Lessons!
Entry posted by Richard Mawer
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Irritating got even more irritating!!! I made all the cuts in the track, installed 4 out of the five micro switches and even before I could wire them in (so the dead sections on the far rail were totally dead) the locos were still doing odd things. Another session in a darkened room and the reason for it AND the answer came to me. So I put in place Plan..... (Now what is it?) .....oh yes Plan D!! I soldered up all the damage I had just done to the track (!!!!!) and added just one more break, 2 wires and another centre sprung dpdt switch. Job done! How did I make such a mess!!
Big lessons:
try before you do 6 lots of stuff!
Think about back flows of electricity.
Don't test for electrical isolation or continuity with a loco on the track.
Expect locos and stock to bridge isolating breaks
Expect the unexpected.
Oh yes and don't blame sticky locos if you've not cleaned the track! I am sure I knew all that 30 years ago, but .........
Anyway, locos are now running with trains of coaches! It's been nice to see the 30 year old Castle perform for the first time in it's life and to see the new City being put through it's paces: a lovely loco!
At last I have been able to move onto the next phase: to make another MERG Servo 4 board and fix the servos to the double junctions. As you can see, the points have so far been held over with Blu-tac. You take the springs out of the tie bars if you are going to use servos, so you get the slow action change.
I have previously made a "servo 4" control board, as mentioned in an earlier entry in the blog. They are quite easy to make if you follow the instructions religiously. BIG LESSON: don't use either the 12v dc or the 16v ac feeds from Duettes to power them!! Not only did I blow up the main capacitor on the first board I made, but I had the same result with a board given to me by a friend! And that was after I changed from ac to dc following the first indoor firework display! Luckily another friend (aren't model railway clubs good!) has repaired both for me. So while I wait for them to come back, I've made another.
Each "servo 4" board controls 4 servos and you program the boards from a pc to set the two extremes of travel and the speed of change. The board remembers the settings and the servo then moves from one setting to the other by changing a simple on/off switch: easy AND realistic. With the electrical tests done and a new, regulated power supply (simple plug in 12 v dc) the board was up and running. Thanks to advice from some clever people at MERG I've modified the board a little to work on common return, but I am using a common return for all the Servo 4's that is separate from the power bus for the trains, to keep "noise" down on the power - no, I'm not 100% sure what that means either, but I'm told it stops the "chatter" or wiggling that sometimes can happen with servos.
I couldn't get the pc to operate the board and servos at first, but sought some more advice online from other MERG members. They are a helpful bunch. Although I got lots of advice I was still static and unresponsive -as it were. Then I put the software on my daughter's laptop and all was sorted!! The next issue was actually fixing the servos under the baseboard and linking to the tie bars on the points. My first attempt was the Evostick very sticky double sided tape pads to hold the servo in place and use a section of guitar string supa-glued to the armature crank to connect to the tie bar and provide an element of spring to hold the point blades hard over. The sticky pads worked (so far), but the guitar string was a disaster. Far too bendy. I ended up using piano wire bent through the armature and back on itself.
I've learnt another lesson as well. Even if you think the servos are set half way, they might not be. When you plug in the pc there is a chance they will travel right over and bend the wire, if not damage the point blades. Its going to be better to plug the servos into the board and the board into the pc, before fitting the armature to the servo and the servo under the points. We live and learn.
I had another project in mind for the Christmas break. I have to add horizontal rails along the front and rear of the high level junction main board so that the weight is spread. Instead of making whole lifting sections, the ends will be more open framed to allow holes to be cut and removable scenery so that the points into and out of the loops can be reached if needs be, but to allow for the correct alignment of the track, boards will be laid on the frames and the track fixed before the boards are cut around the formations. But that might have to wait.
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