Meter Buffer Amplifier?

[Grant Richter]

Youse guys are genii!

Attached is a GIF of the schematic from EWB.
Low cost, 1 meg input resistance, able to drive a 3K
+/- 15 volt meter to full 15 volts bipolar.

I LIKE it. Thank you.

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> From: Don Tillman <don at till.com>
> To: grichter at execpc.com
> Cc: synth-diy at mailhost.bpa.nl
> Subject: Re: Meter Buffer Amplifier?
> Date: Thursday, June 24, 1999 1:38 AM
> 
>    From: "Grant Richter" <grichter at execpc.com>
>    Date: Wed, 23 Jun 1999 13:01:10 -0500
> 
>    Mouser carries a nice Modu-Tech +/-15 volt center zero meter,
>    Part number 541-MSQ-DVV-15U.
>    Problem is the meter resistance is rated at 100 ohms per volt,
>    for a total resistance of 3K ohm. This is too low for synthesizer
>    applications and the meter should be buffered. A straight TL071 buffer
>    springs to mind, but TL071s don't like to go with 1.5V of the rails.
>    Rail to rail op-amps don't come in 30 volt ranges, and I'd rather not
>    add a separate +/-18 volt supply.
> 
>    So, question, any of you old timers seen a discrete meter buffer
>    design that will go rail to rail in +/- 15 volt systems?
> 
> Drive it differentially, with two opamps, one inverting, one
> noninverting. 
> 
>   -- Don
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