The CTM Relay Board is an expansion board for the universal MIDI control electronics CTMC64.

The reason for this additional board is the limited cable length between CTM64 main board and the contacts (max. about 50 cm / 2 ft). By means of the relay board the cable length can be extended to 100m/300ft and even more.

The working principle is very simple: The relay board is equipped with 16 reed relays that can be switched via very long cables. The relay board is placed near the CTM64 main board and the contacts inside the relays are the new contacts for the CTM64 main board. Thus the cable length between the contacts and the CTM64 main board is less than 50cm but the cables used to switch the relay can be much longer. For each relay a screw terminal is available to connect a simple 2 pin cable with the controlling contact on the other side (e.g. a momentary or toggle switch). The relay board is operated with a separate power supply to obtain a complete galvanic separation between the relays and the CTM64 main board.

• 16 Reed relays, the contacts of the relays are used as the contacts for the CTM64 main board
• response time of the relays less than 2 milliseconds
• relay connections via 2 pin screw terminal for each relay
• cable length up to ~ 100m/300ft (we tried cables up to 100m but probably even longer cables are possible)
• up to four CTM relay boards can be connected to one CTM64 main board
• separate power supply for the relay board(s), independent from the power supply of the CTM64 main board. An external power supply with 7-12V DC output is required. The current depends upon the number of relays that have to be switched actually. Each relay consumes about 10mA. The full installation (i.e. 4 relay boards, all relays in operation) requires a power supply with about 640 mA.
• additional screw terminal to operate several relay boards with one power supply only (if no galvanic separation is necessary even the power supply of the CTM64 main board can be connected to this terminal, provided that the power supply is sufficient)
• connection between each CTM relay board and the CTM64 main board via 16 pin ribbon cable, and one single cable (common line) that leads from the CTM64 main board to all relay boards - the 16 pin ribbon cable is included with the relay board

The power supply has to be ordered in addition!