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Post by Deleted on Jul 8, 2017 12:55:07 GMT -5
Thank You Mark. In fact a "filtering" capacitor could be a buffer (that's approximately what happens with Your Rokuhan controllers). With the Kato system, the capacitor is charged directly through the coil. The only solution, as You wrote, would be a BIG filtering capacitor connected to the output of the power supply, charged through a resistor. But it's not necessary : a 7.5V, 6A switching power supply costs less than 19 Euro (less than a CHEAP freight car). So, where would be the advantage ? And I would have to wait several seconds before I could flip other turnouts ; this will not happen with "direct" power supply, I think I can flip turnouts every 0.5sec.
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Post by popejon on Nov 12, 2017 21:08:39 GMT -5
I found your forum and this seems to be exactly the solution I am looking for. I'm just learning about how DC works while wiring my control board and blocking out sections of track. So at first the Kato circuit made no sense to me. But learning more about capacitors and what they can do, the circuit eventfully made sense. I finally just got the chance to replicate it but I used 1500uf with 6 volts of regulated DC power instead of 7.5 volts with 2200uf. I wired it just like a drew it in the attached pic. It worked beautifully! But then I noticed a very high faint pitch sound after the capacitor was charged and the turnout was throne. The sound went away as soon as I let the capacitor discharge in the opposite direction to throw the turnout in the opposite direction. Went back to the electronics store and asked the knowledgeable person who had helped me find all the parts I needed for this circuit what the problem might be and he said that capacitors can leak. So how did you get around the leaky capacitor factor or is there something else I'm doing wrong that's causing it to leak? Thanks, -Jon
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Post by Deleted on Nov 13, 2017 1:18:21 GMT -5
I didn't make anything special and never noticed any sound ; I only put 2 "freewheel" diodes to the switch to protect it, but I don't know if they are really useful and I think they have no relation with Your problem ... I think the sound comes from Your power supply, it is "not enough" filtered and You hear the residual ripple (at the frequency of the "switching" unit in the supply) in the turnout's coil, the capacitor gets alternatively partially charged and discharged ; DANGER, this can destroy Your turnout by overheating, because there is a residual (alternating) current ! If You have access to a scope (even an old analog model) You can monitor the power supply's output. I tested with a lab power supply and a table top switching power supply looking like this with a voltage selector (my 3 A version is no more in stock) and had no issues ... An additional filtering via a capacitor could be a solution, but I wonder if this capacitor, discharged at startup and behaving like a short circuit, would not cause issues to Your power supply ! Perhaps You could try a diode (1N4007) between the supply and the switch (anode to Vcc of supply, cathode towards the switch), to avoid the "backwards" discharge current ; warning, this causes a loss of about 0.6 V. PS : 1500uF, not 2200, is the optimal value with 7.5 V to ensure reliable operation !
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Post by popejon on Nov 13, 2017 17:59:05 GMT -5
I'll have to go back and try some of your recommendations.I was wondering if it had something to do with the power supply. Its a regulated DC power supply that I can switch the voltage on. I didn't strip the connector at the end. Instead I inserted the turnout power supply wires into the female plug holes.
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Post by Deleted on Nov 14, 2017 0:00:25 GMT -5
I made my tests the same way, plugging the wires into the holes, I think this can't cause the problem if the contact is good (bend once the bare ends of the wires before inserting them) ... First, try the solution with the additional diode and switch perhaps the voltage "up", don't forget the 0.6 V loss ... The optimum values that I found out are 7.5 V (at the switch) and 1500uF. Another question : How many Amperes can Your supply deliver ?
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Post by Deleted on Aug 22, 2018 13:58:37 GMT -5
Now my turnouts are installed in place ; last time I thought that 7.5 V with a 1500 to 1800 uF capacitor are enough ; unfortunately it isn't ; it works with MOST turnouts, but SOME need a 12 V pulse to switch reliably (otherwise they don't reach fully the stop and cause derailments) ; finally I will use 12 V and perhaps decrease the capacitors to 1200 (or 1000 ? ) uF, so the total amount of energy through the coil will stay about the same, and this should not cause any damage ; and every turnout is not activated more than once or twice during a lap of 2 or 3 minutes, so I don't fear overheating ...
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Post by Deleted on Sept 15, 2018 14:02:34 GMT -5
I tested one turnout with a power supply of 12 V, 3A and a capacitor of 1500 uF . I did a test which one "should not do" : I switched 20 times "back" and "forth" (40 movements), with less than 1 s pause between two successive movements. I didn't notice any warming up, on the upperside and the underside of the turnout (the turnout laid normally on a plywood plate but was not included into the layout) ; now I began the same test ... 30 times : again, no noticeable warming up. In normal use, there will be at least 10 s between two succesive flips of a turnout. My PCB is presently equipped with 1800 uF capacitors, and the turnouts flip reliably : I think I will keep this value.
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Post by Deleted on Sept 25, 2018 10:46:47 GMT -5
Some issues : 1) In one turnout the thin wire of the coil broke where it is soldered to the PCB. Overheating or mechanical problem ? Presently, after replacement (I didn't succeed in re-soldering it) I use the combination 9v / 1800uF, it seems that this is enough after a time for "break in" (does it exist with turnouts, too ? ). 2) In another turnout, the neodyme magnets went out of their "receptacles" ; superglue and "thin" sand paper ... and the turnout worked again !
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Post by modelwarships on Mar 18, 2020 13:43:31 GMT -5
What about pulsing on the supply side? Hitting the switch would empty the capacitor and cutout while it recharged long enough for fat finger to get off the switch handle.
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Post by Deleted on Mar 19, 2020 0:46:35 GMT -5
Don't forget that You must pulse with opposite polarities : Your system would need 2PDT momentary switches, like the original Rokuhan system (or two momentary 2 pole pushbuttons) ; and with the Kato system only 1PDT, which can even be "permanent" (like relays in my case) ; the only problem is that in case of "permanent" switches one must "synchronize" the turnouts at power up (switching once back and forth), to reflect the position of the switches, this is done automatically on my layout. And calculate about 1.5 A per turnout, especially if several are switched together ; I use a desktop switching power unit, dedicated to the turnouts.
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Post by modelwarships on Mar 19, 2020 14:13:25 GMT -5
I already have the DPDT momentary switches in place and they work. I'm thinking about just putting a capacitor between the power supply and the switches. That way whichever switch is thrown will get the pulse of power from the capacitor. My concern would be how much delay for recharging would be and would it be sufficient to pause the flow through the DPDT switch if one is slow to release the switch. I don't really want to reinvent the wheel here, just make sure each flip of the switch has the right pulse to fully throw the points. Maybe just adapt a Circuitron Snapper Power Supply?
I suspect the problems I am having with the Rokuhan turnouts is largely a ballast or scenic glue intrusion or friction issue. I have some extra Teflon tape that I may try sealing up the bottom of these turnouts to ensure a friction free surface for the slider handle to move on. After all I don't want have to reach in and fix them every time they fail to throw completely.
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Post by Deleted on Mar 19, 2020 15:27:55 GMT -5
The Kato system is the simplest of them all (why use a complicated system instead of a simple one ? ), and the price for such capacitors is less than 0.6 (€) each (compare with the price for the turnouts ... or Rokuhan's proprietary switches ! ) ; with the values indicated the pulses are about 100 to 150 ms (over a "significant" voltage : the pulses are exponential) and this is enough for a reliable operation. The only add-on that I made is two freewheel diodes (1N4148) on each switch ( = relay). And since there is one capacitor per turnout, the problem of "latency time" is solved : don't forget that flipping turnouts back and forth continuously will cause their destruction via overheating ; the only problem could be the peak current that the supply must deliver if too many turnouts flip simultaneously (into the direction where the capacitors are connected to the "+" ; discharging them does not draw any current ! ). I leave a safe delay of 500 ms between flipping every group of turnouts (btw into any direction), this is perfomed via software. And : any DIY solution is all the way cheaper than Rokuhan's dedicated switches, and can easier be integrated into a control panel !
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Post by modelwarships on Apr 18, 2020 10:32:06 GMT -5
UPDATE: I installed the Circuitron Snapper upstream of my DPDT center off momentary switches and can verify that it works WELL!!! I had one other pair of turnouts that I had earmarked for replacement due to frequent incomplete throwing of the points. I had assumed that I was too careless with the scenic glue and this was hanging them up, but now they throw consistently! In fact all turnouts are operating reliably. I wish I had tried this before replacing some of the others as I used them to test on before risking my newly installed ones and they snap back and forth like new.
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Post by Deleted on Apr 18, 2020 17:18:36 GMT -5
I looked at the specs for Your "Snapper", it seems not to be designed for Rokuhan turnouts, rather for "classic" 2-coil sytems. But if it works, be happy ... For myself I prefer the Kato system, since it needs only an SPDT, i.e. one contact on my relays ... On the right hand side of the picture below, You can see the eight 1800 uF capacitors for the 8 turnouts (the turnouts are operated as 3 groups, one for 4 turnouts and 2 for 2 turnouts each), mounted on a PCB.
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Post by husafreak on Apr 19, 2020 12:32:36 GMT -5
As someone who has bought a few Rokuhan turnout switches I am interested in this discussion. But I don't have complicated layouts with lots of switching. But a bit lost too. alberich's system is DIY and I don't really understand it, or how it all goes together. Meanwhile the Circuitron Snapper sounds great but I got lost investigating it further. Regarding the Snapper, is the idea that you buy them (approx. $35 each) and use one switch to operate each one ($3) then you can operate 5-10 Rokuhan switches AT THE SAME TIME time from each Snapper? And how much voltage is necessary to do that? So far I have only operated my switches singly or in pairs, so there is no cost savings with the Snapper as I have done. Regarding alberich's solution I guess it is made safe for the switch coils through the delay, which is a safety feature for the Snapper too.
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