Discussion....

**bfish** · January 12th, 2010, 08:37 PM

OT, but another "standards" scam is LEED, by the Green Building Council. A building owner pays a hefty 5-30 percent premium for a LEED AP to document the construction process. He could get exactly the same result by merely telling the architect he wants above-average efficiency, IAQ, and friendlier materials. All the owner gets for those extra $ is a certificate to hang on the wall. The AP gets rich.

I'm all for better efficiency, air quality, etc, but I'm to the point that the word green makes me sick. Behind almost every use of it is some con man padding his offshore account.

Added;
(All except Altec green of course)...

**Nipper** · January 12th, 2010, 10:47 PM

Ok someone please tell me why anyone would want or need to use an amp as a motor control.

I'm missing something here.

**valhallax** · January 12th, 2010, 11:30 PM

saw an altec 260 the other day on the bay, may still be on there..was removed from service powering a vynil cutting lathe, weighed in at 165 lbs!

**Audio_by_Goodwill** · January 13th, 2010, 01:18 AM

Originally Posted by Nipper

Ok someone please tell me why anyone would want or need to use an amp as a motor control.

I'm missing something here.

I'm not sure why it would be used over a VFD, but using one over a switch would be that you can control the speed of the motor.

**Audio_by_Goodwill** · January 13th, 2010, 01:24 AM

Originally Posted by valhallax

saw an altec 260 the other day on the bay, may still be on there..was removed from service powering a vynil cutting lathe, weighed in at 165 lbs!

Even more, the altec literature and the auction claim 186 lbs.

The ebay auction is what prompted my search for info on the amp. I don't know what I'd do with it, but I thought about bidding.

**Nipper** · January 13th, 2010, 10:53 AM

I can buy a variable speed motor controller for a fraction of the cost of that amp!

**Audio_by_Goodwill** · January 13th, 2010, 11:07 AM

Originally Posted by Nipper

I can buy a variable speed motor controller for a fraction of the cost of that amp!

Now yes, maybe not then, and I'm thinking the amp may yield finer adjustment. I think this type of thing was done in testing situations, where precise control was needed.

**Nipper** · January 13th, 2010, 11:07 AM

Maybe Black & Decker will set up their own standard to certify amps that can run their drill motors properly.

They could even create a test tone called "Deep Hole".

**Panomaniac** · January 13th, 2010, 11:19 AM

It was motor controllers that got me interested in Class-D amps back in the late 80s, early 90s.

We used a set of 4 controllers that took 220V AC in, converted it to DC then made 220V AC 3 phase to run the motors. The chopper circuits ran at about 22KHz.

The way the motor speed was controlled was to vary the frequency of the 220V sine wave. The higher the frequency, the faster the motor turned. And because it was always full voltage, it was always full power. Same as for the amp motor controllers mentioned above. The controller could also apply DC to act as a brake. The 3 phase allowed the direction of rotation to be controlled. Using Class-D (switching) just meant they were more efficient than a linear amp or PSU. They worked great. Made by Citroen.

**Audio_by_Goodwill** · January 13th, 2010, 11:28 AM

Originally Posted by Panomaniac

The way the motor speed was controlled was to vary the frequency of the 220V sine wave. The higher the frequency, the faster the motor turned. And because it was always full voltage, it was always full power. Same as for the amp motor controllers mentioned above. The controller could also apply DC to act as a brake. The 3 phase allowed the direction of rotation to be controlled. Using Class-D (switching) just meant they were more efficient than a linear amp or PSU. They worked great. Made by Citroen.

That was what I was would call a VFD (variable frequency drive).