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VK2ZRG > DESIGN 26.03.06 06:36l 27 Lines 958 Bytes #999 (0) @ WW
BID : 2288_VK2ZRG
Read: GUEST
Subj: Re: Logic gate IC question
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Sent: 060326/0208Z @:VK2WI.#SYD.NSW.AUS.OC #:9882 [SYDNEY] FBB7 $:2288_VK2ZRG
From: VK2ZRG@VK2WI.#SYD.NSW.AUS.OC
To : DESIGN@WW
VK2ZRG/TPK 1.83d Msg #:2288 Date:26-03-06 Time:2:00Z
Neil ZL1ANM wrote in part re Andy's Logic gate IC question :-
>Most op-amps work well in this application but have relatively low input
>impedance (couple of thousand ohms). If you require minimal loading, use
>an FET op-amp, such as the TL-071. They have input impedances of 10 Meg
>or more, and circuit configuration is otherwise identical.
Hello Neil and readers,
I don't know of any op-amps with such a low input resistance. I just
grabbed my National Semiconductor handbook off the shelf and had a look
at the LM741 data. Its input resistance is typically 2 megohms with a
300 kohm minimum. To get a really high input resistance with a LM741 or
any op-amp, you can just connect it as a voltage follower.
73s from Ralph VK2ZRG@VK2WI.#SYD.NSW.AUS.OC
Taglines by Colin Coker G4FCN
C Program run, C Program Crash...ReWrite in Pascal!
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