Do "typical" taut band D'Arsonval meter movements pass the moving coil current through the suspension bands?
Its been so many years since I worked on a meter movement that the only ones I'm familiar with are pivoted suspensions with coil currents passed through the two restoring harirsprings.
Thanks guys,
Jeff
Yes, at least the ones designed for low currents, which is where the design really shines, having virtually zero friction and tiny amounts of torsion. An unfortunate side effect, if alignment isn't just so, zero drifts with temperature.
WOW! And i thought that 5uA F.S. was the best movement in a production environment.
"Jeff Wisnia"
** IME - yes.I owned a lovely analogue multimeter by Sanwa that used a 2uA FSD (
500kohms /volt) taut band movement......... Phil
Nice meter. Must be a bit schloooowwww to be that sensitive, though, I would think--you need a bit of torque to get a fast movement.
Cheers,
Phil Hobbs
"Ol' Duffer"
** Can't recall if temp affected my old Sanwa 501 ( 2uA FSD ) meter like that.But one did have to re-zero it for vertical or horizontal operation.
......... Phil
** See the nice, sharp pics of the Sanwa N-501 here - if in any doubt:
............. Phil
You're going to have to select the Rce, Cce or the IGBTs, and thoroughly study the operating range of the power elements. It is far more involved than simply plugging values into their app circuit and reading "typical" graphs. If the damned drive is that expensive then go to a GMR and actually quantify the current with complete isolation and more than sufficient accuracy and bandwidth.
......... Phil
"Reg Edwards"
** Must have been entertaining.Ever tried the measure the ohmage of a loudspeaker system with a DMM while a disco is running full tilt in the same room ??
......... Phil
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