Chrissaf Posted April 1, 2020 Share Posted April 1, 2020 Is my understanding of this correct?.No it is not..The 'Stay Alive' component does not go anywhere near the motor. It can't, because the voltage polarity on the motor is reversible and 'Stay Alive's' are polarity sensitive and will be damaged if connected to a reversed voltage..The block schematic below shows a typical DCC decoder. Note that the 'Stay Alive' is optional (why it is shown in dotted lines) and is located after the 'Bridge Rectifier' that converts the 'Bi-polar' DCC track voltage to DC, but before the decoder processor. The bridge rectifier ensures that the voltage across the 'stay alive' is a near constant and always the right polarity..The charge stored in the 'stay alive' is used to power the whole decoder circuit, not just the motor during the breaks in the track power. The location of the 'stay alive' is at a decoder circuit location that has a fixed constant DC voltage (typically 14.5 volts DC). The power to the motor is generated by the H bridge 'Motor Control' semi-conductor output. It is the H bridge circuit that generates the reversible polarity and DC pulses used to power the motor..The H bridge is in turn controlled by the software running in the DCC decoder processor. The processor can read the DCC digital commands on the track via the 'Command Signal Line' represented simply by the arrow path in the schematic below. It is this digital signal path that tells the DCC decoder processor what DCC command to perform../media/tinymce_upload/3ec7711763acc49598514cf24dca04ec.jpg.The graphic below gives a very simplistic overview of a simple H Bridge Motor Control circuit../media/tinymce_upload/8f4b795b27cb4f298da7f20ece7bb4ec.jpg.TIP: As a newbie poster, just be aware that the 'Blue Button with the White Arrow' is not a 'Reply to this post' button. If you want to reply to any of the posts, scroll down and write your reply in the reply text box at the bottom of the page and click the Green 'Reply' button..Particularly as my reply includes images. If you use the blue button, any reply you write, may be held back for image approval. Even though it is already a previously published image..See also – further TIPs on how to get the best user experience from this forum.https://www.hornby.com/uk-en/forum/tips-on-using-the-forum/. Link to comment Share on other sites More sharing options...
Chrissaf Posted April 1, 2020 Share Posted April 1, 2020 A question about this stay alive malarky, which I don't quite understand. The DCC signal gives a full voltage but "chopped" so that the speed of the train can be controlled. This has the advantage of giving full torque for the time in which the pulse is on because it is effectively 12V pulses. However if you put a capacitor in the circuit it will "average out" the voltage, only giving you full torque at 12V because you are actually getting a smoothed DC at a lower voltage rather than a pulsed DC at maximum voltage. Is my understanding of this correct? Link to comment Share on other sites More sharing options...
pinzgauer Posted April 1, 2020 Share Posted April 1, 2020 Brilliant, thanks for the circuit and also the posting tips. Much obliged to you Chris Link to comment Share on other sites More sharing options...
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now