Smoke Unit Instructions - ESU version 3.5

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AC Relay

The smoke unit must be setup for stand alone operation, NOT in conjunction with its companion battery and timer/charger circuit as used on DC layouts.

Your DCC decoder must have  two spare function outputs, one to drive the heater unit and the other to drive  the fan. In addition to the smoke  unit and DCC decoder you will also need a zero cross over AC relay. Available  from RS components, Stock No 244-9019

These relays operate  in a  similar way to traditional relays, except that they are specifically  designed to  switch AC power which they guarantee to do at the 0v cross over  point, something  that cannot be guaranteed with traditional DC mechanical  relays. Other  advantages are:- Physically very small, almost silent in  operation, no moving  parts.

It is suggested that  the  relay is mounted on a small piece of Vero board or similar and connections  made  to the board rather than the pins of the device directly.The output from the decoder  that is to power the heaters should be configured to pulse mode with as long a  duration as possible, preferably with a longer off time than on  time.

The heaters will take a little longer to reach operating temperature but due to the cyclic action  will  remain warm if left on. The heaters can be switched off at any time simply by  turning off the function output on the decoder as you would for lights or sounds  etc.

The output from the  decoder  that is to power the smoke unit fan should be “dimmed” to the maximum  amount possible. Failure to do so will result in the motor running very fast  which  may  damage both the motor and decoder.

Thanks to Simon Varnam for this information