Guest Posted October 2, 2018 Share Posted October 2, 2018 Can anyone tell me which DC controller's use smoothed DC ? I know the Morley ones do and I know that gaugemaster do not ( well the 4 I have don't anyway) Link to post Share on other sites More sharing options...
Theakerr Posted October 2, 2018 Share Posted October 2, 2018 If it helps I seem to remember a U-Tube video where several smoothed and non smoothed were tested. Link to post Share on other sites More sharing options...
Guest Posted October 2, 2018 Share Posted October 2, 2018 I have seen the one comparing Morley and gaugemaster,quite interesting. Link to post Share on other sites More sharing options...
Bino Posted October 11, 2018 Share Posted October 11, 2018 What is a smoothed DC controller? Link to post Share on other sites More sharing options...
royaloak Posted October 11, 2018 Share Posted October 11, 2018 What is a smoothed DC controller? One with all the rough edges sanded down. Or have I misunderstood the question? Link to post Share on other sites More sharing options...
John ks Posted October 11, 2018 Share Posted October 11, 2018 The graphs show voltage over time The black line is the 0V reference With AC the voltage increases from zero to max & back to zero (positive polarity) & then to max & back to zero (negative polarity) This is one cycle, in Oz, UK & other power grids this happens at 50 times a second or 50Hz (60Hz in US) A single diode blocks every ½ cycle & you get ½ wave DC A rectifier flips every ½ cycle & you get full wave DC If you add a capacitor you get smoothed DC If you need to reduce the ripple on smoothed DC you need a regulator A good regulator will give DC that is ripple free like the DC you get from a battery Hope this helps John PS the astute among you will notice that the AC wave is not a sinusoidal, but for the purposes of explanation I think it is close enough. 1 Link to post Share on other sites More sharing options...
Junctionmad Posted October 13, 2018 Share Posted October 13, 2018 Just a small point , a regulator does not generally play any part in ripple control , the output capacitor is the primary determinant of ripple Dave Link to post Share on other sites More sharing options...
Crosland Posted October 14, 2018 Share Posted October 14, 2018 Another small point, a regulator Just a small point , a regulator does not generally play any part in ripple control , the output capacitor is the primary determinant of rippleDave The regulator is actually quite important. The circuit should be designed in such way that the regulator output voltage is lower than the minimum of the "smoothed" voltage from the rectifier + reservoir caps, also allowing for the regulator "drop out" voltage. Otherwise the regulator is not actually regulating at all, and the output could still have considerable ripple. Link to post Share on other sites More sharing options...
Junctionmad Posted October 14, 2018 Share Posted October 14, 2018 Another small point, a regulator The regulator is actually quite important. The circuit should be designed in such way that the regulator output voltage is lower than the minimum of the "smoothed" voltage from the rectifier + reservoir caps, also allowing for the regulator "drop out" voltage. Otherwise the regulator is not actually regulating at all, and the output could still have considerable ripple. indeed, however what I was trying to say is that the reservoir cap determines the ripple voltage , before the regulation stage and the regulator can ( if designed properly ) remove that , i.e. the regulator is not a determinant of the ripple voltage per se ( even if it removes it ) Link to post Share on other sites More sharing options...
AndyID Posted October 15, 2018 Share Posted October 15, 2018 the regulator can ( if designed properly ) remove that It's not much of a regulator if it doesn't Link to post Share on other sites More sharing options...
Junctionmad Posted October 16, 2018 Share Posted October 16, 2018 (edited) It's not much of a regulator if it doesn't well the LM317 "only" reduces it by around 50 dB !! Edited October 16, 2018 by Junctionmad Link to post Share on other sites More sharing options...
AndyID Posted October 16, 2018 Share Posted October 16, 2018 well the LM317 "only" reduces it by around 50 dB !! dBV? Link to post Share on other sites More sharing options...
Junctionmad Posted October 17, 2018 Share Posted October 17, 2018 dBV? no dBs , ie a ratio , works out round 700:1 reduction in 120 Hz ripple Link to post Share on other sites More sharing options...
Guest Posted October 17, 2018 Share Posted October 17, 2018 I am pretty certain the gaugemaster controller's output is 100hz. Link to post Share on other sites More sharing options...
Junctionmad Posted October 17, 2018 Share Posted October 17, 2018 no dBs , ie a ratio , works out round 700:1 reduction in 120 Hz ripple I merely quote the lm317 data sheet Link to post Share on other sites More sharing options...
AndyID Posted October 18, 2018 Share Posted October 18, 2018 no dBs , ie a ratio , works out round 700:1 reduction in 120 Hz ripple The decibel (dB) is a measure of relative power. If the LM317 data-sheet writers are using it to describe relative voltage they should probably use dBV instead. Alternatively they could use "ripple attenuation factor" or something similar. Link to post Share on other sites More sharing options...
Junctionmad Posted October 18, 2018 Share Posted October 18, 2018 (edited) The decibel (dB) is a measure of relative power. If the LM317 data-sheet writers are using it to describe relative voltage they should probably use dBV instead. Alternatively they could use "ripple attenuation factor" or something similar. while we are way of topic here , dB was originally defined in the context of power in telephony applications, but the modern SI definition of dB is a ratio of a "level" dBV is a ratio from a level of 1 volt ( as dBm is to 1 milliwatt) etc , Hence this would be an inappropriate suffix for the LM317 ripple rejection ratio dB is a simple ratio, when applied to power its 10 x Log 10 ( ratio ) whereas to Amplitude (as in this case ) , its 20 Log10 ( ratio) dB is therefore correct in this context , with a dB of 0 being 1:1 and 57 around 700:1 ( for amplitude ) Edited October 18, 2018 by Junctionmad Link to post Share on other sites More sharing options...
Guest Posted October 18, 2018 Share Posted October 18, 2018 So can anyone say what rating/type of capacitor would be best to smooth out DC from a gaugemaster controller. Would 1 or more in series or parallel be better? I am currently using a 3300 16volt bipolar one and it definitely smoothes out the feed to the track,the reason for this is my layout is both DC and DCC (not at same time obviously) most of my locos are DC but the ones that are chipped with DCC concepts decoders will not run at all on DC (yes DC is turned on in cv29) plus my club layouts are all DC only and I can't run my chipped stock on them so other than buying a Morley control I'd prefer to use a capacitor for now at least. Link to post Share on other sites More sharing options...
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