Re: CM11A hangup: Any better products?

[nobody@xxxxxxxxxxxx (Dave Houston)]

John Galvin reverse engineered a partial CM11A schematic. It's at...

     http://home.pacbell.net/lgalvin/CM11AX-10a.gif

It includes the oscillator.

I think if you look at your RR501 you'll find it uses one winding of the
same model transformer as is used for the input as the L with a couple of
27pF caps. They use so many of the transformers, they probably only cost a
few cents. They assemble them in mainland China where production costs are
nearly nil. After all, they tune the wireless devices by bending the single
wire loop used in its oscillator.

Joerg <notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote:

>Hello Dave,
>
>> It is ABSOLUTELY so! All of the X-10 made PLC transmitters for which I've
>> seen schematics (and looked at their innards) with the exception of the most
>> recent RR501 (last 7-8 years?) use an LC controlled transistor oscillator.
>> You can see the circuit in the schematics for the TW523, CM11A, CM15A,
>> TM751, mini & maxi controllers. etc. If you need URLs, I can supply them.
>
>Yes, do you have the URL for your version of the CM11A?
>
>> PLC transmitters made by SmartHome and other manufacturers may use
>> resonators and generate the PLC carrier with a PIC - I haven't seen many
>> schematics for them.
>>
>> The most recent RR501 does generate the 120kHz with the PIC _BUT_ the PIC
>> itself uses an LC circuit instead of a crystal or resonator on its OSC pins
>> so it's unlikely to be any more tightly controlled than the others.
>
>IIRC mine has a fixed resonator. A tunable LC would be more expensive in
>production.
>
>> The same is true for all of the wireless devices.
>
>I know. Those are a pain, hardly adjustable. I found some of the key
>chain ones all over the map so we quit using them.
>
>Regards, Joerg
>
>http://www.analogconsultants.com