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webbcompound
Joined: 25 Nov 2008
Posts: 3
Location: UK
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 Posted: Tue Nov 25, 2008 8:49 pm Post subject: Better Controll? |
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I thought I'd seen a thread on a blog or board about building a better controller for T. Not here, and you'd think it would be easy to find as there arent that many T gauge sites, but I cant find it. Any ideas?
the other possibility is to run lots of motor units in the same train. OK if you are modelling main line but my trains will only be two or three coaches.
Jon Price
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Jon Price
building Epoch III Thuringia narrow gauge feeder for Z layout |
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David K Smith
Chief Cook and Bottle Washer
Joined: 03 Sep 2008
Posts: 435
Location: New Jersey, USA
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Chris333
Joined: 25 Sep 2008
Posts: 74
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| Posted: Tue Nov 25, 2008 10:55 pm Post subject: |
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David found this throttle:
http://www3.sympatico.ca/kstapleton3/851.HTM
I e-mailed him and found the Z scale version outputs 7.6V, N scale is 9V, and HO is 12V. They require at least 10VAC power supply.
Lets say you buy the Z scale version. Doesn't that mean you are bursting 7.6V to the motor?
Anyways I ordered all the components to build this:
It runs off of 3vAC
I'll let you know how it works. |
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David K Smith
Chief Cook and Bottle Washer
Joined: 03 Sep 2008
Posts: 435
Location: New Jersey, USA
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| Posted: Wed Nov 26, 2008 1:51 am Post subject: |
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| Chris333 wrote: | David found this throttle:
http://www3.sympatico.ca/kstapleton3/851.HTM
I e-mailed him and found the Z scale version outputs 7.6V, N scale is 9V, and HO is 12V. They require at least 10VAC power supply.
Lets say you buy the Z scale version. Doesn't that mean you are bursting 7.6V to the motor?
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Yep. Although I'm thinking it could be regulated at the output... voltage regulator, or maybe some zener diodes...
I'll be intereted to see how you make out with Allard's.
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—David
http://www.t-gauge.net/
http://1-450.blogspot.com/ |
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webbcompound
Joined: 25 Nov 2008
Posts: 3
Location: UK
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| Posted: Wed Nov 26, 2008 7:45 am Post subject: better controller |
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Thanks for this excellent stuff guys
Some of this even looks do-able for me (a visit to Maplins and a purchase of a breadboard and components will be a new experience)
I have a ZTEK, but the main reason I dont like it is it uses batteries, and Id rather use a mains transformer (more ecological, and the mains is less likely to run out)
I'll keep watching for more advice on improved controllers.
On a different topic (sorry not good for boards) I just got a christmass card from Plaza Japan with a nice Japanese high speed train on it.
Jon Price
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Jon Price
building Epoch III Thuringia narrow gauge feeder for Z layout |
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Chris333
Joined: 25 Sep 2008
Posts: 74
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| Posted: Thu Dec 04, 2008 12:37 am Post subject: |
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Well I built the circuit I post above and get nothing out of it. I just love spending $50 and throwing it in the garbage! 
I got a transformer that puts out 2.9VAC, but when I connect it to the circuit nothing comes out the other end.
Guess I should be happy no smoke was created. |
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zomer
Joined: 03 Nov 2008
Posts: 124
Location: Victoria, Australia
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| Posted: Thu Dec 04, 2008 12:53 am Post subject: |
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If your throwing it in the bin anyway shouldnt you wish that you at least got 'some' smoke? 
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Victorian T Gauge Blog
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pray59
Joined: 05 Sep 2008
Posts: 88
Location: Fremont, CA
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| Posted: Thu Dec 04, 2008 6:08 pm Post subject: |
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| Chris333 wrote: | | Well I built the circuit I post above and get nothing out of it. I got a transformer that puts out 2.9VAC, but when I connect it to the circuit nothing comes out the other end. |
I am no electronic design guru, but if you built the above circuit, look at dropping .7v positive, and .7v negative from the bridge diodes where AC enters. Thats 1.4V total.
Now you have a thyrisistor, which I do not fully understand except the part of the symbol that resembles a diode, meaning it too must drop at least .7 volts to operate. I suspect the Thyristor is a gated diode, using a potentiometer to throttle the barrier region of the diode, like an FET.
That's 2.1 volts total dropped out of your 2.9V transformer, leaving too little power to open the gate. I would use a 6VAC - 9VAC transformer and measure again. Once you find the AC power you need to operate the circuit, just crank it all the way up, measure the output voltage, and replace the 1K resistor on the thyristor gate with a value that will limit you to 4.5v.
To do that, use your meter to meaure the speed pot resistance required to get 4.5 volts, and change out the 1K resistor with a value that adds up to the total resistance of the pot and 1k resistor at 4.5v. Example, the pot measures 3K plus the 1K resistor, so use the next size up resistor, 4.7K.
-Robert
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Chris333
Joined: 25 Sep 2008
Posts: 74
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| Posted: Thu Dec 04, 2008 8:46 pm Post subject: |
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I don't understand electronics, but can built it using the schematic.
Armand told me I needed to drive the circuit with 3VAC. I wanted to replicate his results so thats what I did.
But the transformer I used is 6VAC that I wired to get 3 out of it:
So I can try it at 6V and see what happens... |
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pray59
Joined: 05 Sep 2008
Posts: 88
Location: Fremont, CA
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| Posted: Thu Dec 04, 2008 9:03 pm Post subject: |
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Yes Chris, use the 6V and see what you get out. Also, I am not sure what TR1 does, but you might try moving that trim pot to it's center position.
Use the top black and red with the top blue and yellow on your transformer too.
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Chris333
Joined: 25 Sep 2008
Posts: 74
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| Posted: Thu Dec 04, 2008 11:18 pm Post subject: |
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OK now at 6VDC I get at least something out of the other end. 1.73VDC with the speed up and 1.45VDC with the speed down. This doesn't make sense to me. Shouldn't it read 0 when turned down?
On top of that I can't get a LED to light up even though it shows 1.7VDC. I know LEDs have polarity and I tried it both ways.
Back to the lab.  |
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David K Smith
Chief Cook and Bottle Washer
Joined: 03 Sep 2008
Posts: 435
Location: New Jersey, USA
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| Posted: Thu Dec 04, 2008 11:43 pm Post subject: |
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| Chris333 wrote: | OK now at 6VDC I get at least something out of the other end. 1.73VDC with the speed up and 1.45VDC with the speed down. This doesn't make sense to me. Shouldn't it read 0 when turned down?
On top of that I can't get a LED to light up even though it shows 1.7VDC. I know LEDs have polarity and I tried it both ways. |
With PWM, the voltage of the pulses are the same at any setting; the slight difference your meter displays is a result as it averages out short pulses and slightly longer pulses into some kind of mean voltage (in the same way it would read AC voltage as RMS of the sine wave, but it won't display the peak voltage). From the sounds of things, the pot is still leaking enough voltage into the circuit to keep it firing even at zero, and it's just putting out a kind of smallish pulse under all settings (maybe roughly equivalent to a range of 30% to 40% of the throttle), so you may need to do some fiddling with it and the trimmer.
What you really need is a scope, unfortunately...
As for the LED, 1.7VDC might not be enough, especailly as it is pulsed, with likely a fairly short duty cycle; some won't come on until it gets at least 3V. You will need even more voltage if you have a load resistor, which you should have in an LED circuit anyway; elsewise it acts like a near dead short in one direction.
P.S. What is the value of C1 you are using? The diagram shows 10nF--not an especially common value.
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http://www.t-gauge.net/
http://1-450.blogspot.com/ |
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Chris333
Joined: 25 Sep 2008
Posts: 74
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David K Smith
Chief Cook and Bottle Washer
Joined: 03 Sep 2008
Posts: 435
Location: New Jersey, USA
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| Posted: Fri Dec 05, 2008 1:25 am Post subject: |
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Did you try contacting Armand again? I know he's not willing to build one for you, but maybe he'd be kind enough to try and help out.
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—David
http://www.t-gauge.net/
http://1-450.blogspot.com/ |
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pray59
Joined: 05 Sep 2008
Posts: 88
Location: Fremont, CA
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| Posted: Fri Dec 05, 2008 2:59 pm Post subject: |
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What happens when you adjust the trimmer from one side to the other?
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