Kato double crossover question

[emkay_777]

Hello Group (and Happy New Year)

 

Quick question about the Kato double crossover.  I have one that seems to have a 'lazy' point that sometimes doesn't seem to come all the way across.  Could this be because that the power pack is trying to throw 4 coils at the same time?  I have this crossover planned in a fairly inaccessible area so I need it to be reliable.  I would really like to put it on a capacitor discharge machine - can anyone recommend one?  Thanks,

 

Evan

[kvp]

I would say just add a larger capacitor (2200uF, >30V) parallel to the switch supply rail. (those power connectors on the side of your switches, check the polarity first)

 

Alternatively you can connect this cap series with the coils and ground and switch the other end between supply and ground.

 

All commercial circuits contain a variant of these two methods with different bells and wistles like lights.

[emkay_777]

I found what looks to be a laptop power supply - 19V, 3.4A.  Can this be used without any risk of burning out the coils?  I plan to use DPDT momentary center off toggle switches to throw the turnouts.  Thanks,

 

Evan

[inobu]

To answer your question...No. The power pack is not under a load or requires more power. There may be a simple issue at hand. Check the screws on the bottom of the cross overs or for dents or bows on the silver base. Most likely the slides are binding. Try to loosen and tighten the screws a little and check the sliding action.

 

There is a helper spring designed to drive the switch to its full open or closed position. If the silver base is too tight it can bind the switch. I would look at that first.

 

Inobu

[katoftw]

I would not push 19V into a 12V electrical device.

[kvp]

Yes. Personally i would just add a capacitor discharge circuit to it, but keep the voltage at or very near 12V. The 19V, 3.4A mentioned seems a bit too much, imho 12V and 1.5A should be more than enough in this case.

[emkay_777]

Thanks guys.  I think Inobu may be correct that something is binding as I tried another double crossover and it worked fine.  However, as much as I like the Kato turnout controls, they are rather bulky.  I think want to use the DPDT momentaries per this article by Fifer Hobbies:

 

http://www.fiferhobby.com/html/how_to_make_kato_turnout_contr.html

 

I guess I'll need to find a 12VDC power supply which should be no problem.

 

Going back to the double crossover, it is new and there doesn't seem to be any damage.  Inobu mentioned that there are springs to help it drive to position.  I am going to take off the back plate to see if I can see anything - I hope my next post isn't asking where I can get replacement springs . . . . .

 

Evan

[inobu]

The Kato controls are just a convenient solution but simple operation. Just a snap spring making monetary contact.

 

Momentary tactile switch do the same 

OSEPP - LS-00002   $6 for 12

 

These are breadboard ready.

 

Inobu

 

 

I should clarify something, additional circuitry is needed for a switch direction indicator. 

Edited January 12, 2016 by inobu

[kvp]

The tact switches are single circuit only and very low current. You can't drive a bipolar switch coil with them without extra circuits, not to mention the possibility of pushing the straight and diverging routes at the same time.

 

A spring loaded dpdt switch or a static spdt switch with a series capacitor is much better and easier to get right.

[cteno4]

Evan,

 

You might want to think about the capacitor discharge method. It's very simple and you can use inexpensive regular toggle switches that show the direction of the point. You can also add led indicators very easily as well. Kvp has posted some and if you pm me I'll put you in touch with someone who gives out a little how to set of PDFs.

 

The problem with momentary toggles is you can burn your coils if you lean on them too long. Coils just need a fast burst of power. Capacitor discharge does this very well,

 

Jeff

[inobu]

Slow we turn, step by step, we get closer to the BCD.

 

Inobu  

[cteno4]

Yes, solves a lot of issues!

 

Jeff

[tossedman]

Slow we turn, step by step, we get closer to the BCD.

 

Inobu

 

BCD?

 

Binary Coded Decimals?

[kvp]

It's a nickname for a bipolar capacitor discharge turnout control method that consists of a lone capacitor (for N usually between 1000 and 2200 uF) connected in series with the bipolar turnout coil and one end of this series circuit is tied to ground while the other end switched between ground and DC power (usually 12V). The capacitor acts as a pulse limiter as each charge and discharge cycle is time limited. Current is limited by the turnout coil connected in series. The switch for this circuit must be a continous one, which means there is no spring involved and no way to overheat the coils with a too long manual pulse. Also very easy to see the direction and add indicator lights. The component costs are also minimal (a capacitor and a switch) but some wiring is required.

[inobu]

Bipolar

Capacitor

Discharge

 

kvp explained it in detail.

[cteno4]

It is very neat, I love it. Basic wiring can be done with a terminal strip and just wires to the point and to the toggle switch in the board.

 

George Stilwell hands out a nice PDF on all the fun things you can do with the concept. Pm me if you are interested and I'll put you in touch with him. He does not want it handed around or posted, but he will email it to you. Know that pisses many off, but it's his work on those PDFs and I respect his wishes, he is a Very nice chap and super helpful.

 

I think kvp posted some reversed engineered diagrams here a while back on the basic circuit.

 

Jeff

Edited January 13, 2016 by cteno4

[kvp]

Found it: http://www.jnsforum.com/community/topic/1031-bcd-switch-control-circuit/

 

The 2200 uF is for the double crossover, for normal turnouts, 1000 uF should be enough. The first circuit is the basic version, the second is has led feedbacks and the third is showing how to connect multiple turnouts to be switched together.

[emkay_777]

Okay, I'm convinced.  BCD is definitely the way to go.  Thanks for all the enlightenment.

 

Evan

[emkay_777]

Okay, so it's been over a month since I ordered the caps from China and I've been chomping at the bit to try them out.  In the meantime, I have built and wired my board and have been studying how this circuit will work.  I am at a loss - in the top diagram, which is the simplest circuit, how does the capacitor charge itself when in the position shown?  Is that not like taking a cap and twisting the leads together and expect it to charge???  What am I missing?

signed Electronically challenged

[inobu]

Actually, the diagram is not depicting the correct idle condition. 

 

The line should be connected upward to the voltage.

 

+12 `````````````\,,,,,,,,,,,,,,,,,,,,

 

In layman terms this is what's happening.

              

The cap should be connected to the voltage.

Because of that connection the cap will "fill" itself with 12v.

When you push the button it will send the cap to ground.

This will cause the cap to "dump" the 12v into the switch.

causing it to operate.

Because the switch is spring loaded, it will return to the +12v and fill the cap once again.

Edited February 20, 2016 by inobu

[emkay_777]

Totally understand but are these not SPDT switches (not spring loaded push buttons?)

 

Sent from my Nexus 5 using Tapatalk

[kvp]

No. The cap is charged in one direction and discharged in the other. Since the coils are bipolar, both charging and discharging creates a pulse of DC power, but with opposite signs. Essentially you derive the signal wave of the DC switching ramps and create a pulse of power with + and then with - sign. The turnout has nothing to do with it, it's just a coil we use as a current limit and it does some physical work to dissipate some power. You can replace it with a bipolar formsignal or a resistor limited bicolor led and the circuit will still work.

[inobu]

Totally understand but are these not SPDT switches (not spring loaded push buttons?)

 

Sent from my Nexus 5 using Tapatalk

I does not have to be. The use of the toggle type switch is more so a position indicator similar to Kato's blue switch box. It is easier visualized with theory with momentary switches.

 

Inobu

[kvp]

No again. If you don't use a continous on-on switch, then the capacitor will slowly self discharge and there won't be enough power in it to generate the reverse direction pulse during discharge.

 

The operation of the bipolar capacitor discharge circuit is that the charging current switches to diverging, while the discharging current switches to straight.

 

Perhaps it's a bit easier to understand if you place the single coil turnout between the switch and the capacitor. The charging generates an in flowing current while the discharging an outflowing current giving the + and - polarities for the coil.

 

Momentary buttons and always charged caps are for the multiple coil, fixed polarity turnouts with 3 wires. Current Kato and Tomix turnouts are the single bipolar coil type with 2 wires. Inobu, please don't confuse people with fals information.

[inobu]

Here we go again......

 

It is called NC-O-C .......Normally Closed -- Open --  Closed ...  there are a series of switch configurations.

 

I tested this out when Jeff posted it in 2009. I think you started you reverse engineering in 2014. I designed a complete box for it but left it for JMRI. At that point I incorporated Digitrax into my designs which was about 2011 2012.

 

Remember what happened with that Digitrax thread that you added to also.

 

Inobu

 

 

Bottom line using your schematic will confuse the guys as the cap will never charge and be in the ready state. The BCD initial design is called Instant Charge Bi polar Controller. 

 

leakage........

Edited February 21, 2016 by inobu