Has anyone built the Whitlock bootstrap receiver?

http://www.jensentransformers.com/an/ingenaes.pdf

I know it is a patented circuit, but does that mean we can still build it at home ?
I also know the circuit is employed in the THAT 1200 series.....
but I'd like to give it a try.

I have some INA134's and some OPA2134's to make the basic instrumentation amp, but I have not found any component values for the circuit in his PDF.

Any ideas on values for the extra parts Whitlock adds ??

=FB=

With FET opamps the whole exercise is pointless as you can easily reach an input impedance of 10 MOhm without any bootstrapping.

Samuel

Agree. They make a big deal of that adding noise, but clearly once you have a source connected it dominates (unless it is extremely high-Z).

One of the more valuable details I believe is the way they handle RFI. I actually haven't looked at all the claims yet though.

> a patented circuit, but does that mean we can still build it at home?

US patent law allows building a working model of a patented invention for study.

Obviously you can't put it in production without talking to Whitlock.

Where the line between "study" and "exploitation" is drawn... consult a lawyer.

> I have not found any component values for the circuit in his PDF.

??? Example values for the bootstraps are right below Fig 5 and above Fig 10 in the paper you cited. Oh, C in Fig 5 is not given but obviously it needs to be a few uFd to drive the example 10K resistors.

[quote author="PRR"]
??? Example values for the bootstraps are right below Fig 5 and above Fig 10 in the paper you cited.......[/quote]

OK.
I wasn't sure if those values were just rounded "easy numbers".... for simplified equations. thanks.

=FB=