Saturday, 16 March 2013

DC and DCC combined

I decided some months ago that the layout would be a hybrid, electrically speaking: allowing both DC and DCC locomotives to run on it.

Except for the matter of isolation, which I'll come to in a minute, the electrical circuitry for DC and DCC is the same.

Reminder:

with DC, the entire layout is live.
with DCC, the entire layout is live.

So, what's the difference?

Look at this diagram:

If the entire layout is live, why don't all 4 locomotives move at the same time and consequently CRASH when they get to the points?

DC

With a traditional DC circuit, one isolates the top 3 locos in the diagram by having a break in one of the rails  of each of their tracks - see wee red lines. That prevents those locos from moving.

In the case of the 4th loco, one bridges the break in the rail by connecting the two red wires, and thus the 4th loco moves, whilst the other 3, being electrically isolated, remain where they are.

DCC

With DCC circuitry there is a little computer chip in the locomotive. And, even if the track is live and electricity is reaching it, the loco will not move unless a command to move is sent to its computer chip. That command is sent through the rails from a special controller.

The loco does not need to be isolated in order to remain stationary - the DCC command system sends  the message "stationary" to its chip.

The isolation switch:

With DC, one  isolates or de-isolates the locomotive by disconnecting or re-connecting the red wires which bridge the break in the rails.


When the switch is in position B, electricity will flow to the loco and it will move.

So far, I have cut a break in the rails and installed the red wires. What I haven't done is joined the wires to an isolation switch.

Finger pointing to the break in the rail.

Close up of same.

DC and DCC combined.

At present, I have one  locomotive fitted for DCC, and 5 which are DC only. I no longer want to convert those 5 locos to DCC - far too fiddly a procedure.

But, by isolating the 5 DC locos, then the DCC loco can have free range to roam all over the layout under DCC command control. I'll use the DCC loco for shunting duties.

The DCC shunting loco
Then, when I want any of the 5 DC locos to move, I simply isolate the wee DCC shunter, switch the power source from DCC to DC - that will be a simple switching procedure - and then choose which of the 5 DC locos I wish to de-isolate. In the diagram below, the box marked X, will be the simple switch that will allow one to select either DC or DCC operation.


So, that's all clear as mud then!

It is the installation of the individual locomotive isolating switches and the installation of the switch to move between DC and DCC operation which is the next task.

Oh, and the purchasing of those switches AND a DC control power source; I've only got a DCC power source at present.

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Currrently listening to:


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Last night's dinner:

Take away chicken curry from Mr India's Balti and Dosa House, Glasgow.



Cost per head: approx £9.50

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Revelations etc

This new state of mind that I have so suddenly attained is very much in tune with the response to the psalm at this morning's Mass.

"Lord God, I take refuge in you."

And also, with Saint Faustina's exhortation:

"Jesus, I trust in you."


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Canvey Island:

Enjoyed watching the film  biography of Dr Feelgood, "Oil City Confidential", which was  on TV last night.




One of my ambitions is to wake up in a small bungalow on Canvey Island on a breezy Spring Saturday and walk out for the morning paper.
 

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