Pete. 
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| Teleman |
Well it means ....... whats the longest reply i can post as it takes a lot to explain  but in short its to old thing of 'normal' meters can't measure DCC voltage as its a signal not a voltage . This circuit changies it to a voltage that your meter can read , simple realy 
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| poliss |
I understand the (very) basic principles Pete, but when it comes to symbols on circuit diagrams Im lost.
I blame it on a miss-spent youth. While my mate was staying at home building all sorts of electrical gadgetry from the latest Heathkit electroncs catalogue, I was down the pub playing pinball and downing a few pints of Harp.
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