Infant Mortality battery tester

[JaBrIoL]

All,

Here is another interesting project,
I am to build a infant mortality battery tester.

the tester is to be designed to a 110amp load

for a 12 volt 16amp battery (the battery is actually capable of
putting out 110amps for 16 seconds)

Hence after a 6 second with a load attached, the battery should
recover and measure 9.6 volts.

running the numbers I came with

resistor= .109 at 1.32KW

Yes I know, why not lay a bare wire over the darn thing..?
crude simple and effective which may cause personal injury burns, etc,
blah,blah lawsuit. I think I will go with a test fixture. So far It
has become difficult to locate a manufacturer for this type of
resistor.

I've been throwing around other... a resistor in a can of mineral oil
etc.. (the ole dummyload)

any ideas or suggestions?

 

[Tim Wescott]

Use resistance wire and make up your own resistor, suitably shielded. You
shouldn't have to mess with immersing it unless you want to. Pay attention
to the resistance change of the wire as it heats up (immersion would help
here), and design your mechanical arrangement accordingly.

If you need a precise current then switch in a number of individual segments
in parallel, or use the wire to absorb the first 700-800 watts and a (well
heatsunk!) transistor load to control the current.

"JaBrIoL" <Jabriol@excite.com> wrote in message
news:d222de3e.0402200838.3491976f@posting.google.com...

All,

Here is another interesting project,
I am to build a infant mortality battery tester.

the tester is to be designed to a 110amp load

for a 12 volt 16amp battery (the battery is actually capable of
putting out 110amps for 16 seconds)

Hence after a 6 second with a load attached, the battery should
recover and measure 9.6 volts.

running the numbers I came with

resistor= .109 at 1.32KW

Yes I know, why not lay a bare wire over the darn thing..?
crude simple and effective which may cause personal injury burns, etc,
blah,blah lawsuit. I think I will go with a test fixture. So far It
has become difficult to locate a manufacturer for this type of
resistor.

I've been throwing around other... a resistor in a can of mineral oil
etc.. (the ole dummyload)

any ideas or suggestions?

 

[Mjolinor]

"Tim Wescott" <tim@wescottnospamdesign.com> wrote in message
news:103cfjkcl24lk99@corp.supernews.com...

Use resistance wire and make up your own resistor, suitably shielded. You
shouldn't have to mess with immersing it unless you want to. Pay
attention
to the resistance change of the wire as it heats up (immersion would help
here), and design your mechanical arrangement accordingly.

If you need a precise current then switch in a number of individual
segments
in parallel, or use the wire to absorb the first 700-800 watts and a (well
heatsunk!) transistor load to control the current.

"JaBrIoL" <Jabriol@excite.com> wrote in message
news:d222de3e.0402200838.3491976f@posting.google.com...
All,

Here is another interesting project,
I am to build a infant mortality battery tester.

the tester is to be designed to a 110amp load

for a 12 volt 16amp battery (the battery is actually capable of
putting out 110amps for 16 seconds)

Hence after a 6 second with a load attached, the battery should
recover and measure 9.6 volts.

running the numbers I came with

resistor= .109 at 1.32KW

Yes I know, why not lay a bare wire over the darn thing..?
crude simple and effective which may cause personal injury burns, etc,
blah,blah lawsuit. I think I will go with a test fixture. So far It
has become difficult to locate a manufacturer for this type of
resistor.

I've been throwing around other... a resistor in a can of mineral oil
etc.. (the ole dummyload)

any ideas or suggestions?

Buy a commercial lead acid battery tester or two and nick the resistance
element out of them.

 

[Ben Bradley]

In sci.electronics.design, Jabriol@excite.com (JaBrIoL) wrote:

All,

Here is another interesting project,
I am to build a infant mortality battery tester.

Yes I know, why not lay a bare wire over the darn thing..?

any ideas or suggestions?

http://elecdesign.com/Articles/Index.cfm?ArticleID=2144

-----
http://mindspring.com/~benbradley

 

[Fritz Schlunder]

"JaBrIoL" <Jabriol@excite.com> wrote in message
news:d222de3e.0402200838.3491976f@posting.google.com...

All,

Here is another interesting project,
I am to build a infant mortality battery tester.

the tester is to be designed to a 110amp load

for a 12 volt 16amp battery (the battery is actually capable of
putting out 110amps for 16 seconds)

Hence after a 6 second with a load attached, the battery should
recover and measure 9.6 volts.

running the numbers I came with

resistor= .109 at 1.32KW

Yes I know, why not lay a bare wire over the darn thing..?
crude simple and effective which may cause personal injury burns, etc,
blah,blah lawsuit. I think I will go with a test fixture. So far It
has become difficult to locate a manufacturer for this type of
resistor.

I've been throwing around other... a resistor in a can of mineral oil
etc.. (the ole dummyload)

any ideas or suggestions?

If this were up to me I would take a large plastic bucket, such as a 40 lb.
laundry detergent bucket, and fill it with water. 12V is quite low and even
with highly salty (like ocean water) water the current flow through water
will be very small compared to the 110A or whatnot. It will also be quite
safe to play with at 12V.

Once filled with water I would go here:

http://www.mogami.com/e/cad/wire-gauge.html

And find out what the resistance of some different wires are. I would
probably use something like 18 AWG copper wire for this job. From the
calculator we see the DC resistance is 20.9mOhm per meter. So you want
109mOhm, so about 109/20.9 = 5.2 meters. I would get this length of
uninsulated or plain magnet wire and place this inside the plastic bucket of
water. I would make sure to make good connections on the ends with
something like 2 AWG wire leading to the battery terminals so that all the
18AWG wire is fully immersed in the water.

Voila. 0.109 Ohm resistor at 1.32kW. Cost may be nothing out of pocket if
you have this stuff laying around. If I wanted to store it for any length
of time I would make sure to include a lid for the bucket as well as putting
something in the water like antifreeze to make sure algae and other
biologics don't grow out of control in the water.

 

[Jerry G.]

If you want something calibrated and engineered for you that is safe, buy a
commercial high power battery tester. All the automotive places that do auto
electrics will have these. They are not extremely expensive for what goes
in to them. The ones that I have seen have a variable loading on them, and
you can measure the point at which the battery starts to go down. You can
then determine an exact measurement of the battery condition that would be
repeatable, and accurate. The very high end ones use an actual variable type
resistor assy that is properly rated. It works through a bridged loading
with the amp and volt meters. This affair gives a very concise reading.

If you want to mess around, you can start by using nichrome heating element
wire to make your resistors. Use many in parallel to take up the load, and
to also be able to have low resistance with more mass, thus giving better
stability. Remember, as this heats up, its resistance will also change, thus
not making the readings linear. The commercial units are worked out to
compensate for this.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"JaBrIoL" <Jabriol@excite.com> wrote in message
news:d222de3e.0402200838.3491976f@posting.google.com...
All,

Here is another interesting project,
I am to build a infant mortality battery tester.

the tester is to be designed to a 110amp load

for a 12 volt 16amp battery (the battery is actually capable of
putting out 110amps for 16 seconds)

Hence after a 6 second with a load attached, the battery should
recover and measure 9.6 volts.

running the numbers I came with

resistor= .109 at 1.32KW

Yes I know, why not lay a bare wire over the darn thing..?
crude simple and effective which may cause personal injury burns, etc,
blah,blah lawsuit. I think I will go with a test fixture. So far It
has become difficult to locate a manufacturer for this type of
resistor.

I've been throwing around other... a resistor in a can of mineral oil
etc.. (the ole dummyload)

any ideas or suggestions?

 

[Robert Baer]

JaBrIoL wrote:

All,

Here is another interesting project,
I am to build a infant mortality battery tester.

the tester is to be designed to a 110amp load

for a 12 volt 16amp battery (the battery is actually capable of
putting out 110amps for 16 seconds)

Hence after a 6 second with a load attached, the battery should
recover and measure 9.6 volts.

running the numbers I came with

resistor= .109 at 1.32KW

Yes I know, why not lay a bare wire over the darn thing..?
crude simple and effective which may cause personal injury burns, etc,
blah,blah lawsuit. I think I will go with a test fixture. So far It
has become difficult to locate a manufacturer for this type of
resistor.

I've been throwing around other... a resistor in a can of mineral oil
etc.. (the ole dummyload)

any ideas or suggestions?

I take it that what you mean by "a 12 volt 16amp battery" is that it
has a 16 Amp-Hour rating.
Therefore, a 110 amp load is *abusive*; look at the quote from
Interstate Batteries!
The spec from Interstate Batteries is: "If the battery can sustain a
load equal to 2 times the Amp-Hour capacity, holding a voltage of at
least 10.5 volts for 5 seconds, then the battery should be considered
structurally sound." NOTE: the voltage mentioned is read *during* the
load time.

Some testing procedures for heavy duty automotive and/or marine
batteries (type not specified in the literature) mentions a 300 amp load
for 15 seconds, but that clearly is not commensurate with your
application or battery type/design.
Looking at a lot of literature, i find that the 10.5V specification as
being the most realistic; i suggest that you modify that 9.6V limit and
also the reading method.
A battery that cannot recover to full voltage is either not good or
has been subjected to an abusive load, which can shorten its life
expectancy at minimum, or create internal damage.

If the battery is useable, then the current will be constant for the
purposes of the test, and if it is bad, then it does not matter that the
voltage and current drops a lot.
I have tested over a hundred reject batteries, some were useable for
non-medical purposes (they were from motorized wheel chairs and
scooters) as-found, and some were recoverable for non-medical purposes.

**
There are automotive car battery load testers, and some of them are
portable.
They include a voltmeter, a resistive load in the region of interest,
and heavy duty leads with heavy duty clips.
That load resistor and its enclosure can be very useful for making of
a suitable tester.
Harbor Freight or other "discounter" (read: seller of Chinese made
stuff) has such an item that is not too expensive for either casual or
serious use.

 

[Robert Baer]

Ben Bradley wrote:

In sci.electronics.design, Jabriol@excite.com (JaBrIoL) wrote:

All,

Here is another interesting project,
I am to build a infant mortality battery tester.

Yes I know, why not lay a bare wire over the darn thing..?

any ideas or suggestions?

http://elecdesign.com/Articles/Index.cfm?ArticleID=2144

-----
http://mindspring.com/~benbradley

....and pray tell, what the hell does guitars have to do with the subject
at hand?

 

[.]

"JaBrIoL" <Jabriol@excite.com> wrote in message
news:d222de3e.0402200838.3491976f@posting.google.com...

All,

Here is another interesting project,
I am to build a infant mortality battery tester.

the tester is to be designed to a 110amp load

for a 12 volt 16amp battery (the battery is actually capable of
putting out 110amps for 16 seconds)

Hence after a 6 second with a load attached, the battery should
recover and measure 9.6 volts.

running the numbers I came with

resistor= .109 at 1.32KW

Yes I know, why not lay a bare wire over the darn thing..?
crude simple and effective which may cause personal injury burns, etc,
blah,blah lawsuit. I think I will go with a test fixture. So far It
has become difficult to locate a manufacturer for this type of
resistor.

I've been throwing around other... a resistor in a can of mineral oil
etc.. (the ole dummyload)

any ideas or suggestions?

I saw a construction article in either Radio Electronics or Popular
Electronics during the 1980s for a battery tester capable of loading a car
battery. I received these magazines starting in 1982. They used a specific
length of 1/2 inch steel strapping that was wound around dowels on a wooden
base. The article can be found at the library if anyone is interested.

Ken

 

[BFoelsch]

Resistors in the rating area you describe are used in the electric power
industry.

I don't know if they still make them, but as of my last association with
them the Square D Company made several lines of resistors for similar use,
crane and hoist speed control and braking, etc. One model was known as the
PX resistor and were of nichrome on ceramic construction. and quite low in
cost. If that product line still exists I am sure they could provide
something suitable. Post-Glover is another manufacturer of industrial power
resistors.

"." <t@donotemailme.com> wrote in message
news:ERUZb.20751$C6.6607@fe22.usenetserver.com...

"JaBrIoL" <Jabriol@excite.com> wrote in message
news:d222de3e.0402200838.3491976f@posting.google.com...
All,

Here is another interesting project,
I am to build a infant mortality battery tester.

the tester is to be designed to a 110amp load

for a 12 volt 16amp battery (the battery is actually capable of
putting out 110amps for 16 seconds)

Hence after a 6 second with a load attached, the battery should
recover and measure 9.6 volts.

running the numbers I came with

resistor= .109 at 1.32KW

Yes I know, why not lay a bare wire over the darn thing..?
crude simple and effective which may cause personal injury burns, etc,
blah,blah lawsuit. I think I will go with a test fixture. So far It
has become difficult to locate a manufacturer for this type of
resistor.

I've been throwing around other... a resistor in a can of mineral oil
etc.. (the ole dummyload)

any ideas or suggestions?

I saw a construction article in either Radio Electronics or Popular
Electronics during the 1980s for a battery tester capable of loading a car
battery. I received these magazines starting in 1982. They used a specific
length of 1/2 inch steel strapping that was wound around dowels on a
wooden
base. The article can be found at the library if anyone is interested.

Ken

 

[Roger Lascelles]

We manufacture a unit which draws up to 450 amps out of 12V automotive
batteries for around the time you require. Our load is about a stainless
steel bar, roughly 1200 mm long, 20 mm x 5 mm cross section. Its easy to
slide a contact (such as a heavy duty battery clip) along the bar to get the
current you need.

Stainless steel has a pretty high temperature coefficient, but the exact
current does not matter to us - and I suspect the current does not have to
be precise for your application.

For high duty cycle use, we use a small computer type cooling fan to move
some air over the bar. At only 110 amps, you shouldn't have nearly so much
trouble with heat.

The battery voltage will drop under load, so you might want less resistance
than you calculate using 12V and Ohms Law.

Your test spec looks unusual to me. Even a half dead battery will recover
to above 9.6 volts when you remove the load, unless it has an internal open
circuit. The standard Battery Council International load test for Starting
Batteries is to draw 0.5 of rated Cold Cranking Amps for 15 seconds - the
voltage should remain above 9.6 volts while the load is applied. Test
temperature 18 degrees F.

Roger



"." <t@donotemailme.com> wrote in message
news:ERUZb.20751$C6.6607@fe22.usenetserver.com...

"JaBrIoL" <Jabriol@excite.com> wrote in message
news:d222de3e.0402200838.3491976f@posting.google.com...
All,

Here is another interesting project,
I am to build a infant mortality battery tester.

the tester is to be designed to a 110amp load

for a 12 volt 16amp battery (the battery is actually capable of
putting out 110amps for 16 seconds)

Hence after a 6 second with a load attached, the battery should
recover and measure 9.6 volts.

running the numbers I came with

resistor= .109 at 1.32KW

Yes I know, why not lay a bare wire over the darn thing..?
crude simple and effective which may cause personal injury burns, etc,
blah,blah lawsuit. I think I will go with a test fixture. So far It
has become difficult to locate a manufacturer for this type of
resistor.

I've been throwing around other... a resistor in a can of mineral oil
etc.. (the ole dummyload)

any ideas or suggestions?

I saw a construction article in either Radio Electronics or Popular
Electronics during the 1980s for a battery tester capable of loading a car
battery. I received these magazines starting in 1982. They used a specific
length of 1/2 inch steel strapping that was wound around dowels on a
wooden
base. The article can be found at the library if anyone is interested.

Ken

 

[JaBrIoL]

"Mjolinor" <mjolinor@hotmail.com> wrote in message news:<xwrZb.27$3B5.3@newsfe1-win>...

Buy a commercial lead acid battery tester or two and nick the resistance
element out of them.

We have one. However Hawker Genesis, belives that many of the reading
from their
lead battery might be erroneous. these batteries lead-accid are not in
the sense lead acid batteries, they are more like Lead asorb by tin
batteries.

the test I described, is recommended by them.

 

[JaBrIoL]

Robert Baer <robertbaer@earthlink.net> wrote in message news:<40370CC2.8FBCBB21@earthlink.net>...

JaBrIoL wrote:

All,

Here is another interesting project,
I am to build a infant mortality battery tester.

the tester is to be designed to a 110amp load

for a 12 volt 16amp battery (the battery is actually capable of
putting out 110amps for 16 seconds)

Hence after a 6 second with a load attached, the battery should
recover and measure 9.6 volts.

running the numbers I came with

resistor= .109 at 1.32KW

Yes I know, why not lay a bare wire over the darn thing..?
crude simple and effective which may cause personal injury burns, etc,
blah,blah lawsuit. I think I will go with a test fixture. So far It
has become difficult to locate a manufacturer for this type of
resistor.

I've been throwing around other... a resistor in a can of mineral oil
etc.. (the ole dummyload)

any ideas or suggestions?

I take it that what you mean by "a 12 volt 16amp battery" is that it
has a 16 Amp-Hour rating.
Therefore, a 110 amp load is *abusive*; look at the quote from
Interstate Batteries!
The spec from Interstate Batteries is: "If the battery can sustain a
load equal to 2 times the Amp-Hour capacity, holding a voltage of at
least 10.5 volts for 5 seconds, then the battery should be considered
structurally sound." NOTE: the voltage mentioned is read *during* the
load time.

Thanks, the 110 amp load I got.. was from Hawker Genesis. they belive
if I went over 15 seconds, it would be abusive to their batteries.

interesting however, they would want me to do a voltage read after the
load test. If the battery recover to 9.6 volts, they consider it a
good battery.

I Like your suggestion though, I consider it a bit more safe.

 

[JaBrIoL]

"Roger Lascelles" <r.o.g.e.r.l.a.s.@optusnet.com.au.removedots> wrote
in >

Your test spec looks unusual to me. Even a half dead battery will

recover

to above 9.6 volts when you remove the load, unless it has an internal open
circuit.

that is the purpose of the test.. hence looking for infant mortality
of the batteries in quextion. It seem that ther manufacturer does not
confide mich in many battery testers. I am assuming that they have
high turn over rate of failed batteries, that when is returned, by
their standards is good. This creates a logistical problem, I intended
to avoid on my end.

 

[Robert Baer]

JaBrIoL wrote:

Robert Baer <robertbaer@earthlink.net> wrote in message news:<40370CC2.8FBCBB21@earthlink.net>...
JaBrIoL wrote:

All,

Here is another interesting project,
I am to build a infant mortality battery tester.

the tester is to be designed to a 110amp load

for a 12 volt 16amp battery (the battery is actually capable of
putting out 110amps for 16 seconds)

Hence after a 6 second with a load attached, the battery should
recover and measure 9.6 volts.

running the numbers I came with

resistor= .109 at 1.32KW

Yes I know, why not lay a bare wire over the darn thing..?
crude simple and effective which may cause personal injury burns, etc,
blah,blah lawsuit. I think I will go with a test fixture. So far It
has become difficult to locate a manufacturer for this type of
resistor.

I've been throwing around other... a resistor in a can of mineral oil
etc.. (the ole dummyload)

any ideas or suggestions?

I take it that what you mean by "a 12 volt 16amp battery" is that it
has a 16 Amp-Hour rating.
Therefore, a 110 amp load is *abusive*; look at the quote from
Interstate Batteries!
The spec from Interstate Batteries is: "If the battery can sustain a
load equal to 2 times the Amp-Hour capacity, holding a voltage of at
least 10.5 volts for 5 seconds, then the battery should be considered
structurally sound." NOTE: the voltage mentioned is read *during* the
load time.


Thanks, the 110 amp load I got.. was from Hawker Genesis. they belive
if I went over 15 seconds, it would be abusive to their batteries.

interesting however, they would want me to do a voltage read after the
load test. If the battery recover to 9.6 volts, they consider it a
good battery.

I Like your suggestion though, I consider it a bit more safe.

I suggest that you view my response and quote from Interstate.
A load of 100 amps *is* abusive on those poor little batteries, and
the spec is a higher voltage *during* load.

 

[Robert Baer]

JaBrIoL wrote:

"Roger Lascelles" <r.o.g.e.r.l.a.s.@optusnet.com.au.removedots> wrote
in

Your test spec looks unusual to me. Even a half dead battery will
recover
to above 9.6 volts when you remove the load, unless it has an internal open
circuit.

that is the purpose of the test.. hence looking for infant mortality
of the batteries in quextion. It seem that ther manufacturer does not
confide mich in many battery testers. I am assuming that they have
high turn over rate of failed batteries, that when is returned, by
their standards is good. This creates a logistical problem, I intended
to avoid on my end.

A 100 amp load can *create* "infant mortality" of the batteries due to
excessive internal heating created by the massive current.
Might as well put a #0000 silver busbar wire across the terminals and
let the battery melt or explode.
If a battery melts or explodes in those conditions, then it *WAS*
good; if not, it was (and is) bad.
Sort of like the joke about testing fuses.

 

[JaBrIoL]

Robert Baer <robertbaer@earthlink.net> wrote in message news:<403B1826.C128223A@earthlink.net>...

JaBrIoL wrote:

"Roger Lascelles" <r.o.g.e.r.l.a.s.@optusnet.com.au.removedots> wrote
in

Your test spec looks unusual to me. Even a half dead battery will
recover
to above 9.6 volts when you remove the load, unless it has an internal open
circuit.

that is the purpose of the test.. hence looking for infant mortality
of the batteries in quextion. It seem that ther manufacturer does not
confide mich in many battery testers. I am assuming that they have
high turn over rate of failed batteries, that when is returned, by
their standards is good. This creates a logistical problem, I intended
to avoid on my end.

A 100 amp load can *create* "infant mortality" of the batteries due to
excessive internal heating created by the massive current.
Might as well put a #0000 silver busbar wire across the terminals and
let the battery melt or explode.
If a battery melts or explodes in those conditions, then it *WAS*
good; if not, it was (and is) bad.
Sort of like the joke about testing fuses.

Oh I know... hence my comment on the original post about laying a bare
wire across.

however the manufacturer claims that it can hold 110amp load for 15
seconds.
16 seconds would be abusive. figure that one out. I think I might go
a differnt route all together.

 

[JaBrIoL]

"Roger Lascelles" <r.o.g.e.r.l.a.s.@optusnet.com.au.removedots> wrote in message news:<4039627a$0$19707$afc38c87@news.optusnet.com.au>...

We manufacture a unit which draws up to 450 amps out of 12V automotive
batteries for around the time you require. Our load is about a stainless
steel bar, roughly 1200 mm long, 20 mm x 5 mm cross section. Its easy to
slide a contact (such as a heavy duty battery clip) along the bar to get the
current you need.

got a website? distributors in the states?

 

[Watson A.Name \"Watt Sun]

JaBrIoL wrote:

All,

Here is another interesting project,
I am to build a infant mortality battery tester.

the tester is to be designed to a 110amp load

for a 12 volt 16amp battery (the battery is actually capable of
putting out 110amps for 16 seconds)

Hence after a 6 second with a load attached, the battery should
recover and measure 9.6 volts.

running the numbers I came with

resistor= .109 at 1.32KW

Yes I know, why not lay a bare wire over the darn thing..?
crude simple and effective which may cause personal injury burns, etc,
blah,blah lawsuit. I think I will go with a test fixture. So far It
has become difficult to locate a manufacturer for this type of
resistor.

I've been throwing around other... a resistor in a can of mineral oil
etc.. (the ole dummyload)

any ideas or suggestions?

I would consider using several auto headlamps. The usual headlamp draws
something like 20 amps or so, and they're relatively cheap. They don't
need a big heatsink nor mineral oil, so you're way ahead in that respect.

 

[mike]

Watson A.Name \"Watt Sun - the Dark Remover\" wrote:

JaBrIoL wrote:

All,


Here is another interesting project,
I am to build a infant mortality battery tester.


the tester is to be designed to a 110amp load


for a 12 volt 16amp battery (the battery is actually capable of
putting out 110amps for 16 seconds)


Hence after a 6 second with a load attached, the battery should
recover and measure 9.6 volts.


running the numbers I came with


resistor= .109 at 1.32KW


Yes I know, why not lay a bare wire over the darn thing..?
crude simple and effective which may cause personal injury burns, etc,
blah,blah lawsuit. I think I will go with a test fixture. So far It
has become difficult to locate a manufacturer for this type of
resistor.


I've been throwing around other... a resistor in a can of mineral oil
etc.. (the ole dummyload)


any ideas or suggestions?


I would consider using several auto headlamps. The usual headlamp draws
something like 20 amps or so, and they're relatively cheap. They don't
need a big heatsink nor mineral oil, so you're way ahead in that respect.

That's some hummer 240W lamp. The H6054 is rated at 65/35W on 12V systems.
mike

--
Return address is VALID.
Bunch of stuff For Sale and Wanted at the link below.
Toshiba & Compaq LiIon Batteries, Test Equipment
Honda CB-125S $800 in PDX
TEK Sampling Sweep Plugin and RM564
Tek 2465 $800, ham radio, 30pS pulser
Tektronix Concept Books, spot welding head...
http://www.geocities.com/SiliconValley/Monitor/4710/