VU meter teardown - not what I expected

Thread Starter

andrew331

Joined Apr 28, 2015
14
Hi
In a box of parts that I will most likely newer use I have some VU meters, old analogue types that used to be very common in audio equipment.
I decided to have a look inside one.
What I expected to find was:
'The original VU meter is a passive electromechanical device, namely a 200 µA DC d'Arsonval movement ammeter fed from a full wave copper-oxide rectifier mounted within the meter case.'
The meter movement was as expected but no sign of any rectifier!
Could anyone explain this?
Andrew
 

Thread Starter

andrew331

Joined Apr 28, 2015
14
I damaged the meter taking it apart, so the bits are no in the bin!
I am thinking it may have needed some external components? Diode?
 

Nykolas

Joined Aug 27, 2013
115
VU meters on consumer stereo equipment was sexy, but not Vu. These meters are standard mV movements. A rectifier and a RC network (of varying complexity) would simulate the ballistics of a true VU meter. E
 

DickCappels

Joined Aug 21, 2008
6,533
Hi
In a box of parts that I will most likely newer use I have some VU meters, old analogue types that used to be very common in audio equipment.
I decided to have a look inside one.
What I expected to find was:
'The original VU meter is a passive electromechanical device, namely a 200 µA DC d'Arsonval movement ammeter fed from a full wave copper-oxide rectifier mounted within the meter case.'
The meter movement was as expected but no sign of any rectifier!
Could anyone explain this?

Andrew
(Emphasis added by me)


You stated that the movement was fed by a full wave copper oxide rectifier inside the case . I think you answered your question before you asked it.
 

SLK001

Joined Nov 29, 2011
1,548
You stated that the movement was fed by a full wave copper oxide rectifier inside the case . I think you answered your question before you asked it.
He stated that this is what he expected to find. He did not find what he expected, so was wondering how a linear movement was made non-linear.
 

DickCappels

Joined Aug 21, 2008
6,533
Thank you, I misread the original post and understand, he was talking about the prior meter.

In that case I endorse Nykolas's explanation in post #5.
 

Thread Starter

andrew331

Joined Apr 28, 2015
14
Thank you, I misread the original post and understand, he was talking about the prior meter.

In that case I endorse Nykolas's explanation in post #5.
Thank you all.
Nykolas was right, these are not proper VU meters, just regular dc meters that need some external circuitry.
 

alfacliff

Joined Dec 13, 2013
2,458
a lot of VU meters on consumer devices use an external rectifyer and rc filter to simulate the non liinear charistics of a coper oxide rectifyer to give a logarithmic scale. your meter just does not have them inside.
 
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