| Modifying the TW523 Power Line
Interface
These instructions are based on Hans Attersjö's
Home page. I have not attempted this modification and I accept no
responsibility for the effects of anyone making these modifications.
You follow these instructions at your own risk.
This one is quite tricky to modify due to the limited space inside the
module. This module has no silk screen printing of component numbers so I
presume that you know the colour codes of resistors. If you don't, you
wouldn't be reading this or would you :-)
- Open the module by removing the screw between the legs of the
incoming power.
- Change C14 (2E225) from 2.2uF 250V to 1uf 400V. Fix this one with
silicon or epoxy glue.
- Change C10 (2E224) from 0.22uF 250V to 0.1uF 400V.
- Change R25 from 22 Ohm 0.5W to 47 Ohm 1W.
- Change R12 from 100k 0.5W to 220k 0.5W.
- Change the VDR from 130V MOV to a MOV of 250V RMS. 230V and 240V
users should use a 275V MOV.
It was impossible for me to find a 1uF/400V so I used two 0.47uF/400V
in parallel, one soldered in the original position of C14 and the other
one on the back of the board. Both were fixed with some silicon. This
means that it was impossible to close the box so I made a couple of
plastic strips about 1/4" (6mm) wide to use as spacers between the
two parts of the box. I finally fixed the whole assembly together with
some good quality scotch and glued an adapter for my plug standard on the
standard incoming connector. One should perhaps glue the plastic strips to
one of the halves of the box but I was in a hurry and didn't.
Even if you could do a nice mechanical assembly, don't even think about
passing some electrical approvals. It would almost certainly fail! BTW, we
don't have those things where I live. First, the opto coupler does not
have sufficient insulation rating. Secondly, the legs of the opto
coupler's in and out side, are too close on the printed circuit board.
Third, the material of the printed circuit board is not good enough, etc.,
etc.
However, I consider it fairly safe in a dry and child free environment.
My TW523 is BTW, mounted inside a locked cabinet. Even if you don't use a
modified TW523 but especially if you do so, I would suggest that you
verify that your computer has a good ground and that you use differential
circuit breaker (GFB or GFI depending on where you are) on your incoming
power. A short circuit between input and output side of the TW523 could
otherwise cause your computer to become a death trap!
While the module is already open, also change the 68V 1W zener diode to
a 3W type. You could perhaps also use two 33V, 3W zeners in series. This
diode fails often, even on 110V.
Update. This unit can be now be bought in 220V version from Home
Automation Systems for $59.95. However, it is still cheaper and more
adventurous to modify a 110V version yourself!
If you attempt these modifications, please let me
know your results, and read the warning on the X-10
240 volt modifications page. |
Redoak
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