Monday, February 13, 2012

Flicker Free Omission

In my last post I described a simple method for adding flicker free lighting to the Austrains FS BS coaches. I did however leave out a zener diode Pt no. IN4733. The diode needs to be placed across the capacitor terminals, reverse biased (black line connected to the positive capacitor terminal). This zener clamps the capacitor input voltage to 5.1 volts. After sitting there thinking about things one day I happened to remember the capacitors 5.5 volt input limit and the fact that without the diode the super cap will not last long with track voltages above 6.9 volts.

Once I complete the three pack of coaches I will draw a circuit diagram and take a few pictures.

Sorry for the omission. I was so excited about how simple this mod was to achieve I over looked an important fundamental.

Thats it for now,


Monday, February 6, 2012

FS & BS Coaches

For the last couple of days I have been in an experimental mood. I bought two packs of Austrains T&R FS/BS coaches a few weeks ago and have not been very happy with my purchase. There have been some great modification articles already written and I intend on doing most of the procedures within however there are still a few issues not covered that I want to resolve.

Anyway I decided to have a go at building some working diaphragms. There was an article in AMRM, I think (sorry to the author) on converting the old powerline diaphragms by cutting the rubbing plate part of and then building up a telescoping section with styrene. I used this method and carefully cut the Austrains diaphragm up. They were quite easy to build and by adding a piece of bronze wire at an angle across the pivot wire they are nice and springy (is that a word?) I have added a few photos of the finished but unpainted attempt. I still have many more to build so I will take some construction shots for a later post.

This method allows the diaphragm to be simply clipped back into place and no coach body work is needed. The next challenge however is altering the position of the couplers so as to get a nice close coupled train. If anyone has some ideas on how to change the coupler spacing I would love to hear them. I am using short shank, scale head Kadees and they are still set too long. I have a few ideas but they involve a fair amount of work.

That not all folks! As the coaches do not roll very well, due to sticking brakes I decided to fit 88 wheels. Problem solved they run along very well now. As the replacement wheel sets do not have a split axle a cut in the steel weights is required thus utilising each bogie for the opposite polarity (insulated wheel on opposite sides). This however leaves only half the amount of pick up available for the lighting though.
After looking over the lighting circuit board I noticed there is a 100 ohm resister on the input, a bridge rectifier, a couple of caps and a voltage regulator. This has all the makings of a flicker free circuit minus the super cap! I quickly de-soldered a super cap - I had one on a circuit in my draw and clipped it over the output of the bridge rectifier (make sure you get the polarity correct). I bench powered the circuit and wouldn't you know it after cutting the power the LEDs remained lit for just under ten minutes! Who needs all wheel pick up! The super cap I used was a little large in capacitance so I will put an order into Jaycar for a couple of 0.047f types. At around $4.00 a cap I think this is a cool, easy mod. The cap will most likely have to have leads fitted and then secured in the ends of each coach. I am not sure how this circuit will behave under DCC. It should be fine as the input to the super cap has been rectified. Would love someone with DCC to experiment.

That's it for now. Hope someone can have some fun with this. BTW I have only just completed the flicker free mod and will test it out over the next few days for reliability.


Thursday, February 2, 2012

How to make a RTR model into a kit!

Well as the title alludes, I have been busy turning a couple of perfectly good Lima TAM cars basically into kits.
As with the Casula RUB cars I thought there may be a better way to flush glaze the TAMs rather than using the vacuum formed windows available.
To cut a long story short I basically used the same method as the RUB cars and milled the back of the window recesses. To achieve this on the Lima TAM I had to split the coach up the middle. I used a steel mini saw blade mounted in the mill. The cut it produces is incredibly fine while barely produced any shavings. The TAM will glue back together with hardly a difference in its original width.
With the coach in two milling could commence on the window recesses.

Here a few pictures of the process. Once the coach has been glued back together hopefully work will commence on the underframe and roof.

That's it for now.