voltage of dimmer output not reading same on two different DVM's

The voltage, though, for an LED lighting system is NOT proportional to current; it's the current average that makes the light output bright or dim. Neither average DC nor RMS are suitable measures unless it's on a CURRENT scale rather than voltage.

whit3rd wrote: ================

** As previously posted *here* by me - the *power* delivered by a DC source is: I average x DC voltage.

A moving coil DC meter or regular DMM will show you both.

Do the math any way you like.

...... Phil

d in the AC portion.

** Not true.

The reason for needing a true RMS value is to predict heating in a resistan ce or maybe a fuse . So you cannot omit the DC component.

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I'll bite. 99% of what I did using an AC meter was measuring power supply ripple and abcense/presence of house AC or 24 VAC systems.

When I designed an I-V converter so we could measure the outut of a UV arc lamp source, that had to be TRMS.

We had lots of phase angle fired AC controllers (before I was hired) operat ing into variacs to drive 40V tantalum heaters (200-300W). They either wor ked, had a short inside the vacuum system or blew the semiconductor fuse. I then made sure they SCR;s were 25A, added the current limit option and an extra 3AG fuse. Life got better.

New or upgraded systems went with 1200W DC power supplies. 30V 40A or so. We would have liked a power meter and a programmable temperature controlle r. The other controllers were obsolete. They had no temperature display and had a proprietary dual SCR unit. Newer replacements would use standar d process signals like 4-20 mA 0-5, or 0-10V That allowed us to reduce panel size and not have a "stupid panel" that rea d ersatz AC voltage and ersatz AC current and had a temperature display. A t one point in the earlier system, Power was important. A three-phase powe r meter was adapted to do the power of two low voltage single phase heaters at the cost of about $1000.00 USD. There were 7 heaters in a typical sys tem. Sometimes wired wierdly.

In a custom system (prior to the IBM PC) that I was involved in, we did it the right way. The heaters could be controlled by voltage, current, tem perature or power. The uncontrolled variable became a limit. I implemente d an energy calculator and stability creiteria and recipies. The energy ca lculator could detect a shorted thermocouple onheat up or a misplaced on, The spreadsheet programs were not invented yet.

Ron D. wrote: ===========

** Don't bite off more than you can chew.

** Totally irrelevant to the issue.

** Got SFA to do with needing true RMS values.

IF you need the true RMS value, the DC component must not be omitted.

..... Phil