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In a recent acquisition, I found in the box an Aristo Craft Reversing Controller, model ART-11090-02. One of my little projects was to set up a trolley line that went from one end to the other, sat for a few minutes, then returned. I am hoping this device may do the job. However, I have no documentation or any idea how to set one of these up.

First, will this do the job? If so, how do I hook it up?

If this is not the correct device, how do I set this type of operation up?

If this is not the right forum to ask, please point me in the correct direction.

Thanks,
Michael
 

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If that doesn't work for you, you can make your own for a couple dollars if you are handy with a soldering iron. I've made and use four with the included schematic.

See pics below:



 

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Discussion Starter · #4 ·
Posted By calenelson on 07/12/2008 11:26 AM
hey man this may help?
http://www.aristocraft.com/techinfo/manuals%20pdf/11091reversingunit.pdf

I had found this document before, but was slightly confused. It describes using insulated rail joiners and diodes, but only for the 11091 model. As mine is the 11090 version, I did not know what the difference between the two was. It looks like I'll just have to find some diodes and insulating joiners and try it out.

Thanks for the diagram, Todd. Maybe I'll give that a try if the box doesn't work out.


Thanks,
Michael
 

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Yup! That's what it does. There are 2 of those at the Chicago Botanic, one runs the cog railway and the other the ladybug.
 

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Discussion Starter · #7 ·
I discovered that after a little more research. The 11090 is a set which includes end bumpers and re-railers with built-in diodes. With the 11091, you get just the box. In my case, I got just the box, so I'll have to put my own diodes in. No big deal.

Thanks for all the comments.
 

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I'm interested in building a reversing unit from the schematic in this thread. Is there enough info describing the components to go to RS and buy them?
 

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Posted By chrisb on 09/30/2008 12:48 PM
I'm interested in building a reversing unit from the schematic in this thread. Is there enough info describing the components to go to RS and buy them?






If you know a bit about electronics - yes.

This schematic is just a basic multivibrator using a 555 timer. You can find that circuit on the net as well as the formula to calculate the values of the capacitor and resistor for any timing interval you want.

I would add a protection diode across the relay coil or the back emf could kill the 555 timer; also the relay has to be sensitive enough to be driven by the 555 timer and the relay contacts have to be robust enough to switch the track current.


All this unit does is switch track polarity at regular intervals, the interval being determined by the setting of the potentiometer.
 

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Does that mean that the circiut is reverses after a specific amont of time rather than when the locomtve clears the break n track and diode? Would this mean that slowing down the locomotve could cause it to reverse prior to getting to the end?
 

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Yes -

The circuit is extremely basic but I think it will work fine if you set it up correctly.

The 555 timer is configured as a multivibrator with a very low pulse rate - so the relay will switch and change polarity based on the RC time constant of the 200 mf capacitor and the setting of the 500K pot.
That means you can agjust the pulse rate.
The idea is to make the pulse rate a bit longer than the time it takes the train to go from one end to the other - once the loco passes the diode at the end of the track it will stop because the diode will block the current. As soon as the timer reverses the track polarity, the diode will conduct and the train will head back in the opposite direction where the whole thing repeats itsel with the other diode.

So you set the switching time of the unit equal to the time it takes to travel from one end of the track to the other PLUS the time you want the engine/train to stop at each end before reversing and travelling back. Does everything it's supposed to do with a very simple circuit - but of course if the relay switching and thus the reversal happens before the loco reaches the diode section, then the train would reverse immediately which is not exactly good for the engine.

You can get more details here for example:
http://delabs-circuits.com/cirdir/theory/gates/doc00019.html

Rough calculation indicates the switching time of the relay can be adjusted from about 6 seconds to about 75 seconds.
 

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Posted By krs on 09/30/2008 5:28 PM
Yes -

The circuit is extremely basic but I think it will work fine if you set it up correctly.

The 555 timer is configured as a multivibrator with a very low pulse rate - so the relay will switch and change polarity based on the RC time constant of the 200 mf capacitor and the setting of the 500K pot.
That means you can agjust the pulse rate.
The idea is to make the pulse rate a bit longer than the time it takes the train to go from one end to the other - once the loco passes the diode at the end of the track it will stop because the diode will block the current. As soon as the timer reverses the track polarity, the diode will conduct and the train will head back in the opposite direction where the whole thing repeats itsel with the other diode.

So you set the switching time of the unit equal to the time it takes to travel from one end of the track to the other PLUS the time you want the engine/train to stop at each end before reversing and travelling back. Does everything it's supposed to do with a very simple circuit - but of course if the relay switching and thus the reversal happens before the loco reaches the diode section, then the train would reverse immediately which is not exactly good for the engine.

You can get more details here for example:
http://delabs-circuits.com/cirdir/theory/gates/doc00019.html

Rough calculation indicates the switching time of the relay can be adjusted from about 6 seconds to about 75 seconds.



You are correct on all accounts.

What is not mentioned is that with this circuit, using a readily available 6 volt relay (that can easily handle the amperage of a train though its contacts), you need to be running the trains at a minimum of ~8 volts. I always run my trains at 10+ volts so this was not an issue when I came up with the circuit. If you want to run your trains with less than 7-8 volts, you would have to modify the circuit with an additional power supply tap to power the electronics, in addition to the power that actually feeds the rails.

If you want to increase the timing interval, you can increase the values of the capacitor and/or pot.

Some 555 chip/relay combinations can be "finicky" where the chip won't fire, or sometimes misfires. This can usually be fixed by putting a "backward" diode acoss the relay coil. It really depend on the relay and chip manufacturers specifications.
 

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You want the diode across the coil, not the contacts;)
 

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Posted By Torby on 09/30/2008 7:00 PM
You want the diode across the coil, not the contacts
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Correct. Sometimes I also find it helps to put a capacitor here or/also. In the case of a capacitor, I usually find the value is not critical, and can be on the order of 20 - 100 mfd. In this case you need to be sure that you have the correct + and - in accordance with the relay coil (not reversed like the diode) and that the capacitor voltage is higher than the relay voltage.

There is actually about a 1.5 volt drop from the chip to the relay so the relay really gets about 4.5 volts. This is enough for most 6 volt relays. (I've used literally a couple dozen driven off 555/556 chips). If you can find them you could even use a 4.5 or 5 volt relay, providing the contacts can handle the current of the trains.
 

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Toddalin -

I must admit I didn't realize that was your circuit - I thoght it was the schematic of the Aristo unit. I just looked at the diagram - didn't read the text.

But as a former commercial designer, I'm curious about a few things.

1. Why do you think a back-emf diode is not required across the relay coil? The 555-type timers I'm familiar with don't provide an internal protection diode and without back-emf protection and the inductive load, the output transistor won't survive for long.

2. Pin 4 and 5 in your circuit are not connected. If not used, pin 4 should be connected to the positive supply and pin 5 should be connected to ground through a 0.01 mf (microfarad) capacitor to eliminate electrical noise.

3. I think a 220 mf capacitor would be more appropriate for the timing capacitor simply because 220 mf is a standard value where as 200 mf is not.

And finally - since it looks as if people want to build this circuit for their own railroad, it would be helpful if you took the time to list the specific components required with the appropriate RS part numbers.
 

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Posted By krs on 09/30/2008 10:10 PM
Toddalin -

I must admit I didn't realize that was your circuit - I thoght it was the schematic of the Aristo unit. I just looked at the diagram - didn't read the text.

But as a former commercial designer, I'm curious about a few things.

1. Why do you think a back-emf diode is not required across the relay coil? The 555-type timers I'm familiar with don't provide an internal protection diode and without back-emf protection and the inductive load, the output transistor won't survive for long.

2. Pin 4 and 5 in your circuit are not connected. If not used, pin 4 should be connected to the positive supply and pin 5 should be connected to ground through a 0.01 mf (microfarad) capacitor to eliminate electrical noise.

3. I think a 220 mf capacitor would be more appropriate for the timing capacitor simply because 220 mf is a standard value where as 200 mf is not.

And finally - since it looks as if people want to build this circuit for their own railroad, it would be helpful if you took the time to list the specific components required with the appropriate RS part numbers.



1) Of the literally 2 dozen of these I've made, only a couple have required me to add the back-emf diodes for proper, long-term operations. If it ain't broke, why fix it?

2) Of the literally 2 dozen of these I've made, I've only found it necessary to add the 0.01 cap on pin 5 in one case and that was for an occasional glitch problem. About 8 out of 10 schematics I've reviewed omit these parts too.

3) As I noted, the part values aren't critical. I use parts from cannabilized VCRs, TV sets, DVD players, etc., and Internet surplus sales, so I gets what I gets.

All component values (except the relay which is obviously 6 volts as mentioned) are included in the schematic. If the named part is not in RS stock, use the next "bigger" value and that should do the trick.

These are the circuits that drive my module for the Del Oro Pacific. They use 9 556s and one 555. None have the reverse diodes or 0.01 mfd caps. These drive 10 of the 6 volt relays.

 

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Thanks for your reply toddalin -

Reminds me of a saying we had in our electrical engineering group: "Design marginal circuits and fame and fortune will be yours"

As to components used, you don't have any specs on the bridge rectifier or the voltage regulator for instance.
Will 1N914 diodes do for the bridge rectifier (after all they are cheap and I have almost a 100 of them in my component box); and what about a 78L06 6 volt regulator, I have a few of those lying around also.
 

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Without the diode, my temperature controler made of an atmel processor goes haywire any time it turns off the relay.
 

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Posted By krs on 10/01/2008 12:31 PM
Thanks for your reply toddalin -

Reminds me of a saying we had in our electrical engineering group: "Design marginal circuits and fame and fortune will be yours"

As to components used, you don't have any specs on the bridge rectifier or the voltage regulator for instance.
Will 1N914 diodes do for the bridge rectifier (after all they are cheap and I have almost a 100 of them in my component box); and what about a 78L06 6 volt regulator, I have a few of those lying around also.

Schematic does say to use a 6 volt positive regulator. To me, a rectifier is a rectifier is a rectifer and even the smallest of these are rated at 1 amp and will have plenty of capacity. You can use four 1-amp (4000-series) diodes to form the bridge.
 
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