Transformer isolating a Clearcom feed?

Archived from groups: rec.audio.pro (More info?)

I hate comms. A necessary evil.

I might have to modify some stuff I made some time ago, to work with
clearcom from a slate mic
I want to transformer isolate, ie not connect Their Ground to My (nice
clean) Ground.

A typical Clearcom cct is
http://www.clearcom.com/support/pd [...] _rs501.pdf
but I dont have access to a CC system to check it out at the moment

Will a any old 1:1 transformer, say 600 ohm do. I'll add 47uF non
polar in series, just in case. The sig level on clearcom is only
-10dBish ISTR

thanks


martin

Archived from groups: rec.audio.pro (More info?)

On 16 Sep 2005 20:08:32 -0400, in rec.audio.pro kludge@panix.com
(Scott Dorsey) wrote:

>martin griffith <martingriffith@XXyahoo.co.uk> wrote:
>>I hate comms. A necessary evil.
>>
>>I might have to modify some stuff I made some time ago, to work with
>>clearcom from a slate mic
>>I want to transformer isolate, ie not connect Their Ground to My (nice
>>clean) Ground.
>
>Clearcom is an unbalanced system. There are balanced intercom systems
>from guys like Telex. But each station puts a low-Z unbalanced output
>onto the line, and each station takes a high-Z unbalanced input from
>the line, and there is a 600 ohm termination resistor bridged across
>the line inside the power supply box.
>>
>>Will a any old 1:1 transformer, say 600 ohm do. I'll add 47uF non
>>polar in series, just in case. The sig level on clearcom is only
>>-10dBish ISTR
>
>You probably want a high-Z input transformer. I'd say make a cable
>and feed it into the input of a DI box. The higher your input Z,
>the less you will affect the level on the other stations.
>--scott

Thanks, Scott, another look at the cct and it looks as if it needs
about 400R o/p impedance, so I'll stick a 1K pot in series and adjust
for minimum smoke.



martin