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Using T Gauge within O Gauge

Postby Switcher102 » Tue Aug 16, 2016 1:02 pm

I believe there are a few modellers out there who use T gauge to represent one of the smaller gauges that we have in the real world. Well this is my effort so far in that field. My scale is O scale and within that scale T gauge represents 5 inch gauge. I have had a go at making a coach for that gauge and this is shown in the photo. Also included in that photo is a representation of 15 inch gauge (the green Britannia - N gauge) and 2 foot gauge behind that, and then standard gauge.

Now, the thing is, I have converted to Battery Powered Radio Control (BPRC) for all my stock, and do you know what? I reckon I can convert T gauge to BPRC. Because I am using it to represent 5 inch gauge, and my driver has to sit on a wagon behind the locomotive, that wagon can be permenantly attached, and as you can see in the photo it will be bigger than the T gauge stock. Electronics is getting smaller and smaller these days and there is a receiver small enough to fit inside such a wagon, and if button batteries will be sufficent I reckon it can be done. I have a very tiny reed switch and equally tiny magnet that can switch it on, and all that can fit inside such dimensions. I am also aiming to go one step further and make the driver's head turn for when going backwards ..... eeeek!

A tall order perhaps but I've got it all planned and I'm going to have a go. One of the big beauties I like of BPRC, apart from no track wiring, is the fact that you get constant power. There's no stuttering, no hesitation over dirty track, you can go as slow as you like over points, and go anywhere on other layouts.

This use of T gauge offers another avenue for sales, except I doubt if my efforts will persuade other O gauge modellers to have a go. Most O gauge modellers find even N gauge too small to see and handle, but you never know. I think T gauge is more likely to be used by OO/HO modellers, in which I think T gauge represents 15 inch gauge, and I think the Garden Motor Car is for that use is it not? Anyway, watch this space for O gauge's use of a such a wonderfull fascinating gauge.

Rich
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Re: Using T Gauge within O Gauge

Postby mattinair » Tue Aug 16, 2016 10:15 pm

Radio control neat!
There's a guy on Tgauge.com 's facebook page who's doing a 1/450th scale Godzilla attacking a T gauge train :o .......The tiny size makes so many things possible... :D
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Re: Using T Gauge within O Gauge

Postby mattd10 » Wed Aug 17, 2016 9:27 pm

I'll be following this with interest and I love the idea of using T for narrow gauge but have never gotten around to it myself! Best of luck with it!
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Re: Using T Gauge within O Gauge

Postby Switcher102 » Thu Aug 18, 2016 7:48 am

That's good Matt, thanks. Ordered my first T gauge locomotive yesterday, the Garden Motor car, 2 metres of wider sleeper flexi track, and a pack of adjustable chassis. Long way to go yet, you know how it is, more than one project on the go at the same time. Next thing to get is the radio receiver and battery. Look how small you can get receivers these days:- http://www.deltang.co.uk/rx31b.htm .

Incidentally, if anyone does fancy converting T gauge (as standard gauge, not what I'm doing) to wireless control well, after you've stopped laughing, have a look at a new thread I will post shortly. I was typing it out here but actually I think the subject deserves its own thread.

Rich
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Re: Using T Gauge within O Gauge

Postby Switcher102 » Thu Aug 25, 2016 7:26 am

Received my first T gauge locomotive yesterday. I don't have a T gauge controller because as mentioned above I am aiming to convert it to battery powered radio control but I would like to test it. I am thinking that it would be fine to test it with one of these … http://www.gaugemaster.com/item_details ... gemaster+D …. as long as I don't turn the dial up high.

My way of testing a locomotive doesn't involve just wacking the dial up and get it going, so connecting it to a suitable battery would not be a sufficient test for me. I need a potentiometer because my main concern when testing is to see how accurately it starts and stops. I would only need to simulate about 30mph scale speed, if even that. I have a multimeter so I could connect it to the tracks and watch the voltage. Is there anything else I should be concerned about when testing it with the Gaugemater controller linked above?

Rich
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Re: Using T Gauge within O Gauge

Postby mattd10 » Fri Aug 26, 2016 12:02 pm

I would be wary, as the commercial controllers run off of 3xAA batteries or a low voltage transformer. I don't know what the current output of the T gauge controller is but I suspect its lower than the gaugemaster and that is going to be the issue. I don't have my stuff to hand but I'm sure someone can advise the current output of a standard controller to see if it's compatible. In the past I've used a cheap PWM motor controller from ebay but powered it with 3 AA batteries so I know I won't blow anything or cause any damage!

Cheers

Matt
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Re: Using T Gauge within O Gauge

Postby Switcher102 » Sat Aug 27, 2016 10:50 am

Thanks Matt. I'll give that a miss then. I'll wait untill I get the radio control equipment, and ask Alan at T Gauge Central about the current limit.

Accurate movement is an absolute MUST for me in modelling and I am really impressed with what T gauge can do. I found this:- https://www.youtube.com/watch?v=xTK3C62yY2g

Now that is a great video to advertise T gauge ….. still needs a flywheel in my opinion but that is terrific movement for such a small scale. It's better than many O gauge locos. Don't know what's with the spooky music in that video, it sounds as if it's coming from Planet Zog ….. or should that be Planet T? :)

Rich
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Re: Using T Gauge within O Gauge

Postby martink » Sat Aug 27, 2016 1:52 pm

Back when I started with T, I did some measurements of the motor units' electrical characteristics. Each motor unit pulls 20-25mA at full speed, plus another 5mA or so if it has LEDs. That is running on the standard 4.5V battery-powered blue-box PWM controller. As you can see from the oscilloscope trace, the PWM drive pulses from that unit are just over 4V high.

Image

I choose to run mine with 5.5V pulses but with a maximum duty cycle of around 80%, so the average voltage is limited to that same 4.5V but gives me better low speed starting & stopping.

A conventional controller designed for larger scales running off its normal power supply will produce peak voltages of 15V or more, even if you keep the speed knob turned way down. VERY bad for this sort of small motor, and catastrophic if you accidentally bump the control knob. The Gaugemaster controller you linked to has an built-in mains power supply, so you CANNOT prevent or change that. If it is designed for O gauge, then we are talking 20V peaks. If you use a controller with an external power supply and connected a 5 or 6V AC supply, you would probably be safe enough (no promises though), but could not expect any sort of decent slow running - that would certainly be outside the controller's designed operating range.

In practice, the main limitation on slow speed running in T is the unreliable connection between the track and the wheels. A battery-powered system would bypass that and any compact motor controller that you could squeeze into such a model will have to use PWM since that is the only viable way to do it in the available space.
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Re: Using T Gauge within O Gauge

Postby Switcher102 » Tue Aug 30, 2016 9:29 am

That's usefull info Martink, thanks for that. I'm not familiar with oscilliscope readings. Shouldn't there be a zero point somewhere? I can't see it. I can see that each square is 1 volt. Would you call that reading shown as a 50% duty cycle because there's as much high voltage in width as low? To be an 80% duty cycle am I right that the high voltage reading would show as wider, and the low voltage reading would be 20% of that width?

Being a starter in electronics I've got my work cut out trying to decide which receiver to buy out of this lot http://www.deltang.co.uk/. I am a member of MERG so I can ask questions on their forum aswell. Thank you.

Rich
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Re: Using T Gauge within O Gauge

Postby martink » Thu Sep 01, 2016 11:23 am

That is a very interesting site. I've been thinking for quite a while now that battery+radio is the way forward for model railways, but alas not quite yet for T gauge. For my N gauge stuff though.... hmmm....

For the 'scope trace, the zero point is the small "2->" in the bottom left - this indicates the zero voltage level for channel 2 (blue). The pulses are about 4.2V high, and the duty cycle is about 45% (on 45%, off 55%), which gave a reasonable speed for the HST. You can also see the back-EMF - between the drive pulses, the motor is acting as a generator and brake, and is so light that you can actually see it slowing down after each pulses.

The point I was trying to make was that the voltage from a single Li battery (4V or so) is just right for T. That should be no surprise, since our motors are borrowed from mobile phone technology which uses just that sort of battery. Our only real problem is mounting them in the tiny bodies. With miniature trains in O scale, that really is a feasible option for you. Your best bet would be to contact that company and see what they suggest.
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