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26th March 2010, 12:54 PM
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#1 |
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diyAudio Member
Join Date: Dec 2006
Location: Durham, UK
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Magic Eye VU Meter
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/201....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 Last edited by seroxatmad; 26th March 2010 at 12:55 PM. Reason: Added link |
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28th March 2010, 04:12 AM
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#4 |
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diyAudio Member
Join Date: Nov 2007
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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.
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28th March 2010, 07:48 AM
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#5 |
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diyAudio Member
Join Date: Feb 2009
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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.
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28th March 2010, 02:00 PM
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#6 |
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diyAudio Member
Join Date: Sep 2003
Location: Alps:Tube amp designs over 150W, SMPS guru.
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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 |
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28th March 2010, 06:22 PM
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#7 |
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diyAudio Member
Join Date: Dec 2006
Location: Durham, UK
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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. Last edited by seroxatmad; 28th March 2010 at 06:47 PM. Reason: added pic |
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Moved to tubes for better visibility.
