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In Reply to: RE: AD1955 and transformer I/V stage posted by SunRa on June 9, 2007 at 11:19:03:
Hi Florin,
I thought that you wanted to use the 6H30 because you had some on hand. The 6H30 will do a fine job in the circuit. If you are open to alternatives, you might consider 6N1P, 6N23P and 6N6P. They all will drive the Amity in a circuit like the RA Active Output. I have used all four over the last couple of years and my current favorite is the 6N6P.
I need to be more specific of the impedance with the LL9206. The I/V impedance with a transformer after the current output DAC is not just the primary resistance of the transformer, but rather the primary resistance of the transformer plus the reflected impedance of the sum of the secondary resistance of the transformer and the secondary load resistance. There is no free lunch here, meaning that there is still an I/V resistor, but one that consists of parts here and there.
Since the DAC has a current output, think of the transformer as a current transformer with the current from the DAC reflected to the secondary of the transformer, divided by the turns ratio, in the case of the LL9206, 10. There will be an I/V resistor across the secondary of the transformer that will perform the current to voltage conversion. The size of the resistor is determined by the desired voltage. Then this resistance is reflected back to the primary as described above. There is a limitation to the size of the resistor determined by the drive capability of the DAC and losses in the transformer.
There are four primary windings on the LL9206. Parallel the 1-4 winding with the 6-7 winding and parallel the 5-8 winding with the 2-3 winding. Observe proper polarity of the windings.
Dave
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Follow Ups
- RE: AD1955 and transformer I/V stage - Dave Davenport 15:27:15 06/09/07 (3)
- RE: AD1955 and transformer I/V stage - SunRa 05:04:47 06/10/07 (2)
- RE: AD1955 and transformer I/V stage - Dave Davenport 12:50:59 06/10/07 (0)
- RE: AD1955 and transformer I/V stage - SunRa 05:11:44 06/10/07 (0)