Meter Buffer Amplifier?

[David Halliday (Volt Computer)]

How about powering it from the unregulated side of your power supply?

You could probably derive +/- 18 from somewhere and build a simple
transistor buffer ( or use a high-voltage opamp )

Other idea would be to pop open the case and shunt the resistor - make the
meter actually a +/- 10 volt and then feed it from a buffer that cuts the
signal by 1/3rd.



-----Original Message-----
From: Grant Richter [mailto:grichter at execpc.com]
Sent: Wednesday, June 23, 1999 11:01 AM
To: Synth-DIY
Subject: Meter Buffer Amplifier?


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?

Any suggestions appreciated.

Grant