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Author Topic: How to increase the current capacity of an XM17A or similar addressable PS?  (Read 6282 times)

HA Man

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I need the functionality of an XM17A or similar X10-addressable DC power adapter (such as XM13A, XM16A, etc.), but need more current capacity.  (I would like to control surveillance cameras having IR illuminators, which can draw up to 500mA @ 12vdc).

Those XM addressable DC power adapters have a number of possible applications, so it's a shame that they have been discontinued.  :(

Anyway, does anyone have any idea whether there is any practical way to produce higher currents, with the full X10 control functionality of the XM device, including the mutually-exclusive action within four-unit-code groups?  If so, how?

I considered trying to rig up some sort of relay on the output of a conventional high-current DC power adapter, with the relay being controlled by an XM power adapter, but that turned out to be problematic operationally - not to mention being surprisingly expensive, and taking up twice the number of AC receptacles.
 
I also considered using an Appliance Module controlling a conventional DC power adapter that has the required current output - unfortunately, the "mutual-exclusivity" of units in the four-unit-code "group" is not provided by the Appliance Modules.

So, I even wondered if an Appliance Module could be modified so that it could be controlled by an XM module (rather than directly by the X10 signal), in order to plug in a higher-capacity DC adapter, while retaining the XM's full X10 control functionality.  But, that gets to be quite kludgey - not to mention using twice as many AC outlets!

So, at this point, I'm stumped and fishing for any practical ideas...

Thanks in advance!
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Brian H

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The Appliance Module modification could be a safety issue.
They have a power line derived power supply and the AC Line maybe the common DC buss. Any external wiring could be 120 volts above safety ground.

Maybe a small DC controlled solid state switching module could be used to control the higher current DC you need. From the X10 switched output of the XM17A or any of the other X10 camera power supply models. As the solid state switching modules don't take a great amount of control current.

If I see anything of interest more information can be added.

If you decide on a relay. It maybe advisable to have a back biased diode across the relay coil. So when you turn it off. There is not a inductive spike on the controlled voltage connection.
« Last Edit: June 14, 2016, 07:02:00 AM by Brian H »
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Brian H

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I found this on the All Electronics web site.
http://www.allelectronics.com/make-a-store/item/srly-2402/1.5-amp-solid-state-relay/1.html

It can be controlled by the switched 12 volts from a XM17A to switch  AC power to a higher power wall wart.
It is rated for 240 VAC but I did not see a minimum AC voltage needed to switch On and Off. So 120 volts AC should also be OK.
Control voltage 9 to 16 volts DC with a maximum DC control current of 16mA.

Would require you to do some custom assembly and wiring.
Others may have an easier or smoother method.

I don't know if a resistor or zener diode could be used to drop the switched 12 volts from the XM17A to the 3-10 volts DC needed to control this Crydom module. It can switch a DC voltage directly On and Off.
http://www.allelectronics.com/make-a-store/item/srly-63/3a-solid-state-relay-for-dc-loads/1.html
« Last Edit: June 14, 2016, 07:35:38 AM by Brian H »
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HA Man

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Actually, my first thought had been to use a solid state relay on the output of a 500mA DC supply, controlled by the output of the XM module.  But, I kind of shied away from that for a couple of reasons:
  • All of the SSRs that I found at the time were quite expensive (much more than the 1.5A device that you found)
  • It looked like the arrangement would require a lot of special design work - that's a bit beyond my knowledge level
  • The "packaging" of the add-on components looked like it would be difficult and rather costly

That led me to look for alternatives - such as using the Appliance Modules (to switch conventional DC adapters) in place of the XM power modules.  That should work, and would be relatively straight-forward to implement, but wouldn't turn off the other multiplexed camera(s) when another gets switched on...

I wonder if there is some way to emulate the XM's mutually-exclusive operation using Appliance Modules.  Probably could be done with AHP, but probably would need to "commandeer" the monitored House Code in order to track which camera is on.  <Sigh!  ::)>

A different approach would be to use the XM outputs to switch only the video signals from the cameras - but I'm not really sure what sort of switching device would be suitable for multiplexing the video signals... and one big disadvantage with this scheme would be that all power supplies would remain on all the time, wasting energy.

I dunno... it's seeming like there is some kind of significant gotcha no matter how I approach this.  :-\
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Brian H

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I am not an AHP expert but it maybe able to emulate the mutually-exclusive action. Using Appliance Modules.
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bkenobi

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Although it would be nice to have DC adapters that were directly X10 addressable, I don't personally think modifying one that is speced to low would be the best solution.  I'm not an EE, but it seems to me that it would be easier/safer to just use an appliance module with a relay (as Brian suggested) rather than taking a chance at violating the ratings and having insurance deny your claim for the house you burned down.   :o
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HA Man

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I am not an AHP expert but it maybe able to emulate the mutually-exclusive action. Using Appliance Modules.

I know of one way to do it in AHP, but it takes a bit of "programming" to do it, and ties-up the monitored house code "bank"... Of course, if one used multiple interfaces, with one dedicated to the camera control function, then tying-up a monitored house code in the dedicated interface wouldn't necessarily be a problem, overall.

I think the biggest disadvantage might be the timing and conflict issues, due to needing multiple X10 operations from AHP to accomplish the proper switching sequence, as opposed to the hardware-based equivalent action done by the XM adapters themselves - which I believe occurs with only one X10 transmission (not sure).  AHP control also probably would slow down the switch-over somewhat, but a bigger worry might be potential malfunction due to X10 collisions from the multiple controllers (assuming that the camera control interface is in use concurrently in a system with other X10 controllers).  I guess the worst case would be if a camera "off" command got trounced, then the subsequent "on" command for another camera would turn on the second camera while the first one was still on, scrambling the video signal.  And with my luck, that would happen right when something critical needed to be captured on the video!  :-[
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HA Man

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Although it would be nice to have DC adapters that were directly X10 addressable, I don't personally think modifying one that is speced to low would be the best solution.  I'm not an EE, but it seems to me that it would be easier/safer to just use an appliance module with a relay (as Brian suggested) rather than taking a chance at violating the ratings and having insurance deny your claim for the house you burned down.   :o

Well, if we bring potential insurance quibbles into the equation, then we probably would need to avoid a lot of things beyond X10 devices, modified or otherwise...  ::)

But yes, intentionally overloading a device sure is a good way to get into trouble.  I didn't intend to imply doing that.  The requirements of this application demand ~12vdc power capable of delivering several hundred milliAmps, but the highest current rating that I'm aware of for an XM adapter is 200mA, with most XM models rated for only 80mA.  The XMs are also unregulated, so the voltage varies from upwards of 25-30vdc (no load) to about 10-12vdc at their full rated current load, making them a less-than-ideal source of a DC control signal for any devices that are "finicky" about their applied DC voltage - like some relay coils.

I believe that Brian's suggestion was to use an SSR (or relay, implied) on the output of an adequate-capacity conventional DC power adapter, with the XM module's output used as the on/off control signal to that SSR or relay.  That scheme would not involve an Appliance Module at all, and also would need no modifications to the power adapters themselves.  That is a reasonable approach, IMO, but does require custom add-on circuitry, that involves some circuit design and physical construction and packaging of the relay circuitry.  (Even that could give an insurance company some "quibble room"... ::))

As you say, it really is unfortunate that no XM adapters have adequate rated current capacity... and it's also very unfortunate that X10-addressable DC power adapters are not currently in production.  That functionality would be handy for many applications.

The fact that the XM devices (or some equivalent) are not in production also makes it somewhat questionable to design any "system" that relies on them - due to the eventual inability to get replacements, if needed.  That's one reason why I'm fishing for ideas that accomplish the XM functionality using some other (in-production) devices... and one reason why cobbing-up custom circuits also is somewhat risky in terms of maintenance.

Bottom line, it's why I'm sort of "holding out" for a more "off-the-shelf" solution for this application, rather than just diving into some custom add-on circuit or other modification.
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bkenobi

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I was just saying messing with the internals of the power supply could be bad if that puts A/C to the outside of the enclosure unintentionally.  I have modified several of my X10 and non X10 devices, but I am wary of modifying the PSU beyond replacing components 1-for-1.  If I were an EE and knew what the components were for, then I'd feel more confident in making such changes.  The insurance bit was really just saying that since I don't know the potential issues I may cause, I don't want to have to try to justify causing a fire hazard with the argument "cause the internets..."  :'
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HA Man

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I was just saying messing with the internals of the power supply could be bad if that puts A/C to the outside of the enclosure unintentionally.  I have modified several of my X10 and non X10 devices, but I am wary of modifying the PSU beyond replacing components 1-for-1.  If I were an EE and knew what the components were for, then I'd feel more confident in making such changes.  The insurance bit was really just saying that since I don't know the potential issues I may cause, I don't want to have to try to justify causing a fire hazard with the argument "cause the internets..."  :'

Doing things that expose people or equipment to hazardous voltages certainly is neither wise nor desirable.  I don't believe that any of the ideas here - other than the one to control a "neutered" Appliance Module via an XM Power Adapter - involved any sort of modification to the innards of any of the power adapters or modules (which is a big plus, from my perspective).

Being unfamiliar with the circuitry of the Appliance Modules, I was surprised to learn that their circuit common is tied to the hot side of the AC line.  In that case, if it was desired to "inject" the DC power output from the XM module into the Appliance Module as an on/off control signal, then probably an opto-isolator would be needed - to protect the XM module... and the user.  Actually, the use of an opto-isolator would have the additional benefit of eliminating the issues caused by the unregulated nature of the XM adapter's output.  Hmmm...
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HA Man

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Just on the chance that some sort of modification of a AM466 or AM486 Appliance Module may be called for, does anyone know where to find a reliable circuit schematic for the current-issue of those Appliance Modules?  In particular, are there any specs for the relay coil and/or the relay control circuit's input to tell what sort of signal would be needed for either of those?

TIA!
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Brian H

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I have not seen an updated schematic for the CFL Friendly, Appliance Module with the Sonix surface mounted controller chip.
I know the power supply is now around 4.2 volts DC not the older models that are around 15-18 volts DC.
I did a partial schematic of just the power supply and ratchet switch coil activation circuits.
When an X10 On or Off power line command is received. The controller checks the output status sensing circuit to see if it is presently on or off. As it uses an alternating  ratchet switch. If it is in the state already the command is ignored. If it has to be toggled on or off . It fires a MCR100-8 for a fairly high half wave pulse through the ratchet switches coil 56 ohm coil. From Line to Neutral. There is a 07D221K TNR across the coil for some inductive spike control.
If you disable the output status sensor. It will fire like a machine gun a few times. Trying to change state.  ::)

« Last Edit: June 14, 2016, 08:32:27 PM by Brian H »
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