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Rampart
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Not the way to determine ac diode impedance.Rampart said:<<In determining the diode dynamic resistance r,where did you get the 0.7V?The 4 mA?
The ac source gives maximum Vm=0.1V,so it is not possible to get 0.7 just from that.The main source is the dc source which gives steady 2V.But the AC source adds as well,does it not?
Yes.<<1. Determine the diode dynamic impedance r = ∂Id/∂Vd at the 2Vdc input level
of the diode when Vac in = 0. Use the standard I-V diode relationship for a junction diode>>
ok why i should take that AC source is 0? In order to use this equation dv/di=R, must i have only the DC source?
r is very nearly always constant and is computed when ac input = 0. r does not vary appreciably with ac voltage if ac current << dc current, here the case.Is it because R is a constant only when the as source is 0? Only when there is a linear relation? Do i get from the graph that AC must not be taken into account? I am just posting some thoughts i have into mind...
That is basically right. Your ac amplitude is << dc voltage at the diode anode so r is always constant.>
2. Then it's a linear problem if you neglect the small changes in r with input ac voltage. The dc diode current and dynaminc impedance do not change significantly with ac input voltage (why?). The diode ac current is determined by r and the 100 ohm resistors.
I take that AC source is 0, because its voltage is too low so that it doesn't really make any difference? That is why in the graph there is a linear relation between id and vd?
I believe the problem wants you to find iac and Idc. iac is determined by including r in your equations, along with the two 100 ohm resistors. Idc is determined by a dc analysis with the input ac voltage = 0. These are basically totally different computations.And now the thing i do not have a clue about.<<The diode ac current is determined by r and the 100 ohm resistors>>.If i regarded AC source is 0, why should i find the ac current? Wouldnt it be
id=idc+iac ~ idc(where idc is the current that is <<produced>> only by the dc source).
Only very slightly. You are to ignore that variation. The reason is that the ac amplitude is << dc input voltage.Do Id and Vd change through time just because of the ac source?
You're welcome!Rampart said:You sir,honestly speaking,made my day.Some things are more clear now and i thank you for that!
A diode is an electronic component that allows electric current to flow in only one direction. It is made up of a semiconductor material and has two terminals: an anode, which is positively charged, and a cathode, which is negatively charged.
A diode works by using a built-in electric field to allow current to flow from the anode to the cathode, but not in the reverse direction. This is due to the difference in energy levels between the two terminals, which creates a barrier for current flow in one direction.
A dc (direct current) voltage source provides a constant and steady flow of electric current in one direction, while an ac (alternating current) voltage source periodically changes direction. This results in a fluctuating current flow.
Yes, a diode can be used as a dc voltage source by connecting it in series with a resistor and a power supply. The diode will act as a one-way valve, allowing current to flow in only one direction, while the resistor will limit the amount of current that can flow through it.
To measure the voltage of a dc or ac voltage source, a voltmeter can be used. The voltmeter is connected in parallel to the voltage source, and it will display the voltage reading in either direct current (DC) or alternating current (AC) depending on the type of source.