Posted by mike on May 24, 2012, 9:55 pm
On 5/24/2012 2:26 PM, Jim Wilkins wrote:
Been there, done that.
I built a few gizmos for a guy. Did it as an investment.
He was a bright guy with a lot of ideas. I wanted to be
there if he ever had a marketable one.
I'm amazed by the number of people who spend years and post
videos for free energy devices without ever measuring anything.
And the few that have a meter, don't measure energy.
There oughta be a how-to guide for measuring power/energy,
but I'm too lazy to go look for it...but it'd probably cause
youtube to implode on itself.
Posted by Jim Wilkins on May 24, 2012, 10:47 pm
I used a $0,000 digitizing oscilloscope and $000 DC current probe,
and let the scope's math processor do the piecewise integration of
If you are on a home-experimenter budget with old surplus equipment,
accurate AC power measurement is quite a challenge.
Current measuring shunts like this can sometimes be found cheap in
surplus stores, but not around here because I snap them up.
Inductive and Hall effect AC current probes often have a low enough
bandwidth to misread complex waveforms. That includes Tek P6020
passive current probes.
Posted by Winston on May 24, 2012, 11:59 pm
Jim Wilkins wrote:
Rectify, filter, provide a resistive load.
Two multimeters. P=I*E, with sufficient
accuracy and precision to separate the
duds from the miracles.
Measure the power dissipated in the bridge
and the filter, to put your generator over the top,
in those rare instances where you only see
100 W out for 100 W in.
Posted by Jim Wilkins on May 25, 2012, 1:33 am
An example I have yet to do carefully is to compare the power demand
of this laptop running on a 12V auto-air adapter versus a small
12-120V inverter and the mains power supply. Their 12V battery current
draws are fairly similar as indicated by an old Weston analog DC
ammeter. The problem is that both power adapters are switchers that
don't pull steady DC current.
Metal content if this were R.C.M.: I machined a brass jack to fit the
Dell Latitude power plug, to check the overcurrent trip point.
I can swap the battery for a lab supply with nice digital meters, if I
determine how they react to pulsed load current.
I bought the last one they had at $30.
It isn't what I'm used to having on the bench
but it's close enough.
Who uses resistive loads any more?
Posted by Winston on May 25, 2012, 5:30 am
Jim Wilkins wrote:
Yeah, but we were discussing measurement of a power
source. That bit is not too difficult.
Switcher supplies are another story.
Luckily there are economical A.C. power meters available
that will read out VAR, W, Phase angle, Power Factor,
even if the load draws current in a decidedly reactive way.
I'd like a set of hollow plug gauges on a key ring
for every manufactured type of coaxial power plug.
That's a deal because they are up to $79 now, I see.
And at 10% of the cost, worth it too.
Us 'home experimenters' do.
Snazzy, but beyond the budget for sheer amateurs.
Like yours truly. :)