Since I rewired my layout I have provided for two controllers to be used.
Once the extension is built the fiddle yard will be up to 8ft away from the main operating position. To make operations easier I have introduced "cab control" where a train leaving the fiddle yard is under the control of the "main" operators controller.
A train travelling to the fiddle yard will be under the control of the fiddle yard operators hand held controller.
switching from one controller to the other is done manually by a switch on the main panel.
This of course requires two controllers. As I only have one (a Gaugemaster hand held) I decided to build another.
This brings me on to the main topic of this bog entry.
The circuit of my home brew controller is shown below.
It's a very simple design using only a few components but, the control of locos from this controller is stunning.
Because it is a closed loop controller using the back EMF of the motor as feedback the slow start and smooth running beats a lot of ready to use designs.
Note that there is NO smoothing capacitor, this is because the voltage needs to fall though the 0v point for the back EMF voltage to be measured. If a smoothing capacitor was fitted the controller would still work but, slow starts and smooth slow running would be impossible.
I take no credit for this circuit as it is quite a common type of control for small DC motors.
The controller (less transformer of course) is built into a small plastic box.
The method of construction though needs some explanation.
Instead of using a printed circuit or strip board I have used my "Ugly bug" technique using "islands" of PCB material with the components surface mounted on them.
the picture below shows what I mean.
I did however use a small piece of strip board for the rectifier diodes (seen on right hand side of box).
I find this method of construction very simple to do when just a few components are involved and this method lends itself to prototype development, allowing quick component changes when developing new ideas.
Here's a close up of the main assembly
And finally a picture of the finished and tested controller along side my Gaugemaster unit.
If anyone is interested in building one and needs more info ,I'll be happy to help.
Cheers for now