Driver to drive?

[JM]

On 21/11/2015 11:03, Clifford Heath wrote:

On 21/11/15 12:41, Phil Hobbs wrote:
What frequency range?
AADE rf LCR

I have an AADE-type one that I built from a kit, pretty happy with it.

However, I still envy my friend's much more versatile and accurate
DE-5000. You can find those on EBay and Aliexpress stores.

Clifford Heath.

Another thumbs up for the DE-5000. At $100 nothing else comes close.

 

[Jeff Liebermann]

On Sat, 21 Nov 2015 13:37:46 -0500, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

It's very difficult to come up with names that don't create unwanted
associations in the mind (of a native speaker).

Then, there are companies that are cheap, lazy, or both.
A123 battery company was forced to change its name as part of the
buyout deal and became B456:
<http://www.forbes.com/sites/kaipetainen/2013/03/28/battery-company-changes-name-from-a123-to-b456-a-fire-extinguisher/>
Apparently, they didn't want to waste any money finding a new name for
essentially a place holder. Too bad a B456 is actually a fire
extinguisher.
<http://www.amerexfireextinguishers.com/html/abc_.html>
Seeing a pattern here, I Googled for C789 and found a Fluke meter:
<http://en-us.fluke.com/products/all-accessories/fluke-c789.html>
Meanwhile, one of the founders of the original A123 company formed a
new battery company, 24M to make cheaper LiIon cells:
<http://24-m.com>


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jan Panteltje]

On a sunny day (Sat, 21 Nov 2015 09:53:48 -0800) it happened Jeff Liebermann
<jeffl@cruzio.com> wrote in <b4a15bdprkj42q39rkv10vvdhlsdp27a8d@4ax.com>:

On Sat, 21 Nov 2015 08:15:30 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

According to the "real" UltraFire web pile, they didn't make cells
over 3000 ma-hr, making your 3200 ma-hr cell a genuine counterfeit.

But, it gets the work done, if it was made of chewing gum and kept my flashlight working I would be happy too,
even if it had only a picture of Mickey Mouse on it.

What you are probably buying are 1000 ma-hr 18650 cells marked with
whatever the vendor thinks will sell. The cell is good enough for
most things, but not if you're trying to squeeze every last coulomb
out of the cell, as in quadcopters or flashlights. They're probably
just fine for your instrument experiments, eBikes, and vapo-smog
generators. I'm not sure about the number of charge cycles on these
batteries. It's my understand (possibly wrong) that cell design can
optimize capacity or charge cycles, but not both.

I get many things from China that look like 'home made',
for example the 1 Ah lipos with Varta on it, I am still not sure it really _is_ Varta,
but... 300 charge / discharge (90 %) cycles later I see a slight decrease in capacity.
reasonable for a lipo...

At 90% discharge, you should be killing those batteries. At what
terminal voltage do you stop brutalizing those batteries? See Fig 2:
http://www.mdpi.com/1996-1073/7/9/5995/htm
10% would be about 3.50V.

Eh, let's see, from asm source:
; Lipo battery cutoff voltage in mV
#define BATTERY_LOW_CUTOFF_VOLTAGE D'3100'

; Display will warn at this battery voltage level that battery needs charging
#define BATTERY_LOW_WARNING_VOLTAGE D'3200'

This is what I measured on the 'Varta' marked lipos:
http://panteltje.com/pub/lipo_discharge_curve_low_drop_out_regulator.gif
You will note that from warning at 3.2 V to switch-off at 3.1 V only takes a minute or less...
It crapped out once this week (am not always around to see warnings).
Don't remember the discharge current.

Now that you mention this I will try in a test-setup at a modest current (maybe 1 A) how long these new ones last.
I like your big heatsink with fan battery test setup.

For extra fun, run a frequency scan of your LiIon battery and watch it
age:
http://batteryuniversity.com/learn/article/testing_lithium_based_batteries
I haven't done this but plan to throw together something to do it,
some day, later, maybe...

The difference at the peak is only about 20/28 or 71%...

Its just a consumable...

Money is also a consumable. Whatever works for you, as long as it
doesn't become a collectable, which is responsible for my mess.

Because I did see that decrease, and these need to run 12 hours a day,
(now talking lipo) I bought some of these power packs to test:
http://panteltje.com/pub/high_power_lipos_IMG_5145.JPG
I still have to solder these in...
It is actually these:
http://www.ebay.com/itm/151808064280

I use similar batteries, mostly those used by the RC community.
http://www.hobbyking.com/hobbyking/store/__86__85__Batteries_Accessories-Li_Poly_All_brands_.html
This is my favorite 11.1v battery pack:
https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=26472
Yes, I pay extra for the shrink wrap, power connector, balance
charging connector, but don't want to build battery packs (until I get
spot welder).

Yes I have something like that from the local RC shop for my laser RC plane:
http://panteltje.com/pub/lipo_jump_starter_IMG_5105.JPG
used it to jump start my scooter

These ones have _no_ protection unlike the Varta marked ones, so BIG currents may flow.
So... 25 A discharge? Will see, will likely add a fuse.

The aformentioned favorite 11.1v battery is rated at 25C continuous
discharge:
25 * 2.2A = 55A
with a maximum charge rate of 5C or:
5 * 2.2A = 11A
You might as well use a PCB trace as a fuse. However, you can get
chargers with overcurrent protection:
http://www.ebay.com/itm/281843079093> 3S, 4-5A
http://www.ebay.com/itm/181749089393> 3S, 10-15A

Yes, well I meant the fuse for accidently shorting it.

 

[Spehro Pefhany]

On Sat, 21 Nov 2015 08:15:30 GMT, the renowned Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:

I get many things from China that look like 'home made',
for example the 1 Ah lipos with Varta on it, I am still not sure it really _is_ Varta,
but... 300 charge / discharge (90 %) cycles later I see a slight decrease in capacity.
reasonable for a lipo...

Possibly (probably) fake.

I replaced the Varta NiCd cells in a car instrument cluster a few
years ago- they lasted more than 20 years!


--sp






--
Best regards,
Spehro Pefhany
Amazon link for AoE 3rd Edition: http://tinyurl.com/ntrpwu8
Microchip link for 2015 Masters in Phoenix: http://tinyurl.com/l7g2k48

 

[Jeff Liebermann]

On Sat, 21 Nov 2015 19:45:17 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Sat, 21 Nov 2015 09:53:48 -0800) it happened Jeff Liebermann
jeffl@cruzio.com> wrote in <b4a15bdprkj42q39rkv10vvdhlsdp27a8d@4ax.com>:
At 90% discharge, you should be killing those batteries. At what
terminal voltage do you stop brutalizing those batteries? See Fig 2:
http://www.mdpi.com/1996-1073/7/9/5995/htm
10% would be about 3.50V.

Here's another way of doing it. Charge the battery to some voltage
below 4.2v and see how much capacity it has left:
<http://www.powerstream.com/lithium-ion-charge-voltage.htm>
Presumably, when it's done charging, the terminal voltage will equal
the charging voltage. At your 3.1v cutoff, the % of rated charge is
zero. 10% looks to be about 3.75V.

For LiFePO4 cells, 10% is about 3.25V.
<http://www.powerstream.com/lithium-phosphate-charge-voltage.htm>

Incidentally, notice how many charges he gets if you charges to
something less the 100% of capacity.

Eh, let's see, from asm source:
; Lipo battery cutoff voltage in mV
#define BATTERY_LOW_CUTOFF_VOLTAGE D'3100'

; Display will warn at this battery voltage level that battery needs charging
#define BATTERY_LOW_WARNING_VOLTAGE D'3200'

This is what I measured on the 'Varta' marked lipos:
http://panteltje.com/pub/lipo_discharge_curve_low_drop_out_regulator.gif

As I understand it, when the discharge curve hits the knee and starts
to drop off rapidly, it's time to stop charging.

>Now that you mention this I will try in a test-setup at a modest current (maybe 1 A) how long these new ones last.

Don't forget the battery terminal clamp.
<http://802.11junk.com/jeffl/LiPo/Ultrafire%2018650%20test.jpg>
I was getting really erratic results when I was using a battery holder
like this:
<http://802.11junk.com/jeffl/NiMH/cba-II.jpg>
Use the force.

>I like your big heatsink with fan battery test setup.

<http://www.westmountainradio.com/cba.php>
The heat sink and fan are necessary. I accidentally dumped some loose
junk over the fan, which then stopped. About 30 mins later, I smelled
smoke.

If you plan to build your own, please note that the CBA II has a
design defect in that it measures the battery voltage at the wrong end
of the test leads. At high currents, the voltage drop through the
leads and battery contacts can be substantial. I wanted to move the
sense wires from inside the device to the battery terminals, but never
finished.

For my test, I used 1.3A because that's what the flashlight I was
testing draws at maximum brightness. I would expect your counterfeit
cells to look very much like my counterfeit test battery:
<http://802.11junk.com/jeffl/LiPo/Ultrafire%20LiPo%203000%20ma-hr%2018650%20test.jpg>

>Yes, well I meant the fuse for accidently shorting it.

You might want to measure how long it will take your fuse to blow with
a partly discharged battery and a not so perfect short, such as a
screwdriver. A fully charged battery and a good short circuit will
blow most any fuse or fusible link. However, that's not always the
case when it shorts. I've had the fuse do nothing while the wiring
got hot enough to melt the insulation. Fusible links:
<http://www1.cooperbussmann.com/pdf/01e5795a-2857-422e-85c0-62eb8b13d2c5.pdf>




--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jan Panteltje]

On a sunny day (Sat, 21 Nov 2015 14:25:34 -0800) it happened Jeff Liebermann
<jeffl@cruzio.com> wrote in <vrp15b5vmsig704sj8p3481266nrjseqjr@4ax.com>:

On Sat, 21 Nov 2015 19:45:17 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Sat, 21 Nov 2015 09:53:48 -0800) it happened Jeff Liebermann
jeffl@cruzio.com> wrote in <b4a15bdprkj42q39rkv10vvdhlsdp27a8d@4ax.com>:
At 90% discharge, you should be killing those batteries. At what
terminal voltage do you stop brutalizing those batteries? See Fig 2:
http://www.mdpi.com/1996-1073/7/9/5995/htm
10% would be about 3.50V.

Here's another way of doing it. Charge the battery to some voltage
below 4.2v and see how much capacity it has left:
http://www.powerstream.com/lithium-ion-charge-voltage.htm
Presumably, when it's done charging, the terminal voltage will equal
the charging voltage. At your 3.1v cutoff, the % of rated charge is
zero. 10% looks to be about 3.75V.

For LiFePO4 cells, 10% is about 3.25V.
http://www.powerstream.com/lithium-phosphate-charge-voltage.htm

Incidentally, notice how many charges he gets if you charges to
something less the 100% of capacity.

I have only one lifepo4 cell so far, like this, but different seller):
http://www.ebay.com/itm/220983787601
it is in a keyboard, I only charged it once.. IIRC in May 2014, it is still working..

I do see prices are now coming down for lifepo4.

Eh, let's see, from asm source:
; Lipo battery cutoff voltage in mV
#define BATTERY_LOW_CUTOFF_VOLTAGE D'3100'

; Display will warn at this battery voltage level that battery needs charging
#define BATTERY_LOW_WARNING_VOLTAGE D'3200'

This is what I measured on the 'Varta' marked lipos:
http://panteltje.com/pub/lipo_discharge_curve_low_drop_out_regulator.gif

As I understand it, when the discharge curve hits the knee and starts
to drop off rapidly, it's time to stop charging.

Now that you mention this I will try in a test-setup at a modest current (maybe 1 A) how long these new ones last.

Don't forget the battery terminal clamp.
http://802.11junk.com/jeffl/LiPo/Ultrafire%2018650%20test.jpg
I was getting really erratic results when I was using a battery holder
like this:
http://802.11junk.com/jeffl/NiMH/cba-II.jpg
Use the force.

Right, and do not use Chinese Alligator test leads, the copper wire in those is so thin that at 100 mA it drops up to 2 V
for a 50 cm lead!
This has gotten me several times, finally keeping the alligator clips and soldering real wires on it.
Were not even soldered, just sort of pressed against the metal.

I like your big heatsink with fan battery test setup.

http://www.westmountainradio.com/cba.php
The heat sink and fan are necessary. I accidentally dumped some loose
junk over the fan, which then stopped. About 30 mins later, I smelled
smoke.

If you plan to build your own, please note that the CBA II has a
design defect in that it measures the battery voltage at the wrong end
of the test leads. At high currents, the voltage drop through the
leads and battery contacts can be substantial. I wanted to move the
sense wires from inside the device to the battery terminals, but never
finished.

Ehh I should have read ahead!

For my test, I used 1.3A because that's what the flashlight I was
testing draws at maximum brightness. I would expect your counterfeit
cells to look very much like my counterfeit test battery:
http://802.11junk.com/jeffl/LiPo/Ultrafire%20LiPo%203000%20ma-hr%2018650%20test.jpg

Yes, well I meant the fuse for accidently shorting it.

You might want to measure how long it will take your fuse to blow with
a partly discharged battery and a not so perfect short, such as a
screwdriver. A fully charged battery and a good short circuit will
blow most any fuse or fusible link. However, that's not always the
case when it shorts. I've had the fuse do nothing while the wiring
got hot enough to melt the insulation. Fusible links:
http://www1.cooperbussmann.com/pdf/01e5795a-2857-422e-85c0-62eb8b13d2c5.pdf

Or make your own electronic over current switch,
depends on how much you trust your own designs...

But I think to fuse a 25 A capable lipo battery with a 1 A fast fuse is OK for what I do.

 

[Allen Majewski]

On Friday, November 20, 2015 at 8:26:53 PM UTC-5, Cursitor Doom wrote:

Hi all,


I'm looking to acquire a new LCR meter to replace the old bridges I've
been formerly using, which can be a bit cumbersome. Can anyone recommend
one from personal experience? I've watched all sorts of 'tear down'
videos on YT but it's not clear if the people reviewing are involved in
some way with the manufacturers and therefore biased, hence I'd like to
hear from regular, independent users on their personal experience with
these devices.

thanks,

CD

Depends entirely on your needs. I use this one in the lab all the time, very good for up to 10 KHz http://www.zoro.com/bk-precision-deluxe-universal-lcr-meter-879b/i/G2322424/?gclid=COPrw8yhpskCFQ2OaQodEWUAng&gclsrc=aw.ds

 

[Joe Gwinn]

In article <ObY3y.120034$4M.92488@fx17.iad>, Clifford Heath
<no.spam@please.net> wrote:

On 21/11/15 12:41, Phil Hobbs wrote:
What frequency range?
AADE rf LCR

I have an AADE-type one that I built from a kit, pretty happy with it.

However, I still envy my friend's much more versatile and accurate
DE-5000. You can find those on EBay and Aliexpress stores.

I'll second that. I have one.

The DE-5000 was originally a General Radio design, and was most
recently made by IET Labs (who bought the wreckage of GR).

IET now sells a DE-6000, but there doesn't seem to be much difference
from the DE-5000 that it replaces in their product lineup.

Joe Gwinn

 

[mike]

On 11/25/2015 8:06 PM, dakupoto@gmail.com wrote:

Could some electronics guru please provide his/her opinion
on this supposed wireless cellphone charger circuit at the
following URL:

http://www.homemade-circuits.com/2015/09/wireless-cellphone-charger-circuit.html

What puzzles me is that how could an oscillator be set up with
just a 2N2222 BJT and a 220 Ohm resistor, without any information
on the inductances(antenna). I await your opinions.

it's a transformer

 

[piglet]

On 26/11/2015 04:57, mike wrote:

On 11/25/2015 8:06 PM, dakupoto@gmail.com wrote:
Could some electronics guru please provide his/her opinion
on this supposed wireless cellphone charger circuit at the
following URL:

http://www.homemade-circuits.com/2015/09/wireless-cellphone-charger-circuit.html


What puzzles me is that how could an oscillator be set up with
just a 2N2222 BJT and a 220 Ohm resistor, without any information
on the inductances(antenna). I await your opinions.

it's a transformer

Notice how the center-tap is connected to +ve supply. It is also a
Hartley oscillator (look it up if you want) tuned by the
self-capacitance of the spiral inductors and the reflected capacitance
of whatever receiver coil and attached circuitry is nearby. The
frequency of oscillation will vary as the whole setup is moved.

It creates electro-magnetic pollution and will seriously annoy anyone
nearby using AM BC or SW receivers.

piglet

 

[legg]

On Wed, 25 Nov 2015 20:06:28 -0800 (PST), dakupoto@gmail.com wrote:

Could some electronics guru please provide his/her opinion
on this supposed wireless cellphone charger circuit at the
following URL:

http://www.homemade-circuits.com/2015/09/wireless-cellphone-charger-circuit.html

What puzzles me is that how could an oscillator be set up with
just a 2N2222 BJT and a 220 Ohm resistor, without any information
on the inductances(antenna). I await your opinions.

Most respondents seem to be having issues (burnt switches), and the
blogger admits that he hasn't actually done it himself with the
described hardware. Oscillators operating on the principal of bipolar
transistor base current starvation will be inefficient, and are best
reserved for small-signal applications, where the losses are not
signifigant.

References in the blog are made to a you-tube video, which shows a
much larger heatsunk switch, and a maximum power transmission
efficiency of less than 50%, based on the actual DC load measurements
made there.

'Examining Wireless Power Transfer' TI SEM1200 topic3 slup321:

http://www.ti.com/lit/pdf/slup321

RL

 

[M Philbrook]

In article <425be2a7-0176-4d45-bc52-4eed84f9b2cd@googlegroups.com>,
dakupoto@gmail.com says...

Could some electronics guru please provide his/her opinion
on this supposed wireless cellphone charger circuit at the
following URL:

http://www.homemade-circuits.com/2015/09/wireless-cellphone-charger-circuit.html

What puzzles me is that how could an oscillator be set up with
just a 2N2222 BJT and a 220 Ohm resistor, without any information
on the inductances(antenna). I await your opinions.

its a dangerous circuit...

The 2222 is rated for 800mA last time I looked, and that should
be attached to a sink. Wattage is a factor.

There should be a regulator in there to supply the phone, I would not
be putting wild voltages to the phone.

Jamie

 

[legg]

On Fri, 27 Nov 2015 16:00:11 -0500, M Philbrook
<jamie_ka1lpa@charter.net> wrote:

In article <425be2a7-0176-4d45-bc52-4eed84f9b2cd@googlegroups.com>,
dakupoto@gmail.com says...

Could some electronics guru please provide his/her opinion
on this supposed wireless cellphone charger circuit at the
following URL:

http://www.homemade-circuits.com/2015/09/wireless-cellphone-charger-circuit.html

What puzzles me is that how could an oscillator be set up with
just a 2N2222 BJT and a 220 Ohm resistor, without any information
on the inductances(antenna). I await your opinions.

its a dangerous circuit...

The 2222 is rated for 800mA last time I looked, and that should
be attached to a sink. Wattage is a factor.

There should be a regulator in there to supply the phone, I would not
be putting wild voltages to the phone.

The phone's battery is a simple shunt regulator to the
impedance-limited source.

RL

 

[Tom Miller]

"legg" <legg@nospam.magma.ca> wrote in message
news:fhmh5bdgue0243gdsdh6i0jr8lqiudfd8l@4ax.com...

On Fri, 27 Nov 2015 16:00:11 -0500, M Philbrook
jamie_ka1lpa@charter.net> wrote:

In article <425be2a7-0176-4d45-bc52-4eed84f9b2cd@googlegroups.com>,
dakupoto@gmail.com says...

Could some electronics guru please provide his/her opinion
on this supposed wireless cellphone charger circuit at the
following URL:

http://www.homemade-circuits.com/2015/09/wireless-cellphone-charger-circuit.html

What puzzles me is that how could an oscillator be set up with
just a 2N2222 BJT and a 220 Ohm resistor, without any information
on the inductances(antenna). I await your opinions.

its a dangerous circuit...

The 2222 is rated for 800mA last time I looked, and that should
be attached to a sink. Wattage is a factor.

There should be a regulator in there to supply the phone, I would not
be putting wild voltages to the phone.


The phone's battery is a simple shunt regulator to the
impedance-limited source.

RL

Good luck getting it through Part 15 as an intentional radiator.

 

[M Philbrook]

In article <fhmh5bdgue0243gdsdh6i0jr8lqiudfd8l@4ax.com>,
legg@nospam.magma.ca says...

On Fri, 27 Nov 2015 16:00:11 -0500, M Philbrook
jamie_ka1lpa@charter.net> wrote:

In article <425be2a7-0176-4d45-bc52-4eed84f9b2cd@googlegroups.com>,
dakupoto@gmail.com says...

Could some electronics guru please provide his/her opinion
on this supposed wireless cellphone charger circuit at the
following URL:

http://www.homemade-circuits.com/2015/09/wireless-cellphone-charger-circuit.html

What puzzles me is that how could an oscillator be set up with
just a 2N2222 BJT and a 220 Ohm resistor, without any information
on the inductances(antenna). I await your opinions.

its a dangerous circuit...

The 2222 is rated for 800mA last time I looked, and that should
be attached to a sink. Wattage is a factor.

There should be a regulator in there to supply the phone, I would not
be putting wild voltages to the phone.


The phone's battery is a simple shunt regulator to the
impedance-limited source.

RL

Yeah? what about the circuits you need to go through before
getting to that battery?

Think.

Jamie

 

[Jeff Liebermann]

On Fri, 27 Nov 2015 18:27:56 -0500, "Tom Miller"
<tmiller11147@verizon.net> wrote:

The phone's battery is a simple shunt regulator to the
impedance-limited source.

RL

Good luck getting it through Part 15 as an intentional radiator.

I think you might mean "unintentional" radiator for external battery
chargers. See:
<http://www.ecfr.gov/cgi-bin/text-idx?SID=95ff763337f596a0ff6da3ef78b56380&node=se47.1.15_1101&rgn=div8>
Note that for a "Class B external switching power supplies", the tests
are only for "verification", which means the FCC trusts the
manufacturer to be honest, competent, and trustworthy. Right.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Tom Miller]

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:ad2i5bd70omef3idpnfs7u73sqr8spn4dg@4ax.com...

On Fri, 27 Nov 2015 18:27:56 -0500, "Tom Miller"
tmiller11147@verizon.net> wrote:

The phone's battery is a simple shunt regulator to the
impedance-limited source.

RL

Good luck getting it through Part 15 as an intentional radiator.

I think you might mean "unintentional" radiator for external battery
chargers. See:
http://www.ecfr.gov/cgi-bin/text-idx?SID=95ff763337f596a0ff6da3ef78b56380&node=se47.1.15_1101&rgn=div8
Note that for a "Class B external switching power supplies", the tests
are only for "verification", which means the FCC trusts the
manufacturer to be honest, competent, and trustworthy. Right.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

I think the external battery chargers referred to here are just line powered
switching supply bricks. It could be covered under "any other device"
though. But it does intentionally radiate a RF field. And it's anybody's
guess as to the frequency.

"honest, competent, and trustworthy" especially in China.

 

[Jeff Liebermann]

On Fri, 27 Nov 2015 21:27:17 -0500, "Tom Miller"
<tmiller11147@verizon.net> wrote:

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:ad2i5bd70omef3idpnfs7u73sqr8spn4dg@4ax.com...
On Fri, 27 Nov 2015 18:27:56 -0500, "Tom Miller"
tmiller11147@verizon.net> wrote:

The phone's battery is a simple shunt regulator to the
impedance-limited source.

RL

Good luck getting it through Part 15 as an intentional radiator.

I think you might mean "unintentional" radiator for external battery
chargers. See:
http://www.ecfr.gov/cgi-bin/text-idx?SID=95ff763337f596a0ff6da3ef78b56380&node=se47.1.15_1101&rgn=div8
Note that for a "Class B external switching power supplies", the tests
are only for "verification", which means the FCC trusts the
manufacturer to be honest, competent, and trustworthy. Right.

I think the external battery chargers referred to here are just line powered
switching supply bricks. It could be covered under "any other device"
though. But it does intentionally radiate a RF field. And it's anybody's
guess as to the frequency.

Intentional radiators are those that are intentionally designed to
communicate with some other device. Unintentional radiators are those
that belch RFI/EMI without a designated receiving device. I'm quite
sure that a switching power supply is not intended to send useful
voice, video, or data to a receiver, and is therefore an unintentional
radiator.

You'll find the definitions under:
<http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&SID=551cee4848a4b3cfb33ca2ec0292ef14&mc=true&n=pt47.1.15&r=PART&ty=HTML#se47.1.15_13>

(o) Intentional radiator. A device that intentionally generates and
emits radio frequency energy by radiation or induction.

(z) Unintentional radiator. A device that intentionally generates
radio frequency energy for use within the device, or that sends radio
frequency signals by conduction to associated equipment via connecting
wiring, but which is not intended to emit RF energy by radiation or
induction.

>"honest, competent, and trustworthy" especially in China.

Ummm.... I was trying to be diplomatic and subtle.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

On Wednesday, November 25, 2015 at 11:06:36 PM UTC-5, daku...@gmail.com wrote:

Could some electronics guru please provide his/her opinion
on this supposed wireless cellphone charger circuit at the
following URL:

http://www.homemade-circuits.com/2015/09/wireless-cellphone-charger-circuit.html

What puzzles me is that how could an oscillator be set up with
just a 2N2222 BJT and a 220 Ohm resistor, without any information
on the inductances(antenna). I await your opinions.

It's not an oscillator, it's a short circuit on the 12V source, limited only by transistor beta. The DC path through the transformer to the base locks the circuit up (with 60mA base drive which is a LOT), it will not oscillate. This type of circuit requires ac-coupled feedback to work.

 

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