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There is also a version without SMD. This version is called 2. 1, slightly larger (80 * 100 mm) and equipped with dual drivers (to 1A load), but runs with the same software. The input voltage of the external power supply is fed to X2 (15V), type of current(AC/DC) or polarity does not matter, therefore a model train transformer, a power adapter or
decoder - schematic

the DCC signal can be used. The signal DCC can be also passed along on the board itself without external bridge by closing solder jumpers SJ6 and SJ7. The input voltage is rectified and by means of the usual 7805 series regulator the 5V for the processor are generated. The idle current is about 20mA, both the T0220 and the smaller T039 can be fitted. Note 1: I`ve noticed that some of Roco turnouts only switch at 15V, in this case due to the voltage drops across the rectifier and output driver the supply voltage need to be increased to 16V AC or 18V DC. Note 2: If only servos or DMX will be controlled, then a lower supply voltage of 7-9V makes life much easier for the 7805. I use here plug power supplies, which are `cheap` at the next recycling centre. The DCC signal is connected to X1. It is separated from the voltage supply of the decoder via an optocoupler (6N136). The optocoupler ensures a trouble-free operation even in large systems. 6N136 as well as 6N137 or 4N25 can be used. With 6N137, in addition, the Pin 7 (enable input) must be connected to pin 8 (this is not in the layout, because this pin must remain free when 6N136 is used). The 4N25 (or its derivatives) must be mounted as follows: pin 1 of the 4N25 connects to pin 2 of the layout (thus pin 1 of the layout remains unconnected). The 4N25 is relatively slow; in particular the release time is relatively long. The pull-up (R5) at the output must be scaled down to...



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