Recent content by cabraham

If the secondary is unloaded, the impedance is infinite in the ideal case, so that a secondary voltage & zero current occur. In real world transformers, the secondary winding has a capacitance. This capacitance charges & discharges every ac half cycle. The secondary current is not zero, due to...

No! I am saying that cause & effect cannot be determined from this equation. I attached simulation showing I-V response to a staircase generator function. The plot waveform gives insight into which quantity changes first, & which responds to said change later.

BJT is ultimately charge controlled. The following terminal equations are used to describe bjt: Ic = beta*Ib Ic = Ies *exp ((Vbe/Vt) - 1) Ic = alpha * Ie A good simulation program or lab tests will affirm that changes in current happen before change in voltage. A p-n junction has some...

Inductor cannot "create an emf". It has no internal source of chemical reaction like batteries do, nor any moving parts to generate. When a circuit with an inductor is closed, the current is made up of charges moving in the conduction band, the highest energy level. When the switch opens, the...

Here it is. The *reverse saturation current*, "Is", is the reverse current of the base-emitter junction. This is denoted as "Is" in a diode, a 2 terminal device. But a bjt has 3 terminals, & 2 p-n junctions. The collector base jcn is reverse biased when bjt is biased in its active region...

Thanks for examining my plots. Of course the trace align at the edge of window, we agree on that. But notice that Vne rises, eventually settling. But the currents, Ib/Ie/Ic rise faster, overshoot very slightly, then decrease, settling to final value. Ic responds to Ie rising by rising, Ie...

This attached pdf demonstrated the relation between Ie, Ib, Ic, & Vbe. The Vbe lags behind Ib, Ie, as well as Ic. Vbe cannot be the controlling quantity.

Fair question re where does alpha come from. Here is a fair answer. Alpha is Ic/Ie. When the b-e junction is forward biased, Ib & Ie are nonzero, as well as Vbe. It is desirable to make Ic as close to Ie as possible, minimizing Ib. Alpha = beta/(1+beta). Infinite beta means alpha = 1, & Ib = 0...

I realize SE (Shockley equation) is NOT an axiom. In semiconductor physics class,cwe derived it as homework. It is not a solution to bjt, but solution to diode. The SE describes the math relation between diode voltage & current in forward direction, or to limited extent in reverse before Zener...

Ic is NOT "determined" by Vbe. Ic changes as a result of Ie changing. Vbe catches up eventually. Many references, including uni texts, often use the Shockley equation Ic = alpha*Ies*exp((Vbe/Vt)-1) as "proof" that currents Ie or Ic are "controlled" or determined by Vbe. But Shockley's equation...

Vbe does NOT "modulate height of barrier". Also how can diffusion "move the charges"? Diffusion is the tendency for charges to spread out until all regions have equal concentration. The barrier in a bjt without being energized is the thermal voltage, roughly 25.9 mV, usually rounded off to 26...

But the "driving E field" is your assumption. How does a battery produce an E filed & voltage. The chemical process, redox, propels positive ions towards positive terminal, & negative ions towards neg terminal. In this case, this current moves against the E field & increases it. Inside the...

Electric force does that. Singer Sue outputs acoustic energy that mic transduces into E field. This sets charges in motion. Charges move through mic cable & reach bjt b-e junction. Ib, Vbe, & Ie get changed from these new charges showing up. Any elaboration still needed.

And how are E fields set up inside conducting material? By transporting charges, of course. If Sue stays silent, how can the bjt have E fields created inside its b-e region? E fields are the result of the external mic, after being energized by Sue's vocal energy. Charges are transported the...

The signal generator. Could be an antenna, phone cartridge, microphone, etc. For example, Sue sings into a mic, charges are moved by her vocal energy. If mic is dynamic, her air pressure from her voice moves the mic diaphragm & charges are moved. This wave travels through the mic cable & reaches...