Friday, 11 May 2012

Penmaenpool MPD progress, odds& ends

All the track is now laid, and power feed droppers connected.

I haven't taken any pictures yet because no doubt you have seen 00 gauge track and turnouts before.

The points are home made copper clad sleepers and bullhead rail, so need some thing a bit less stressful than solenoid point motors to operate them.

I have chosen to use Fulgarex slow action motorised switch machines, unlike the Tortoise type motor the action is a linear movement rather than a fulcrum wire used on the Tortoise motors.

To operate the switch blades via the tie bar I came up with this home made device. Knocked up in about an hour on the workbench.
The lever needs to be drilled out at the correct position to reduce the throw of the Fulgarex.
The switch blades only move a few mm whereas the Fulgarex has a stroke of 8.5mm
The electrical connector block inserts on the slide bar act as mechanical limits to prevent damage to the point tie bar and blades.

The materials used are brass strip,  tube, wire, 8BA pin and nuts and a piece of copper clad PCB material.
Also in the picture can be seen a simple "bell crank" also made from PCB material and a 10BA pin and nuts.
The idea is to turn the drive to the TOU through 90deg to allow the Fulgarex unit enough space under the baseboard. Any "over drive" from the Fulgarex will be absorbed by a Z loop (as opposed to an omega loop)

Reading up on the internet about using Fulgarex motors I found that although designed for 12v DC operation they are a bit too fast at that supply voltage.Most users recomending 9V operation. Added to this that my transformer gives me over 22V DC after rectification and smoothing then they would certainly whizz across! Not what I wanted really.

I plan to overcome this by using a simple electronic circuit to control the motor voltage and thus the change over speed of the switch blades.
Using a commonly used circuit and a few components from my electronics odds & ends box I knocked this small circuit board.
I can now set the speed of the point motors to a reasonably gentle change over speed.

A far cry from the Peco points on my existing layout Pen Y Bont, where old H&M point motors slam the switch blades over at Mach 1!

I'm still waiting for the Fulgarex units to arrive from DCC suppliets. Once I get them fitted and working I'll update this entry.

Cheers for now

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