Self build single capacitor voltage buffer.
Capacitors:
The capacity for the single capacitor voltage buffer should not be higher than 2200µF, to reduce the time factor to charge the capacitor.
In place of one large capacitor, could also use several smaller capacitors in parallel.
The capacitor has a fixed polarity. Don't swap the + and – connections. Danger of explosion!
On a garden railway (in the 22..24 voltage range) the voltage of the capacitor should be at least rated for 35V.
Charging Resistor:
Recommended minimum value is a 2 Watt 150 Ohm resistor, to limit the charging current.
The majority of central stations have problems with programming when the current is to high.
If several of these voltage buffers have been installed, some central stations will not start because of the high starting current.
Massoth central stations will tolerate higher starting and programming current, it is possible to decrease the value of the resistor to a 2 Watt 47 Ohm resistor.
Either a Discharging Diode 1N4007 1 Amp, or a Discharging Diode 1N5407 3 Amp:
It ensures for a fast and good current supply to the decoder, for when the track input is interrupted.
The voltage buffer should be connected only to the internal decoder voltage connections, ensure the RED + goes to DEK + and likewise the Black – goes to DEK -!
Voltage buffers can sometimes influence spurious effects when attempting to program decoders, provision should be made to isolate the voltage buffer, either if easy access, to disconnect the RED connection, or incorporate an On/Off Switch to disconnect the voltage buffer from the decoder.
Self build voltage buffers contain no additional electronics, any references to electronic control or CV’s in the decoder manuals are not applicable.
