Comment by wbeaty on Was Benjamin Franklin wrong (about conventional current)?
> In the kinds of experiments Franklin did... You mean the Kite experiment, where Franklin used twine as the main conductor? Twine, if slightly humid, and if slightly acidic like paper, is a...
View ArticleComment by wbeaty on Was Benjamin Franklin wrong (about conventional current)?
If that happened, it would be up to the physicists, and we all know that, out in nature, metal nuggets are rare. The most common currents are electrolytic, with pos and neg both flowing in opposite...
View ArticleComment by wbeaty on Since electrons travel from negative pole, do signals...
> I simply wonder if there is a trend for a signal to arrive first to components closer either pole. -- It might help us if you would explain why you would ask this question? What thinking led to...
View ArticleComment by wbeaty on Photovoltaic generated power: Why is my PV system...
Well, what's that 0.8KWh spike that happens daily afternoons? If you knew what it was, then you'd know how long it actually lasts (must to be lots less than a full hour.)
View ArticleComment by wbeaty on If any "antenna" can be impedance matched to the source,...
Matching can cause AE aperature to increase (that's how "chip antennas" in your phone can be 5mm wide.) An electrically-small antenna is lousy because it's made from real-world lossy materials, and...
View ArticleComment by wbeaty on Why doesn't voltage on one terminal of a capacitor matter?
Note that this applies to AC only. The DC power supply is a short circuit for AC.
View ArticleComment by wbeaty on Why doesn't voltage on one terminal of a capacitor matter?
@EE18 the for-dummies explanation: all this only applies to AC. And for AC, the power supply is a short circuit (or at worst a fraction of an ohm.) For AC, Vdd is laready connected to ground. The "huge...
View ArticleComment by wbeaty on Weird DC motor behaviour at low PWM duty cycle
@Solmyr999 mosfets can unexpectedly oscillate at MHz, and fry themselves. To stop this, the gate resistor must be placed at the mosfet gate, and not at the 555 pin. 100ohm or 1K is typical, giving RC...
View ArticleComment by wbeaty on Isn't current flow a wrong term?
IIRC this was in '80s edition... "Since a current is a flow of charge, the common expression 'flow of current' should be avoided, since literally it means 'flow of flow of charge.' - MODERN COLLEGE...
View ArticleComment by wbeaty on Electroconductive fabric
quick googling also turns up the term "surfacing veil"
View ArticleComment by wbeaty on Current in BJT at EBJ and its mechanism about Diffusion...
@LvW Win Hill, the AOA author, says he was taught "current gain" in college, and it screwed him up! In first design job, a wise old engineer had to take him aside and debunk that stuff, instead showing...
View ArticleComment by wbeaty on Uncertainty of transistor hfe/beta values
Note that this involves the "for dummies" explanation where BJT transistors are current-amplifiers and not transconductance elements. Analog designers know better. "Art of Electronics" AOE is the...
View ArticleAnswer by wbeaty for Why does electricity require a closed loop to flow?
.Shouldn't electricity flow? I know it doesn't but I don't understand why.It did flow.A very brief current appeared as you connected the terminal to ground, and again when the battery restored its...
View ArticleAnswer by wbeaty for Amplifying 40ns pulses that come at unknown times (for...
Building an APD interface box? Avoiding going online to buy one (where's the fun in that. Might be a few hundred bucks though. Heh, even less fun!)How is this normally done? I recently had a dead APD...
View ArticleClik here to view.
Answer by wbeaty for How does an inductor store energy?
Visualizing b-fields and inductors? Like this video?https://youtu.be/1elpVmpkBH4Go find professor J. Belcher's videos from MIT e&m course "TEAL project," with EM animated visualizations. Every coil...
View ArticleAnswer by wbeaty for What happens if a small Tesla coil is fed with a...
The key to understanding is: think about constant-voltage power supplies, where the load determines the current, which can be anything from zero to I(max.) A very large AC line-transformer will happily...
View ArticleAnswer by wbeaty for If Conventional Current is wrong, how can I trace the...
if Conventional current is wrongConventional current: used by engineers and physicists everywhere. It's what's measured by ammeters! It applies to all circuits, including the non-electron flows in...
View ArticleAnswer by wbeaty for Is a dedicated bandpass filter chip really neccessary...
It's not just a bandpass filter. It's an antenna tuner, a "transmatch" or Z-match block, which performs the same task as a transformer. (But a resonant transformer, in this case.) It steps...
View ArticleAnswer by wbeaty for Silicon Diode Threshold Voltage 0.7
A slightly-more ELI5 answer:When we touch any two different metals together, they charge up, one becoming positive, the other negative. They form a self-charging capacitor, or something like a...
View ArticleAnswer by wbeaty for What is the DC analysis of shorting both ends of a diode?
A JUNCTION-POTENTIAL forms at the wire connections to the diode's silicon surface. Not a depletion region, not a new diode. It's called a "non-rectifying junction" (google search.) Also see "Ohmic...
View ArticleAnswer by wbeaty for Disadvantages of charging Li-Ion battery indefinitely?
A million swelled-up Samsung Galaxy tablets and phones!Don't continuously charge flat-wafer type Li-ion batteries found in phones and tablets.If left continuously hooked to the charger, these wide,...
View ArticleAnswer by wbeaty for Distribution of surface charges along the wire
The question really could be written so: when we instantly apply a potential-difference to the ends of a resistor, how does the resistor respond over time, in order to eventually exhibit a constant...
View ArticleAnswer by wbeaty for How does a receiving antenna generate current/voltage?
Usually the intuitive, non-math explanation of receiving antennas is avoided in introductory texts. Instead, they steer around the problem by only explaining transmitters and the emission of EM waves....
View ArticleAnswer by wbeaty for Can I amplify and listen to the RF frequencies in my body?
Body as antenna? Or are you after the signals originating in your body?For the latter, you'll be finding muscle signals, heartbeat, and brain-waves. EMG, EKG, and EEG. Your amplifier gain is minimal,...
View ArticleClik here to view.
Answer by wbeaty for What is the physical model for energy flow in or around...
Electroboom gets it right (new posting.)https://www.youtube.com/watch?v=iph500cPK28This is non-controversial, utterly simple RF design knowledge ...when it's only occurring over a fraction of a...
View ArticleClik here to view.
Answer by wbeaty for How does an antenna radiate (how do currents flow...
Here's an oversimplified version that helped me get past my own noob ignorance.There are basically two types of small antennas: the small loop antenna, and the short dipole antenna. The small loop...
View ArticleAnswer by wbeaty for "Ground" vs. "Earth" vs. common vs. negative terminal
Problems:First, currents don't "come from" the positive terminal. That's a very common misconception, an error called the "sequential fallacy" appearing widely in grade-school electricity textbooks....
View ArticleAnswer by wbeaty for Listening to electromagnetic fields
It's not really worth it unless it's portable. You want to carry it all around your house, or walk around your neighborhood.Wave the pickup-coil around a desktop PC or oldschool laptop. Walk under...
View ArticleAnswer by wbeaty for Can unpowered radio work without ground connection?
I recall that early crystal radios sometimes used wide loop antennas (like a hula hoop, or a several-feet square diamond, or octagon. Or basket-weave coils many inches in diameter.) Look up: crystal...
View ArticleAnswer by wbeaty for Why can't current change instantaneously in a given...
Another simplistic explanation, but energy-based...With capacitors and coils, to make changes, we'd have to remove some EM energy from, or add some EM energy to, each component.In wires, what is the...
View ArticleClik here to view.
Answer by wbeaty for In a basic Ohm's Law circuit, is the effect of the...
Ah, you've hit the grade-school misconception that "current" flows in wires ...and that wires are like hollow pipes. The power-supply must fill the pipes ...so how can it possibly know about the...
View ArticleAnswer by wbeaty for I am struggling to use and really understand...
At first, build some simple and fun projects that always work. It doesn't have to be "useful," instead it must be something YOU want to build. Your goal is to have a functioning circuit which does...
View ArticleClik here to view.
Answer by wbeaty for How can energy "physically" be fed back into the grid?
Ah, the apparent paradox of energy. Don't forget, electricity goes equally back and forth. It's an AC system after all.How then could we ever feed any electricity to any homes? Answer: we don't have...
View ArticleAnswer by wbeaty for Energy Transport in Circuits
In many ways the incorrect "coal cars" or "energy buckets" explanation is less problematical. If you're not planning on a science/engineering career, then the "lies to children" will make things far...
View ArticleAnswer by wbeaty for How to stabilize a Comparator op amp from static currents?
Are you certain that L1 and L2 are grounded to your supply common? Use an ohmmeter to make sure that you see zero ohms to gnd/common, when measured at the other side of the 10K resistor connected to...
View ArticleAnswer by wbeaty for Electric field near dynamic loudspeaker at resonant...
The metal case should give you lots of shielding. And the e-field should all be coming from the solder terminals and the coil-wires on the cone.Since this doesn't appear to be the case, then probably...
View ArticleClik here to view.
Answer by wbeaty for Voltaic pile: question on components
Meters were invented two decades later (Oerstead's compass.)So, how did Volta discover that something was going on here? Wet fingers! With hands well soaked in water (or seawater, or vinegar,) touching...
View ArticleClik here to view.
Answer by wbeaty for How can there even be an input voltage on a long-tailed...
This is a classic misconception: "VBE is constant, BJT transistors are current-controlled devices." Nope, wrong.So, your #1 above is wrong. Long-tailed pairs are based on changes to VBE. The VBE...
View ArticleAnswer by wbeaty for My scope detects a 50Hz signal when the probe is not...
Yes it's normal.You're seeing a capacitive divider effect. One capacitor is within the scope-probe and essentially is connected between the probe-tip to the scope ground. The other, much smaller...
View ArticleAnswer by wbeaty for 2 phase to 3 phase
Use only one of your phases. First actually measure your outlet's AC volts between prongs.A 3-phase outlet will be ~208VAC on a single phase, for roughly 90% heating on a heater designed for 220VAC.If...
View ArticleAnswer by wbeaty for How would I test the continuity of an anti-static wrist...
The built-in resistor might be well above 10M ohms, and a cheap DMM meter would see this as an open circuit. (But many wrist bands use 1M resistors, easily measured.)Wrist straps are not supposed to...
View Article
