Converting Old Peco Electofrog For DCC

[regme]

Hi

 

I want to wire up an old peco electrofrog for DCC.

 

This turnout does not have the gaps in the rail as the new turnouts do.

 

Just so I understand, on the back, I would cut the two small wires (red circle) and wire them to a switch to control the polarity of the frog.  Join the inner and outer rails to the positive and negative of the bus wire (red lines).

 

No need to do anything on the front especially cutting the rail at the yellow circle.  Where the yellow circle is there is a gap on the new turnouts where you would remove the smaller jumpers.

 

I hope that all made sense.

 

Cheers

 

Cheers

[WIMorrison]

What you are doing is modifying the turnout for reliability of operation and that is not specific to DCC - it is also something that should be done for DC operation.

 

From the pictures that you show and your description you have it correct, as long as you remember to switch the frog externally using a switch connected to the turnout motor and you add insulated rail joiners where you have the blue circle.

 

There is however a major caveat, and this is assuming that the back to back measurements are correct and wheel flanges are fine enough not to cause a short between the frog and the wing rails as these wing rails will be at opposite polarity from the frog (note polarity not negative and positive). This is why the rails are cut in the yellow circle on modern turnouts - again, not because of DCC, just to improve reliability of running.

Edited November 12, 2023 by WIMorrison

[DCB]

These points are really old and not suitable for modification for DCC.  They  don't have insulating gaps and cutting them to provide gaps  weakens them severely.   With no gaps  they  either short at the point blade as standard or at the frog when modified if a wheel set is under gauge.   Its not a big issue with DC but the short will trip DCC power.   The  2000 era Hornby wheel sets are really bad for this as the wheels can move sideways  if derailed.  A lot of DCC layouts have dead point blades, I have bought a number of ex DCC points with no continuity through the blades, due to burnt contacts and pivots (Just needed cleaning)    i prefer these to the later ones
To improve performance, if used in filthy conditions like outside, i fit a switch to change polarity of the frog in addition to the the point blades,  I use 1amp micro switches  but that's DC and I guess 4 amp would be more realistic for DCC, 

Edited November 12, 2023 by DCB

[mcowgill]

58 minutes ago, WIMorrison said:

This is why the rails are cut in the yellow circle on modern turnouts - again, not because of DCC, just to improve reliability of running.

Agreed that this is improves reliability, it's the way I was taught by my late father to build track over 40 years ago, bond the blades to the running rails and isolate the crossing with a switched supply.   But the impact of not doing this is much greater on DCC than DC.

 

With DC a turnout with both blades and crossing as one electical unit getting a brief short from a rogue wheel with narrow back to back might not be enough to trip the supply, on DCC that short will stop everything on the entire layout immediately, including lighting, turnout motors and anything else on the same bus/power district.  This is also why it's a good reason to have accessories/turnouts on bus that you can switch independantly from from the track bus.

 

Martin

[Dagworth]

If you don't cut the rails at the yellow circle you have created a short circuit

 

Andi

[WIMorrison]

7 minutes ago, Dagworth said:

If you don't cut the rails at the yellow circle you have created a short circuit

 

Andi

No he hasn’t - look at the pictures carefully 😉

[Dagworth]

22 minutes ago, WIMorrison said:

No he hasn’t - look at the pictures carefully 😉

With the links from the stock to switch rails in place there is a permanent short via the frog

 

Andi

[WIMorrison]

2 hours ago, Dagworth said:

With the links from the stock to switch rails in place there is a permanent short via the frog

 
which is why the op said he was cutting them …

[Dagworth]

Just now, WIMorrison said:

 
which is why the op said he was cutting them …

He said he was ADDING them.

 

Andi

[WIMorrison]

 

1 minute ago, Dagworth said:

He said he was ADDING them.

 

you must be reading another thread …

 

5 hours ago, regme said:

I would cut the two small wires (red circle)

 

[Dagworth]

5 hours ago, regme said:

Join the inner and outer rails to the positive and negative of the bus wire (red lines).

Definitely the same thread

Edited November 12, 2023 by Dagworth

[WIMorrison]

2 hours ago, Dagworth said:

Definitely the same thread

 

And if you look at the turnout picture you will see that the link between the frog and the blade will not exist after he has cut the connecting wires inside the red circle - therefore no short circuit.

[WIMorrison]

6 hours ago, DCB said:

I use 1amp micro switches  but that's DC and I guess 4 amp would be more realistic for DCC, 

 

Unless it is a very large gauge e.g. Gauge 1 that you are using the frog is not carrying 4A (or anywhere near it) when a loco draws power from the frog. The frog will be carrying around 200-400mA for a 00 scale loco, therefore lower current capacity switches are perfectly acceptable.

[Dagworth]

18 minutes ago, WIMorrison said:

 

And if you look at the turnout picture you will see that the link between the frog and the blade will not exist after he has cut the connecting wires inside the red circle - therefore no short circuit.

But the check rail and the frog will be opposite polarity so a short on every single wheel?

 

The cuts have to be made in order to improve the reliability otherwise it's better to leave as is but put the frog switch in so you aren't reliant on the contact between the switch blade and the stock rail.

 

Andi

[WIMorrison]

7 hours ago, WIMorrison said:

There is however a major caveat, and this is assuming that the back to back measurements are correct and wheel flanges are fine enough not to cause a short between the frog and the wing rails as these wing rails will be at opposite polarity from the frog (note polarity not negative and positive). This is why the rails are cut in the yellow circle on modern turnouts - again, not because of DCC, just to improve reliability of running.

 

[Dagworth]

Guess @WIMorrison and I were singing from the same hymn sheet, just on different verses...

 

Andi

[regme]

Thanks for the comments

 

When looking at this turnout, it looks like the gap between the inner rail and frog is wide enough not to create a short circuit when the wheels cross over it.

 

However, as WIMorrison said there is a caveat that a wheel may touch both, hence cutting the inner rails at the yellow circle is more of any insurance to prevent a short circuit .

 

Also a DCB said cutting the rails may weaken them, other good point to consider.

 

I could test my locos and wagons with the biggest wheel diameter to see if a single wheel will bridge the gap to create a short, then that will dictate whether to cut the rails or not, or cut my losses and buy new turnouts.

 

Upon further searching I found this on the "wiringdordcc" web site I found this, where he also cuts the rails.

 

May be cutting the rails as close and as fine as possible (not using a dremel) is a solution.

 

 

Thanks

Edited November 12, 2023 by regme
extra information

[Dagworth]

7 minutes ago, regme said:

May be cutting the rails as close and as fine as possible (not using a dremel) is a solution.

Where I've used old points I've always cut with a razor saw after the points are laid, less chance of any damage I find.

 

Andi

[regme]

Thanks, I have a scroll saw so I thought I'd give that a go.

 

The Dremel is on the top, scroll saw on the bottom, compared to the new turnout.

 

The scroll saw seems pretty close, might be the weapon of choice.

 

Edited November 13, 2023 by regme
forgot image

[RFS]

1 hour ago, regme said:

Thanks, I have a scroll saw so I thought I'd give that a go.

 

The Dremel is on the top, scroll saw on the bottom, compared to the new turnout.

 

The scroll saw seems pretty close, might be the weapon of choice.

 

 

Where you have gapped flexi-track to provide electrical isolation, I would recommend filling the gap with epoxy or araldite. Otherwise as the temperature fluctuates you could find the gap closes and causes an unexpected short. Had that a couple of times after a hot day!  Points are less susceptible as the track is more firmly held in place.

 

[regme]

Good point (sorry)

[rogerzilla]

18 hours ago, regme said:

Good point (sorry)

I hoped this would turnout well.

[regme]

2 hours ago, rogerzilla said:

I hoped this would turnout well.

I'm here all week, try the veal

[Brian]

If you can't afford a Scroll saw or don't have room for one, then a Jewellers Piercing saw works just as well. 😄

Used of course off the layout  Example of a saw