Energizer Coil - unsual behaviour ?

[baroutologos]

Hello again,
It seems I am a guy full of questions. Ok this thread goes for the Energizer coil at top of my SSG.

I had been inspired by Rick Friedrich's SSG self runner setup (not likely) and i had mounted on top of my SSG a 55 ohms 24 agw coil. My rotor back then was composed of 18 magnets in alternating polarity doubled stacked.

Coil at SSG's 250 rpm was outputed some 40 volts ac and had a 80mA current when shorted.

The peculiar thing
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I had repeatedly verified that if i applied a FWBR and spin the wheel (250rpm), my 460uf electrolytic cap would charge in 4-5 secs at 90 volts!

How can be possible? 40 volts ac to charge a cap to 90?

I had also noticed that the cap would charge at 90v or somewhere there no matter what the rpm of the rotor or the energizer's coil nominal voltage.
It could charge to 90volts even though the rotor was barely rotated.
BUT... if slow moving, it would take a far longer time to reach 90 volts.

By increasing RPM, cap would level some 90 vac but get there quite faster.

My question
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How can a cap could be charged (and hold the charge) in a higher value from a coil - AFTER a FWBR ???

Regards,
Baroutologos

[gyula]

Hi,

To arrive at the answer, we should know the followings:

How accurate the 40V AC across the coil ends, it is an effective RMS value, right? You believe in your meter that reads 40V, don't you. Checked it with a scope?

The peak value of 40V RMS is 56.5V and this is normally a capacitor is charged up to the peak value of the rectified AC when you use it as an unloaded puffer capacitor.

If you measure 90V DC voltage in the 460uF capacitor, after a full wave rectifier, then your input AC amplitude is in question. It must be higher than 40V RMS. Its waveform shape is sinusoid-like?

rgds, Gyula

[baroutologos]

Unfortunately Guyla I have not a scope, neither i know how to operate it.

Nevertheless, my DMM is a faily good one - not cheap - and can measure 40 volts with some accuracy i could say...
Yes 40 volts ac is a rms value - 56 peak to peak.

Again, as i POINTED OUT, the cap can be charged to 90 volts whereas the wheel is just turning! That means the coil just outputs some 5-10 volts, but it takes longer than full speed.

I am not the mustify type of person... there must be a logical, plain explanation about that. I just do not know it yet. I hope you guy have some same experience and enlighten me a bit

Regards,
Baroutologos

[CosmicFarmer]

Any time there is HV and COIL in a sentence, I always blame that on inductive flyback. Meters, both AC and DC will average out that pulse. Thats why you need a scope, because it shows you the peak. That peak voltage from 12 volt source might be any voltage based on the charge time and coil dimensions. My SSG coil with 12 volt input on the one magnet generator was filling a capacitor up to above 90 volts in less then a second on the trigger wire (when charging battery was removed).

The non-mystifying explanation is the electrons form a field around the coil as they enter it. Once the field is established, then they can travel through unimpeded. Once the current snaps off, that field dives into the coil and manifests as electrons going the other way, violently, for a split second. Meters might not be able to measure this, even good ones. Especially anything that does RMS averaging. It will simply manifest to you as a slightly higher reading.

Whats the average of 10, 10, 10, 10, 10, 10, and 70? a little less then 20. If your tool removes for your convenience any line static or noise, then it will ignore the 70 and give you just 10.

A scope you hook up like any meter, between 2 reference points. The TV display will give you a time/volts display, at different time and voltage magnitudes. The scope won't miss the peak. It might miss the top, and only show you the fall of the pulse back to normal, but you will know something happened there.

If that's not why, then I would have to really look at your setup to know.

I got one scope for 40$ off ebay. My clamp ammeter from the store cost more.
Cheers

[CosmicFarmer]

Sorry for the second post but I forgot something.

If you don't have a scope an easy way to find out how tall your peaks are is get a low farad high volt cap and hook it in to your circuit, and the caps will charge up to the peak's value. I'm still learning charge times, but I'm sure one pulse into a cap won't bring the whole cap up to the pulse voltage, but enough will.

Also if there is any switching element energized by the magnet's passage through the coil, such as the SSG, that action might cause an inductive collapse even on a small scale, enough to get your high volts.

Plus, your AC waveform from alternating magnet positioning might stress the coil more then the standard north out pulsed DC, but I'm not sure.

Try to see, cut your coil out of your circuit and then check the volts with your meter and cap. Just coil and magnets, might make more classic sense, but that transistor or switch really adds another dimension to it.

[gyula]

...
Yes 40 volts ac is a rms value - 56 peak to peak.

Hi,

May I correct it: 56 is NOT peak to peak value of 40V RMS but it is the peak value, ok? The peak to peak value would be 40*2.82=112.8V (assuming you have a nearly sinusoid and symmetrical waveform).

I agree with CosmicFarmer on making a a simple half wave rectifier with one fast diode and a few uF (say any value from 1 or max 4.7uF) capacitor to check the real positive or negative peak values of your waveform, especially now that you do not have an oscilloscope. Make sure the working voltage of this low value cap should have at least 250V or rather over 300V DC rating, ok?

rgds, Gyula

[baroutologos]

SOrry, my typo! 56 peak value - no peak to peak -!

Unfortunately i do not possess it anymore. Energizer coil, as well as NSNS SSG has passed into recycling stage
Ok, i see this observation should not happened normally...

I will classify it as question mark and go on with my reaserch. If i meet again the same situation i will conduct the tests you guys proposed.

You have been great help anyway. Thanks dudes!

Regards,
Baroutologos