Maker Pro
Maker Pro

Time to get rid of the resistor.

J

John Larkin

Jan 1, 1970
0
Yes this a serious post. At some point in basic electronics you are
asked to compute the power used by a resistor. For some reason
engineers don't care if the devices they design use energy efficently.


It's been demonstrated many times that most consumers will buy cheap
stuff even if they know that a more expensive, energy-efficient gadget
would be cheaper in the long term. So an engineer is often faced with
the simple reality: design it for efficiency, and nobody will buy it.
Go step outside and see all the ugly SUVs on the street. One big SUV
will waste more energy than a million batteries.

Other constraints, like thermal issues and battery life, often make an
engineer choose a more efficient design, like a switching regulator
instead of a linear.

John
 
L

Larry Brasfield

Jan 1, 1970
0
Yes this a serious post.

Well, I'm glad you're not a troll, then.
At some point in basic electronics you are
asked to compute the power used by a resistor. For some reason
engineers don't care if the devices they design use energy efficently.

You have just unjustly slandered a great many
engineers. I am not going to educate you as
to the many ways you are wrong about that,
but I can attest to having seen many engineers
worry about how to converve power rather
than needlessly expending it. I can also see
much evidence of the same in circuits whose
designers I have never met.
Pick up some batteries off the street that some one has thrown away
they average 1.2 volts. At 1.2 volts an alkaline battery still has
about 40 percent of its energy left. Design a radio to use 4.5 volts
but takes 4 batteries. Have a circuit that uses 3 batteries at a time
while rotating the unused battery at a regular interval. Then when the
voltage of the batteries drops to 1.2 volts each the circuit switches
to using all 4 batteries in series. All the batteries can be run down
to .9 volts each where they have about 10 percent of their energy left.
This idiot circuit could have been made 100 years ago.

That would have been before the vacuum tube
was invented. Please show me the design of
your system for accomplishing such miracles.
A modern radio
would test each battery, you could then mix types of batteries in a
radio.

If this is a good idea, you should develop and
market it, then reap the rewards that accrue
from such a beneficial contribution. Once you
have worked out the implementation details
and done a market study, I would like to see it,
(under a reasonable NDA, of course).
A resistor that throws away heat is only one part of an energy
wasting device.

Very true. I have used transistors to waste
energy, even diodes and vacuum tubes. I
wonder if a transmitter antenna counts as an
energy wasting device in your world view.
Perhaps what I am thinking of is instead of a resistor
you need a current limiting device.

That would be useful, too. Resistors are often
treasured for their linear E/I relation, so I would
not abandon the energy transmogrifying resistor
too soon. But a current limiter that did not have
that nasty problem of getting hot would be quite
a boon as well. What do you suppose the cost
of these parts will be? Does that matter at all
in your scheme of things?
 
F

Fred Abse

Jan 1, 1970
0
For some reason
engineers don't care if the devices they design use energy efficently.

Tell that to Jim Lovell and Fred Haise!
 
D

Don Kelly

Jan 1, 1970
0
Larry Brasfield said:
Their technical descriptions indicate this clearly
enough that it would be fraudulent if not true.
Of course, one could assert the the energy
losses make it a gimic, and some performance
numbers would be needed to gainsay that.
---------
What is the alternative? Conventional brakes which dissipate all the KE of
the car as heat, or recovering most of the energy by charging the battery?

Not a gimmick. Regenerative braking has been in use for a long time- It is
common in many applications and was used in trolley systems long before
Toyota got into the car business.

Rather than dump all the energy into heat, you can recover a good fraction
of it (motor as generator will be about 80-90% efficient although there
will be other losses in the system and energy recovery at low speeds will
be poor- braking to a complete standstill won't occur. The system is simple
and even ignoring the energy recovery, the savings on brake wear will pay
for it.
 
D

Don Kelly

Jan 1, 1970
0
phaeton said:
Or on a similar note (to the point about transformed energy is only
wasted if you don't want it)...

Some of those very large electrical junctionboxes (look like a huge
heat sink) that you'll find in a lot of industrial parks or on the
edges of shopping centers. You know, the big green ones that buzz
loudly. iirc, they've got a huge step-down transformer in there that
is converting line voltage into something useable by industrial
equpment.

Does the gigantic transformer throw off enough electromagnetic
oscillation to energize the coils of a smaller transformer (about the
size of your fist) if it is placed nearby? Could you used this "waste"
to power anything? I've always wanted to take a small transformer and
meter up to one and see what i'd get, but with the Patriot Act and
all....
----------
No.
The external field of the transformer is pretty damned low. A coil (not
another transformer) *might* in the right configuration inside the tank and
cuddled up to the windings, produce a small open circuit voltage but the
coupling would be so poor that no useful energy could be obtained. Such
transformers are generally 3 phase with even less external field. I have
placed a bismuth spiral field detector directly on the coils of a 3KVA
transformer and got a very low indication-so low that it was useless-
couldn't even tell the difference between loaded and unloaded conditions.
The design of a transformer in the multiple KVA range and higher does
include considerable effort to reduce leakage flux as much as possible.
Consider this, if there was an appreciable field the tank of the transformer
would get bloody hot. Also, as is, there is no energy being lost in leakage
flux so you are not saving energy-why bugger up a good thing?
..
As John says- if you could do this it would be theft of energy.
Easier to steal energy by using a large loop with one side near one phase of
a major power line. And as much of a fools game as the proposal for a number
of reasons and still not an energy conserving process.[/QUOTE]
 
L

Larry Brasfield

Jan 1, 1970
0
Don Kelly said:
[Regarding Mr. Monsen's comment:]
What is the alternative? Conventional brakes which dissipate all the KE of
the car as heat, or recovering most of the energy by charging the battery?

Not a gimmick. Regenerative braking has been in use for a long time- It is
common in many applications and was used in trolley systems long before
Toyota got into the car business.

Rather than dump all the energy into heat, you can recover a good fraction
of it (motor as generator will be about 80-90% efficient although there
will be other losses in the system and energy recovery at low speeds will
be poor- braking to a complete standstill won't occur. The system is simple
and even ignoring the energy recovery, the savings on brake wear will pay
for it.

Sorry for being too subtle, there. I was actually
casting some basis for doubt of Mr. Monsen's
"may be more sales pitch than reality." If you
read my paragraph closely, you should see that.
(If I had the evidence to gainsay or support that
conjecture, I would have done so. But I lacked
such numbers and so entered that demurral.)

From what I understand of battery performance,
recharge efficiency is one of the major tent poles
in getting high braking recovery efficiency.

I recently had the opportunity to travel with an
engineer's engineer in his hybrid car. As he made
clear, there is much catering to the technophile in
those gadgets, not to mention fantastic milage. I
highly recommend the experience, although I plan
to wait for better battery lifetime and life-cycle
cost statistics to accumulate before I buy one.
 
R

Roger Johansson

Jan 1, 1970
0
phaeton said:
Does the gigantic transformer throw off enough electromagnetic
oscillation to energize the coils of a smaller transformer (about the
size of your fist) if it is placed nearby? Could you used this "waste"
to power anything? I've always wanted to take a small transformer and
meter up to one and see what i'd get, but with the Patriot Act and
all....

You could try walking by holding a fluoroscent tube at night.

Maybe you will experience something like this

http://www.boxyit.com/r/index.htm

That pictures shows 1300 fluoroscent tubes pushed into the ground under a
power line, photo taken at night. Explanations and discussions here:

http://slashdot.org/articles/04/02/22/1434230.shtml

There are actually laws against stealing electromagnetic power like this,
but a little experiment is not likely to put you in jail.
 
Thanks everyone I saw some of those LED drivers in the electronics mags
they are two small for me to soider on and still they have the resistor
in series with the LED.
 
D

Don Kelly

Jan 1, 1970
0
Larry Brasfield said:
Don Kelly said:
[Regarding Mr. Monsen's comment:]
What is the alternative? Conventional brakes which dissipate all the KE of
the car as heat, or recovering most of the energy by charging the battery?

Not a gimmick. Regenerative braking has been in use for a long time- It is
common in many applications and was used in trolley systems long before
Toyota got into the car business.

Rather than dump all the energy into heat, you can recover a good fraction
of it (motor as generator will be about 80-90% efficient although there
will be other losses in the system and energy recovery at low speeds will
be poor- braking to a complete standstill won't occur. The system is simple
and even ignoring the energy recovery, the savings on brake wear will pay
for it.

Sorry for being too subtle, there. I was actually
casting some basis for doubt of Mr. Monsen's
"may be more sales pitch than reality." If you
read my paragraph closely, you should see that.
(If I had the evidence to gainsay or support that
conjecture, I would have done so. But I lacked
such numbers and so entered that demurral.)

From what I understand of battery performance,
recharge efficiency is one of the major tent poles
in getting high braking recovery efficiency.

I recently had the opportunity to travel with an
engineer's engineer in his hybrid car. As he made
clear, there is much catering to the technophile in
those gadgets, not to mention fantastic milage. I
highly recommend the experience, although I plan
to wait for better battery lifetime and life-cycle
cost statistics to accumulate before I buy one.
------
Sorry, Larry- I do realise what you were doing and I agree with you in that
the battery and its recharge efficiency is a major problem along with the
energy density and lifetime problems. As for life cycle, there is a cab
driver in Vancouver BC whose older Prius was replaced after over 200,000
trouble free km by a new one (Toyota was going to tear the old one apart to
check all components for wear, etc). He has now retired it to personal use
and bought another for business so it appears that at least one person is
very happy with the hybrid (which, in my mind, considering batteries etc, is
still preferrable to all electric where the problems that you refer to are
more serious.)
 
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