1 members (ale348),
302
guests, and
14
robots. |
Key:
Admin,
Global Mod,
Mod
|
|
|
Joined: Jul 2002
Posts: 8,443 Likes: 3
OP
Member
|
|
|
|
|
Joined: Feb 2003
Posts: 288
Member
|
Ben, I too shudder to think that this may once have been part of a school curriculum, but such parts were once common. Well into the '20s and possibly even later, knife switches were standard for service equipment, and cleat lampholders such as those shown here were in common use. Even today, the NEC allows cleat lampholders with exposed live parts, if they are located a minimum of 8' above the floor! Needless to say, I would never install one. And those single-pole knife switches? I visited a church in Mexico in 2001 that had those for lighting, in public areas, at customary wall-switch height!
|
|
|
|
Joined: Feb 2006
Posts: 144
Member
|
Some of the switches are single pole, the "main" switch is a double, switching both the hot and the neutral. This has one of those old, non-deadfront type rubber plugs on it, which is not polarized. I agree, I wouldn't want to install one of those lampholders, either. They are also hard to find in stores, I have noticed, although I have never tried to order them from a supply company.
|
|
|
|
Joined: Aug 2002
Posts: 1,691
Member
|
I've bought a few from Home Depot and/or Lowes; but they only sell the plastic types.
I've seen the porcelain varieties in lamp-parts stores and independent small hardware shops too.
Knife switches, while still common, are now these little plastic things, about half the size of that. Another easily found item.
|
|
|
|
Joined: Nov 2005
Posts: 827 Likes: 1
Member
|
Consider the possibility that this might have been used as a crude load bank for who knows what. You could use something like that to check regulation on a LVPS, for example. Joe
|
|
|
|
Joined: Dec 2005
Posts: 869 Likes: 4
Member
|
Quite possible it was used as a series load bank. I use 2 x 100 watt lamps parallel in series with an appliance under test, especially for radio's, tapedecks and the like to have a limiter in case of a dead short at a faulty appliance. I take one lamp out depending upon VA rating of appliance under test. I like to see the porcelain fittings, a lot more durable then the plactic c%@p we get now these days.
The product of rotation, excitation and flux produces electricty.
|
|
|
|
Joined: Oct 2004
Posts: 806
Member
|
I shudder to think of a time when this would have been part of school curriculum. I don't. In the era that this device would have been found in use, both adults and kids had more common sense and maturity. It would have been a very effective demonstration of the principles of current flow and what-not. I have always been a "tactile" type. Show me a schematic, and I can work it through with some difficulty. Show me the actual device first, then I can not only read through the schematic a lot faster, I can draw one up! Or a better example, I designed a dual-motor control with delay start for motor #2 for pipe organ blowers. I built it first, then drew out the diagram by hand after in about an hour. It would have never gotten built if I'd tried to draw it up first. I flunked chemistry in High school for the same reason. Give me the chemicals and lab supplies and I could solve any formula. Give me the book or a list on paper, I couldn't get the formulas right to save my life! Really ticked off the teacher and my parents!
Stupid should be painful.
|
|
|
|
Joined: Nov 2005
Posts: 827 Likes: 1
Member
|
I guess this a little off topic but concerns how people think about things. Several years ago I was sent a file named "brain.exe" You answer a series of questions and it performs an analysis. Everyone at work gave it a shot and found it to be interesting. If anyone wants to check it out, email me and I will attach it to a reply. Joe
|
|
|
|
Joined: Feb 2006
Posts: 144
Member
|
You all bring up a good point I hadn't thought of. Assuming that you are cautiouss and do not touch any live parts, this wouldn't be that bad. I am mostly thinking of people I went to school with who would grab part of it "just to see what would happen" An electronics/electrical class can be very scary sometimes.
|
|
|
|
Joined: Dec 2001
Posts: 2,498
Member
|
I imagine something like that being on a teacher's desk, with the students watching from some ten feet away.
|
|
|
Posts: 28
Joined: February 2011
|
|
|
|