Doepfer CTM64 Relay Board - Manual (Page 3)

Connections
Power Supply BU1
The relay board requires a power supply that is connected to this socket. A plug-in type
external power supply (AC adapter) is used. The power supply is not included with the relay
board and has to be purchased separately. One reason for this feature is electrical safety.
Keeping danger voltages (main) out of the board increases the electrical safety. Therefore an
external power supply of high quality and safety should be used. If the device is used in
Germany the external power supply has to be VDE approved. Another reason for the
external power supply is the fact that line voltages and plug types vary considerably from
country to country. Using a plug-in external supply the board can be used any where with a
locally purchased power supply, thus keeping the retail price down.
The power supply must be able to deliver 7-12 V DC unstabilized or stabilized voltage, as
well as a minimum current of 160mA (if more than one relay board has to be powered by the
same power supply the required current depends upon the number of the relay boards). The
board is powered by plugging the AC adapter into a wall outlet and connecting it to the
socket BU1 on the relay board. There is no separate ON/OFF switch. If the polarity of the
power supply is incorrect, the relay board will not function. However, there is no danger of
damage to the circuitry since it is protected by a diode. The correct polarity is: outside ring =
GND, inside lead = +7...12V.
The LED D17 below the screw terminal X17 is used as power display. This LED has to turn
on as soon as the power supply is plugged into the socket BU1. Otherwise the power supply
has the wrong polarity, unsuitable electrical properties (voltage/current) or is defective.
Screw terminal X17
This screw terminal is internally connected to the power supply socket BU1 and is used to
pass on the power supply to other relay boards if applicable. In this case only one power
supply is necessary. The power supply is connected to socket BU1 of one relay board only.
The other relay boards are connected via the screw terminals X17 among one another. But
even a separate power supply for each relay board can be used. In this case the screw
terminals X17 remain unconnected. Each relay board requires about 160mA. Consequently
for the maximum extension (i.e. four relay boards) a power supply with at least 640mA is
required. To be on the safe side we recommend the usage of a power supply that has a little
bit more current available than required (e.g. 700 mA or 800 mA for the maximum extension).
One of the screw terminals X17 can be even used to supply the CTM64 main board (the
main board requires additional 100mA). In this case only one power supply is required for the
complete assembly but the CTM64 main board and the relay boards are no longer
galvanically separated from each other. This may cause problems especially with long
cables. We recommend to use a separate power supply for the CTM64 main board and the
relay boards.
JP2 (2 pin connector)
The terminals of this pin header are internally connected (a 2 pin connector is used only
because of the improved mechanical stability compared to a one pin connector). One of the
pins is connected to the common connector JP6 on the CTM64 main board with a simple
single-pole cable. If two or more relay boards are used JP2 of each board is connected to
JP6 on the CTM64 main board. It is also possible to connect JP6 of the CTM64 main board
to JP2 of the first relay board and to daisy chain the JP2's of all relay boards.