Convert surplus 50uA meter to 'cosmetic' VU meter?

[lang_dave]

Hi - here's another question about putting some 'cosmetic' meters on a home built mic pre kit.

I'm interested mostly in what type of meter I can get away with using. I know that I'll need to build a buffer circuit depending on what type of meter I use, but to get started I need to know what kind can be used and what kind can't.

For example - there are lots of really cool looking old meters on eBay, but the one's that are actually 'vu' meters, cost lots. Other meters are cheaper, and look just as good.

If I understood what I read so far correctly, a 50uA meter should be serviceable for this.

There are a lot of them for sale here:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=9717357658&ssPageName=STRK:MEWA:IT

Will one of these work?

I recognize that I would have to learn / ask about what circuit to build to drive it, but for now I'm just trying to figure out where to start.

Thanks for your help and patience,

dave

 

[lang_dave]

Further to this - I found the following quote from PRR in one of the earlier threads:

"The 100uA meters would also make fake audio VU meters. Add a big bridge rectifier and a few K of resistance. You will have to fiddle to get the right sensitivity, and the ballistics would be wacky, but fine for line-up tone, overload hinting, and general decoration."

This is exactly what I'm wondering about the 50uA meters. Would the above hold true for 50uA meters? I'm guessing it would, but would love for someone who knows to say 'yes they'll work - go do some more reading...'

Thanks folks,
dave

PS - the thread quoted above is here:
http://www.groupdiy.com/index.php?topic=12598&highlight=meter

 

[gyraf]

yes, you could easily use 50uA meters for this as well.

Those meters look like slow dc-reading meters, so your ballistics will probably be very slow for a vu-meter

But if beautifull movement and not any precision is your priority, these will probably work fine.

Jakob E.

 

[Larrchild]

Since it's usually bad form to connect a VU meter directly across the audio signal due to distorition introduced, someone should cook up a meter buffer board with onboard rectifier and ballistics network to utilise a milliamp meter for audio, yet, switch back to a current meter for limiter GR applications.

Perhaps I'll mess with that.=)

 

[clintrubber]

[quote author="Larrchild"]Since it's usually bad form to connect a VU meter directly across the audio signal due to distorition introduced, someone should cook up a meter buffer board with onboard rectifier and ballistics network to utilise a milliamp meter for audio, yet, switch back to a current meter for limiter GR applications.

Perhaps I'll mess with that.=)[/quote]

ESP's circuit looks like a nice starting point for that:
http://sound.westhost.com/project55.htm

 

[Larrchild]

Thats about right, Clint. You could insert a 2 pole switch at the meter and insert it into the GR metering leg, or have input/output metering.
good.

The front end could be a superbal or inst amp for balanced use. =)