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Author Topic: Fluorescent lights causing hum bars on VGA line  (Read 3257 times)

Stephen Swaffer

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Re: Fluorescent lights causing hum bars on VGA line
« Reply #20 on: October 17, 2016, 11:22:23 pm »

Amazingly, many people are simply terrible at following a schematic. This is especially troublesome if they happen to be in the maintenance department. I'm teaching a basic audio electronics class to College juniors this semester, and even getting them to understand how to wire the most simple circuit imaginable is tricky. Yes, a battery, momentary contact switch and a light bulb. And they can get that wrong on a desktop electronic playground.

Keep in mind that you had a very unfair advantage over the generation you are teaching.  You used to be able to tear electronics apart and figure out how they worked-and you didn't have media sufficient to occupy 48 hours of each day.  Maybe an hour of TV a couple nights a week-in bad weather?  Otherwise find something to satisfy your curiosity.

My dad was an educator-recently he commented that a lot of students have trouble translating the classroom to real life.  I suspect the same is try of a schematic to real live wires-or a desktop playground to real live wires.  I have a couple of young maintenance techs that are eager to learn-my training this week consisted of explaining a schematic to one of them, then sending him out to a machine and having him marry an old control panel to a new machine.  Give me a year or two and I'll put him up against your college degreed engineers any day of the week ;).
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Steve Swaffer

David Buckley

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Re: Fluorescent lights causing hum bars on VGA line
« Reply #21 on: October 18, 2016, 01:50:47 am »

No wonder people have trouble figuring out 3-way switches. That's probably the most confusing electrical thing most people will ever come across.

Even more confusing on an international forum; a "three way switch" in the USA is what the rest of the world calls a "two way switch"...
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Jonathan Johnson

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Re: Fluorescent lights causing hum bars on VGA line
« Reply #22 on: October 18, 2016, 03:24:26 pm »

Even more confusing on an international forum; a "three way switch" in the USA is what the rest of the world calls a "two way switch"...

Really, it's a single pole, double-throw switch (SPDT). But what is the universal term for a 4-way switch?
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Stop confusing the issue with facts and logic!

Bill McKelvey

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Re: Fluorescent lights causing hum bars on VGA line
« Reply #23 on: October 18, 2016, 05:31:19 pm »

But what is the universal term for a 4-way switch?

Rotary?
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Jean-Pierre Coetzee

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Re: Fluorescent lights causing hum bars on VGA line
« Reply #24 on: September 01, 2017, 03:05:19 am »

Literally dug up from a year ago but thanks for the reply. I simply worked around the problem by changing the projectors refresh rate to 50Hz(same as the mains cycle) and it's minimized to the point where nobody complains.

Management has issues believing techs when a qualified electrician says its fine, won't say anything about other code violations that apparently also gets signed off on...

Country is South Africa BTW...
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Audio Technician
Word & Life Church

"If you want "loud", then run a piece of sheet metal through a table saw------

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David Buckley

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Re: Fluorescent lights causing hum bars on VGA line
« Reply #25 on: September 01, 2017, 09:58:00 am »

Really, it's a single pole, double-throw switch (SPDT). But what is the universal term for a 4-way switch?

"Intermediate"

An intermediate switch is, of course, no more than a DPDT switch cross-wired.

One of these in a box with a couple of speakons is a real easy way to track down phase errors in speakers or the wiring thereof. 
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