Excerpted from an email from Terry Walker, commenting on the merits of the ES201 design. (8-30-8)


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I got a better picture of the ES201 op amp from a different site and attached it to this email.  The amplifier is similar to the one in the EC-1 analog computer, except for using three tubes instead of 1.  The design is not very good, as changing the input offset adjustment will cause the positive feedback value to also change and alter the effective gain and error curve.

 I include this because I thought that you might find it interesting to make a copy of this amplifier and compare its performance to the K2-W or the others you have worked with.

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