Hi Peter,
Am 28.05.2012 17:42, schrieb pws:
Hi,
After all those meta-discussions here's a more serious problem:
I'm playing around with a new e-field probe based on the INA111.
http://www.ti.com/product/ina111
Schematic: http://www.df3lp.de/misc/rx/INA111_preamp.png
Interesting. But where do you get the special parts from?
What is the lower cut-off frequency?
It's working fine and the local interferences are lower compared to
my old non-balanced design running here on balcony. That was the goal.
Amplification is quite enough to drive a M-Audio audiophile 192
soundcard.
There's a second transformer (1:4) at the af-inputs. The coupling
capacitance of those transformers are below 10pF each.
I'm using the shields of a thin double coaxial line for bringing up
the supply voltage. The voltage splitter is located at the far end
inside the small amplifier box.
The problem is that I'm observing to a lot of interferences/microphonics
"from behind" when touching the battery located inside the house.
???
Changing capacity between you and the electrode (s)? Why do you touch
the battery? :-) Any problems when it is in normal use?
73, Stefan
Peter, df3lp
| 
