🚀 go-pugleaf

	Since this article deals with construction of an effective, but low
cost surge protector, I have cross-posted to some other newsgroups.  I have
always felt that surge protectors are sold at an artificially high price and
represent a consumer ripoff; here is a way to fight back...

In article <1805@ukecc.engr.uky.edu>, edward@engr.uky.edu (Edward C. Bennett) writes:
> >Does anybody know of any *cheap* power conditioning which might
> >significantly improve my 3B1's chances of survival?  Thanks. 
> 
> Now that I've got a 3B1, I've been concerned about power problems also.
> What are the important things to look for? Spike/surge/transient protection?
> For a start, I pulled out the ol' Radio Shack catalog. They've got two
> units that seem reasonable.
> 
> 	Under "AC Outlet Voltage Spike Protectors" there's a 6-outlet
> 	power strip with noise filter and circuit breaker for $29.95.
> 
> 	Over in computer accessories there's a 2-outlet power protector
> 	with "full common and differential mode transient protection"
> 	(What is that? A fancy way of saying voltage spikes?), noise
> 	filtration and a MOV status lamp for $18.95.
> 
> Comments? Horror stories? The idea of paying $70 for one of these things
> at a "computer emporium" seems outrageous!

	Your're right; the prices of surge protectors are outrageous -
especially when you find out how much the actual surge protector components
really cost!
	Don't get ripped of - build your own surge protector.  It's really
simple, and the cost savings will astound you.  The following is a description
of how to build a surge protector which offers dual protection: (1) using
MOV's (metal oxide varistor) and (2) using a gas discharge tube. 
	You will need the following components, all manufactured by Siemens:

1 ea	3-electrode gas discharge surge protector, P/N T61-C350	  $  3.30

3 ea	Metal oxide varistor, P/N S20K130 @ $ 0.82		  $  2.46

	As you can see, your total cost for the protector elements is
$ 5.76.  Many major electronic distributors carry Siemens.  Two examples
are Hamilton-Avnet and Allied Electronics.  Allied Electronics will sell
the above mail order; they do have a minimum order of $ 25.00, but will
fill an order less than $ 25.00 for a $ 5.00 handling charge - still not
a bad deal if you can't figure out anything else to order.  Allied has
a national toll-free number of 800/433-5700.

                  _______________
AC LINE HOT_______| 15 AMP FUSE |_____________________________OUTLETS HOT
(black)           |_____________|  |            |          |  (black)
				   |            |          |
                                  MOV        ___|___       |
                                   |         | GAS |       |
EARTH GROUND_______________________|_________|PROT.|      MOV
(green)       |                    |         |_____|       |
              |__OUTLETS GROUND    |            |          |
                 (green)          MOV           |          |
                                   |            |          |
AC LINE NEUTRAL____________________|____________|__________|__OUTLETS NEUTRAL
(white)                                                       (white)

	The following design and construction notes apply:

1.	"AC line hot" = black wire = duplex outlet narrow slot
	"AC line neutral" = white wire = duplex outlet wide slot
	"AC line ground" = green wire = duplex outlet round opening

2.	Build the protector circuitry in a 2x4 electrical "handy box".  Mount
	a fuseholder in the box for a 3AG 15 amp fuse, along with a terminal
	strip to facilitate mounting the circuit elements and making necessary
	connections.  Cover the box with a blank cover plate.

3.	Feed the box with a three-wire AC line cord of at least 16 AWG; use
	of 14 AWG is preferred.  Connect a second cord to the box; this cord
	(which should be kept reasonably short) can feed a multiple-outlet
	plug strip.

4.	As an alternative to a second cord, use one or more electrical pipe
	nipples and feed additional electrical boxes which contain duplex
	outlets (much less money than a plug strip, but not as "pretty" in
	appearance).  If you use this method, run a wire to each outlet ground
	terminal instead of relying upon the the metal electrical box for
	the ground connection.

5.	Use a common point attached to the first electrical box to connect
	all ground wires; a 10-32 machine screw through the box is good.
	This common point should terminate: the power cord ground (green),
	one end of two MOV's, the center electrode of the gas tube, and
	the outlet ground (green).

6.	Insulate all leads of the MOV's and gas protector tube using plastic
	insulating sleeving.  Use 14 AWG wire for any internal connections.
	If possible, use insulated crimp terminals for connections.  Make
	certain that the MOV's and gas protector tube do not touch the metal
	box. 
	
7.	To assure maximim effectiveness of the protector circuitry, run a
	wire from a cold water pipe or ground rod and connect it to the case
	of the electrical box containing the MOV's and gas protector tube.
	Use at least 12 AWG for this wire; a smaller gauge wire will defeat
	the purpose.  While running a separate ground is not essential, surge
	protector ciruitry is more effective with a lower impedance to earth
	ground.  An auxiliary ground wire assures such a low ground impedance.
	
8.	This box contains no "idiot lights", which are really unnecessary and
	are just a sales gimmick anyhow.  Can you really imagine SEEING a
	< 10 ms energy pulse on a so-called "surge indicator" lamp? :-)

	I make no guarantee that the above circuit will protect your computer
or other electronic equipment from anything.  However, I can assure you that
the above design (if properly constructed) represents a surge protector which
is equal or superior to anything sold by Radio Shack or any other retail store.
And the do-it-yourself price is MUCH LESS than any alternative.

<>  Larry Lippman @ Recognition Research Corp., Clarence, New York
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