Magic Eye VU Meter

[seroxatmad]

Hope this is the correct area to start this thread...anyway in the January 2010 Elektor magazine it has an article on a PC USB load indicator using a EM84 Magic Eye tube.

http://www.elektor.com/magazines/2010/january/usb-magic-eye.1191254.lynkx

I was after some advise to use this as a base for an audio line level VU meter.

The main advantage is it works off the USB 5V supply so was after keeping this and running it off a 230/5V plug in mains unit.

Cheers

John

 

[Pano]

Moved to tubes for better visibility.

 

[Eli Duttman]

Maybe a data sheet will help. Look here.

 

[rotaspec]

No mention of where the tube is powered from, but it's gotta be one heck of a step up power supply to get 250v from 5v. Never mind the 6.3v heater. I don't know what the min plate voltage is for these, but I've always seen them running more than 200v. I had one of those tubes but the phosphor was completely gone. There is a Russian version available.

 

[Arnulf]

It is 250V, but at relatively low current. USB can source up to 500 mA to a registered device so consumption should within standard specifications.

 

[richwalters]

Here's a circuit dug out from my old Radiogram. Note; the EM87 display circuit registers peak values as per RF modulation /tuning, and to show rms, the circuit needs modification for audio VU meter apps.

richy

 

[seroxatmad]

Hi

Thanks fro the replies...

The 6.3v heater and the 250v is supplied from a self wound pcb mounted transformer via the USB supply but would like to ditch the USB part and run off a 5 or 12V mains plug in unit, and line level source.

Note pin 1 and 9 is not used in this configuration.

Cheers

John

P.S I am after getting a circuit working to make onto PCB to make as a group buy in the future.