Stay Alives

[adanapress]

Can anyone advise me on the possibility of a stay alive wired simply in curcuit  in typical 00 diesels, or indeed in steam models.  I would only be seeking maybe one wheel revolution, perhaps one and a half..  I am definitely analogue, DCC is not for me, tho' I do know its available in the DDC world..  I do understand about the need for clean track and wheel discipline, and do my best, but a smidgin of  'freewheel' would be good ...

[devondynosoar118]

You cannot easily use capacitors in that way on DC, since in one direction the output will be the wrong polarity. You can get around that but because the voltage into the loco varies on DC you will have to run at high speeds to charge the capacitor to a level where it will make any difference to a disruption of the track feed.

Perhaps radio control with a battery in the loco might be a better solution in this case?

Edited September 25, 2018 by devondynosoar118

[AndyID]

Can anyone advise me on the possibility of a stay alive wired simply in curcuit  in typical 00 diesels, or indeed in steam models.  I would only be seeking maybe one wheel revolution, perhaps one and a half..  I am definitely analogue, DCC is not for me, tho' I do know its available in the DDC world..  I do understand about the need for clean track and wheel discipline, and do my best, but a smidgin of  'freewheel' would be good ...

 

As Devonwotsit says, it's really only possible with DCC, and RC with battery is another way to go. With DC you should be able to achieve similar results with flywheels if there is room to fit them into your locomotives.

[Guy Rixon]

You would need a separate stay-alive circuit for each direction of travel, with diodes on the inputs and outputs to make sure that the capacitor in each circuit never saw a reverse voltage. DCC stay-alive units must present similar design-problems (the capacitors have to be in the DC-output stage), so I'm sure it can be done.

 

As noted above, the unit would only stay charged when the engine was running at speed, so it wouldn't help with starting away or low-speed running.

[AndyID]

I have recently fitted 100 volt 22 microfarad non polarised capacitors to a Bachmann 9F and Class 66 loco.

 

I have 10 volt 1000 microfarad capacitors but these blow to quickly even if used as 2 together.

 

The 100 volt capacitors certainly do help to keep the locos going when they meet a dead spot on the rails.

 

In theory you can create a non-polarized capacitor by connecting two polarized (electrolytic) capacitors in series "pointing" in opposite directions. Assuming both capacitors have the same capacity the effective capacitance of the series combination will be half the value of one of the capacitors. I've not tried this in a locomotive but it might be worth a shot.

 

EDIT: On reflection, I think that's a complete load of baloney! It should work with AC, but I'm pretty sure it's not going to work with DC.

Edited September 26, 2018 by AndyID