CDUs

[challenger3802]

Does anybody use Capacitor Discharge Units (CDUs). Do they really improve turnout motor movement?

Also do you buy ready made or build your own?

Thanks
Ian

[Bob Hayes]

I have used them in the past, and have built them too, but they only work on twin coil switch machines. Their output pulse is very short and quite high and a turnout motor couldn't respond to it. Also, the pulse might damage the motor.
Bob Hayes

[rrinker]

I did, on my last layout that used twin-coil type swaitch motors, which was N scale about 25 years ago.
I built mine from "Practical Electronic Projects for Model Railroaders". A CD circuit is pretty simple and you have to be VERY heavy-handed with the soldering iron to damage the components used. That doesn't mean you don't have to use SOME care, but you can take your time and don't have to freak out because you left the soldering iron in contact with the part for more than 2 seconds. It's a good project for your first electronic assembly.
Circuitron has a ready-made one though, it should work equally as well.

In general - they work great. The principle is sound, and not only will they make your switch motors snap over with more authority, they will also help protect against burning out a coil if the button sticks or you hold it down too long. This was VERY critical in N scale. I never had a problem in HO, but when I built an N scale layout, suddenly I was burning coils fairly regularly, until I built the CD supply, then no more burned coils.

--Randy

[steveblackledge]

in the UK they are very comonley used to switch twin coil solenoid type machines, i use a CDU and the twin coil machines from a firm called Gaugemaster in the UK , (not far from you) http://www.gaugemaster.co.uk/ when you have a diode matrix to set turnout routing it takes lots of power to throw more than a couple of the twin coil units a CDU gives it a real Kick of power to set the points/switches. A CDU is not any use for slow motion switch machines as the power disipates very quickley

[Fergmiester]

I use them for about 15 Turnout solenoid machines. They are a good unit. One of my LHS's sells them. A local guy makes them. They go for about $30.

The unit that I have can throw two turnouts at once providing the turnouts are not stiff.

[rrinker]

Hmm, sounds like a business opportunity..... [:D]

[challenger3802]

A business opportunity indeed - and for those of us that spend all day soldering complex circuits, going into production should be an easy and profitable task!

Ian

[jrbernier]

I have one of the Circuiton units - It will snap at least 3 or 4 of the old Kemtron/Tenshodo type twin coil motors at once! I am presently replacing all of thise motors with Tortoise motors - I got sick and tired of the constant yearly maintenace on those old motors. No need for a CDU or 'snapper' and large power supply. A 'wallwart' power supply should handle the 12 powered switches on the layout once I am using the Tortoise motors.

Jim Bernier