X10 RF on a cable TV run?

[frank]

Thank you for the schematic.

Interesting...  What if you removed the two connections between the AC line and T2 and connected the coax to T2?  Maybe you go ahead and ground one side of that winding.  And use the .22 uf cap for isolation on the other side.  Maybe not have to worry about an LC circuit on that end?  

On the panel end, would you really need to use anything but another cap?  Wouldn't it seem that if the signal circuit of the cm15a just connects to the AC line, that you wouldn't have to worry about a tuned circuit?  Perhaps it would give you a little better signal though.

I'm not sure if doing this would have an effect upon the tuning of tc1.  Maybe that isn't a tuned circuit.

[Brian H]

CM19A?
It is a USB interface. Doesn't get near any AC power connections and uses RF to a transceiver.

FCC Database has the CM15A in it. Including the schamatic you have {with the added decoupling caps X10 did not include on the board} and the RF Daughter boards.
Along with other things like a Parts List. TC1 is a tunable coil.

http://transition.fcc.gov/oet/ea/fccid/
Grantee B4S
Product CM15A
In the details Tab.

[frank]

CM19A?
It is a USB interface. Doesn't get near any AC power connections and uses RF to a transceiver.

I apologize for the confusion.  I meant cm15a.  I edited my post to reflect that.

Thanks for the link Brian.  So we'll have to be careful with TC1 to ensure its tuning is not altered. 

[dhouston]

Interesting...  What if you removed the two connections between the AC line and T2 and connected the coax to T2?  Maybe you go ahead and ground one side of that winding.  And use the .22 uf cap for isolation on the other side.  Maybe not have to worry about an LC circuit on that end?  

T2 is needed to receive from the powerline as well as isolate the CM15A circuitry. A 1:1 isolation transformer (e.g. Murata 78250) at the insertion point keeps the coax isolated from the mains. TC1 is already isolated by T2 and other components.

Also, my suggestion eliminates any phase issues as the CM15A no longer sends PLC locally.

Using only a cap for coupling risks electrocution if the cap shorts.

EDIT: By using a 1:1:1 transformer, you could couple to both Line1 & Line 2.

• www.mouser.com/catalog/catalogUSD/645/​2130.pdf

[frank]

All good information dhouston!

I'll pursue it.

Thank you.

Frank

[dhouston]

Another point - the purpose of the 0.22µF cap (C7) is to attenuate 60Hz while passing 120kHz. Jeff might be able to model this for the best cap/transformer combination.

[dhouston]

Another point - the purpose of the 0.22µF cap (C7) is to attenuate 60Hz while passing 120kHz. Jeff might be able to model this for the best cap/transformer combination.

In a similar application, NXP uses 47nF and 47µH in series with the 78250 transformer winding. See p40 of...

• http://ics.nxp.com/support/documents/interface/pdf/​an10903.pdf

With a 1:1:1 transformer you can send to and receive from both phases.

Use X2 rated caps - they are designed to fail open.

[frank]

Thank you dhouston.

Good points and the circuit is a nice find.  I had forgotten what 'x2' meant.  But this is a very good use of it.  And the use of a 1:1:1 transformer is ideal.

It has become painfully apparent that I need a way to measure the results to determine the advantage of this effort.  I should take primary readings prior to making the change.

JeffVolp, per your suggestion of using a repeater; does the repeater increase the signal on both legs?

Frank

[JeffVolp]

JeffVolp, per your suggestion of using a repeater; does the repeater increase the signal on both legs?

Any repeater located at the distribution panel will increase the signal on both legs (assuming it is connected to both legs).  The XTB-IIR will increase signal levels well beyond those produced by other X10 repeaters.

Jeff

[frank]

Any repeater located at the distribution panel will increase the signal on both legs (assuming it is connected to both legs).  The XTB-IIR will increase signal levels well beyond those produced by other X10 repeaters.  Jeff

Does the repeater accept input from either leg and then repeat a delayed message to avoid clashes with the original?

[JeffVolp]

Any repeater located at the distribution panel will increase the signal on both legs (assuming it is connected to both legs).  The XTB-IIR will increase signal levels well beyond those produced by other X10 repeaters.  Jeff

Does the repeater accept input from either leg and then repeat a delayed message to avoid clashes with the original?

No, all repeaters that I am familiar with receive the first half of the X10 doublet from either leg, and then retransmit that in bit-sync with the second half onto both legs.  Delaying and retransmitting after the command is asking for trouble.

Jeff

[Brian H]

I would think delaying the transmission would mess up badly with the old dim method. Of turn Lamp Module fully On the send a stream of Dims to lower the level.

[JeffVolp]

I would think delaying the transmission would mess up badly with the old dim method. Of turn Lamp Module fully On the send a stream of Dims to lower the level.

Yes.  And many of us send sequences of X10 commands.  Delaying and retransmitting a command has the potential for colliding with another command being sent shortly after the first one.  Even with collision detection, it is likely that both commands would be corrupted.

Jeff