Peco points power

[Saffie John]

I've been frustrated for days, struggling to get a rebuild/revamp of a dogbone layout working, but for the life of me, could not get points working. Then I discovered an illuminating chat from 4 years ago, with the same problem, and it was eventually solved by changing PSU to 16v. BINGO! Thanks, RM, for keeping old info up for us novices

[RexAshton]

Adding a capacitor discharge unit if you don't already have one will also work wonders.

[Phaeton]

Can I follow up in the CDU, I have 4x Peco points, just bought 4x Gaugemaster Seep motors for them, it's in a shunting situation so likely to be quite a bit of use. What size of CDU will be required?

[kevinlms]

2 hours ago, Phaeton said:

Can I follow up in the CDU, I have 4x Peco points, just bought 4x Gaugemaster Seep motors for them, it's in a shunting situation so likely to be quite a bit of use. What size of CDU will be required?

Any commercial CDU should work fine.

As others have suggested, the performance of any CDU can if required, be improved by slightly increasing the AC voltage input.

Note there is a limit to how far you can increase it by. The voltage rating of the capacitor(s) is the limitation. Typically 25 Volts DC. Any more than that and they will eventually explode, sending electrolyte everywhere!

The AC voltage is converted to DC, to the AC peak, which is usually 1.4 times the input.

[DCB]

Yes watch the voltage rating of the Capacitors. Most off the shelf CDU ones are a bit limp and they will charge to the peak voltage applied.  I blew up a 24 volt cap on a 16 volt nominal supply simply by leaving it charging for too long. If you stick with a CDU from the same folk that make your power unit you should be fine.  Mix and match it could go bang.    Not sure how dangerous the electrolite is but  mine stained the floorboards in the shed when the cap went "Pop"

[DavidB-AU]

Electrolytic capacitors should be rated at least 50% greater voltage than the expected peak. In other words for a 16V AC (meaning 22.4V DC) input you'd want capacitors rated for 35V or higher. 50V would be better.

 

Cheers

David

[Phaeton]

This is the one I was looking at only because they also do a bank of 4 switches as cheap as I can buy 4 switches & can save postage https://www.ebay.co.uk/itm/RKcdu1-2x-4700uF-Dual-Capacitor-Discharge-Unit-CDU-Hornby-Seep-PECO-Points-Motor/182307855737?hash=item2a72651d79:g:3rcAAOSwNIFd52Ms

 

https://www.ebay.co.uk/itm/RKtoggle7-Switch-Module-for-use-with-Solenoid-Points-Capacitor-Discharge-Units/183735482293?var=691324452987

 

 

[DavidB-AU]

12 minutes ago, Phaeton said:

This is the one I was looking at only because they also do a bank of 4 switches as cheap as I can buy 4 switches & can save postage https://www.ebay.co.uk/itm/RKcdu1-2x-4700uF-Dual-Capacitor-Discharge-Unit-CDU-Hornby-Seep-PECO-Points-Motor/182307855737?hash=item2a72651d79:g:3rcAAOSwNIFd52Ms

 

 

The capacitors appear to be marked 35V so that should be sufficient for 16V AC.

 

Quote

https://www.ebay.co.uk/itm/RKtoggle7-Switch-Module-for-use-with-Solenoid-Points-Capacitor-Discharge-Units/183735482293?var=691324452987

 

That seems overpriced for what it does. 4 of these or 8 of these mounted directly to the panel would do the same job for a fraction of the price if you don't mind a bit of soldering.

 

Cheers

David

[kevinlms]

1 minute ago, DavidB-AU said:

 

The capacitors appear to be marked 35V so that should be sufficient for 16V AC.

 

 

 

The documentation also says 16 Volts input, so I think it would be up to the job. Also good that the capacitors are a pair of 4700uF, some kits are a pair of 2200uF.

[Pete the Elaner]

39 minutes ago, Phaeton said:

This is the one I was looking at only because they also do a bank of 4 switches as cheap as I can buy 4 switches & can save postage https://www.ebay.co.uk/itm/RKcdu1-2x-4700uF-Dual-Capacitor-Discharge-Unit-CDU-Hornby-Seep-PECO-Points-Motor/182307855737?hash=item2a72651d79:g:3rcAAOSwNIFd52Ms

 

This looks excellent value.

I have made my own CDUs. The components cost almost as much as this complete unit & they don't look half as good.

[DavidB-AU]

8 minutes ago, kevinlms said:

The documentation also says 16 Volts input, so I think it would be up to the job. Also good that the capacitors are a pair of 4700uF, some kits are a pair of 2200uF.

 

I did notice they also had one with 4 x 4700uF rated for 24V AC input.

 

For £4.75 that's not a bad price for an off the shelf CDU. Building one yourself on a piece of veroboard would probably cost about the same.

 

EDIT: Snap.

 

Cheers

David

Edited February 19, 2020 by DavidB-AU

[Phaeton]

10 hours ago, DavidB-AU said:

That seems overpriced for what it does. 4 of these or 8 of these mounted directly to the panel would do the same job for a fraction of the price if you don't mind a bit of soldering.

 

Cheers

David

 

Confused by your comments David, your first link shows 10 pieces for £10.95, I only need 4 & £2 more than the made unit, the 2nd one are £1.95 each & I would need 8 so £15.60, am I missing something? Alan.

[DavidB-AU]

Switches always get used so it's cheaper in the long run. You can probably buy them individually somewhere local but that was the first thing that came up in a search. 2nd one are £1.95 for a pack of 10. Again you can buy them individually.

 

Cheers
David