hans_van de burgt Posted March 1, 2015 Share Posted March 1, 2015 I want to use an Arduino as a DCC decoder for points. It's possible to use e.g. 4 separate servo's.The Arduino is connected to the DCC bus from my eLink interface via an optocoupler.I want to know how I can power the separate servo's. Is it possible to convert the 15v from the DCC bus to 5v for the servo's. Or do I have to use a separate 5v power circuit?grzz, Hans Link to comment Share on other sites More sharing options...
Chrissaf Posted March 1, 2015 Share Posted March 1, 2015 Personally, I would try to reserve as much DCC current as possible for running locos. Using the DCC signal sparingly for other functions. If you are optocoupling the DCC signal into the Arduino micro-processor, then I don't see any reason why you shouldn't power the Arduino and servos from a dedicated supply that is fit for purpose. I use these for 5v up to 150mA current:http://www.rapidonline.com/pdf/156892_da_en_01.pdfor these for 5v up to 1Amp (there is a 6v version in the range if you prefer for servos).http://www.rapidonline.com/pdf/47-3290e.pdf If you do use the DCC supply, bridge rectify the DCC signal first before connecting to above. But personally (as I stated earlier) I would use a separate power supply, not the DCC signal to provide the servo voltage / current. Servos contain electric motors and electric motors are electrically noisy. I would recommend as much electrical separation as possible between the servo and the DCC signal. The 5v 150mA regulator combined with a bridge rectifier I have used via the DCC signal to provide 5v supply for coach lighting. The 5v 1Amp regulator version I have used for a 2 x 4 servo board (total 8 servos), but in this instance dropping down from a dedicated 12 volt DC supply not the DCC signal. The 12v supply runs my micro-processor control board, with the derived 5v rail from the regulator being used to drive the servos because as you are obviously aware, the servos operate on a typical max voltage of 6v. Out of curiosity, I find it strange that you are asking this question about simple power regulation circuits, when you seem to have a working knowledge of Arduino and interfacing it to DCC, and presumably writing your own software code to make the Arduino function as a DCC decoder. Link to comment Share on other sites More sharing options...
PJR_slo Posted March 2, 2015 Share Posted March 2, 2015 For use with servo motors, I would use a separate unregulated 9V power supply and then regulate to 5V with the 1 amp regulator. Using the regulator from 15V or 16V could generate too much heat within the regulator. As Chris says, the noise generated by the servo motors should be kept well clear of the DCC signals. One thing to note is that the ground rails must all be common. That is the 0V rail from both the Arduino and servo regulator have to be connected. The choice of regulator will depend an the number of servos to be powered and their maximum current draw. Peter Link to comment Share on other sites More sharing options...
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