[sdiy] meter meter on the wall

[J. Larry Hendry]

I have thought of this myself too.  I have not tried anything yet, but I was
leaning toward using one of those op amp circuits designed to return
absolute value.  Then a bipolar LED and one switch.  The switch would be for
AC / DC.  The meter could display the absolute value of DC with the LED
indicating polarity.  For AC, it would seem to me that the meter would
display some DC value representing an AC average.  I thought the switch
could be used to control the gain in the buffer so the meter scale would
actually display a number representing peak-to-peak for AC.  I expect to
have to play with that value as different types of AC will give different
average values.  But, this is for general indication rather than
calibration, so I thought I could select a gain value that was close enough.
My $.02
Larry Hendry


----- Original Message -----
From: steven_thomas <steven_thomas at ntlworld.com>
To: BRADSHAW <E.K.Bradshaw at newcastle.ac.uk>; <>
Sent: Thursday, February 22, 2001 8:33 AM
Subject: Re: [sdiy] meter meter on the wall


Hi Ed,
         well I too have a meter in my modular setup that I haven't wired up
yet. I have the synthi A/VCS3
service manual and looking at the meter schematics..it does basically what
you suggest..a rectifier setup for the  signal voltages,  a DC follower for
control voltages (assuming they are all positive in your setup)
some resistors to adjust for whatever F.S.D. is on your meter. Plus a switch
for monitoring either signal
or control voltages on the meter. In the synthi a couple of transistors are
used ..but I guess modern op-amps will be best for the buffering.
Hope this helps.
cheers steve thomas
----- Original Message -----

From: BRADSHAW <E.K.Bradshaw at newcastle.ac.uk>
To: <synth-diy at node12b53.a2000.nl>
Sent: Tuesday, February 20, 2001 10:03 PM
Subject: [sdiy] meter meter on the wall


> I don't suppose any one can help me out.
>
> I want to put a synthi A style meter on an output module - my
> question is - what sort of thing do I deep to control it?  my own
> minimal-tech guess would be: Buffer - rectifier - voltage
> divider/trimmer - galvonmeter.  Is any of this remotely right?
>
> thanks for any help.
>
> Eddd
>
> E.k.bradshaw at ncl.ac.uk
>