!
WRM-4
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a
ms elektronik
5.3. Connecting subordinate circuits via a relay
Loads with a current consumption of more than 250 mA;
circuits or modules requiring to be galvanically isolated (e.g. track sections);
outputs of subordinate circuits
must be connected via a relay to the WRM-4 as a rule.
In addition you should connect a free-wheeling diode (e.g. 1N400x) in parallel to the relay in
order to avoid damages to the outputs of the WRM-4. Pay attention to connect the anode of
the free-wheeling diode (+) to the output of the WRM-4.
When supplying the WRM-4 with a.c. voltage, the relay possibly does not switch properly
("rattles") in operation. In this case you should mount an electrolytic capacitor (> 100 µF /
25 V) in parallel to the relay.
Attention:
When connecting
the outputs of
the
WRM-4
directly to the
outputs
of
subordinate
circuits (without
relay), current
possibly flows
back from the
subordinate
circuit into the
WRM-4. This
causes damage
to the output,
possibly to the
complete
WRM-4.
20 | Connecting subordinate circuits