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Old 1st Dec 2019, 6:24 pm   #65
'LIVEWIRE?''s Avatar
Join Date: Mar 2006
Location: N.W. Oxfordshire(Chipping Norton)
Posts: 7,307
Default Re: Nostalgia? Probably.

For the benefit of newcomers to both the hobby and this forum, it might be worth (re)stating that an AVO model 7, which was the standard multimeter many years ago had an impedance of 1000 ohms per volt on it's DC ranges. Some inexpensive analog meters today, I believe, are only 1 or 2kohms per volt. The AVO 8 is 20kohms per volt on DC, which places 20 times less loading to a circuit than the 7, meaning that the voltage read will, in most cases, be higher, than with a 7. Valve Voltmeters and DMMs of course have a much higher impedance, typically 10 Megohms, so DC voltage readings taken with this type of instrument will be considerably higher than with any analogue voltmeter. Those of us who have worked with electronics for years are of course aware of these differences, but newbies probably aren't, so I thought it worthwhile to point this out.
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