Yes ! One more non-linear element in SimOhm ! SimOhm has recently launched a new non-linear element named diode, familiar with most of you, at least electrical engineers or physicists. However this diode will make you able to create more advanced circuits, and view their transient response.
Before going into technical details, lets state some important things a diode can do. Do you know that your laptop or mobile charger works on direct current (DC), which means that we have a stable constant current of zero frequency. But the power provided from the electrical grid in our countries provide alternating current (AC) only, so how to change this alternating current to a dc current? In that case we will need a rectifier. A rectifier is a name given to a big box, which can be found in every single building in the power or telephone room place in that building. This rectifier has a rectifier circuit. This circuit as shown in the simulation below has an alternating source, a diode and a resistor connected in series. This diode has the property of making current flow in one direction only. The diode has two junctions (ends), cathode (the n-doped layer which has the negative charge -electrons-) and anode (the p-doped layer which has the positive charge -antimatter or protons-). In a circuit current flows from positive to negative, so this means that current in a semiconductor flows from the negative to positive (from n to p) and can never move from positive to negative, and this property makes the diode a unique electronic semiconductor component which makes current flow in one direction only. This gives rise to many applications where a diode can be used in, such as the conversion from alternating to direct current explained above. The diode is also used in envelope detection circuits which are used in amplitude modulation (AM) in radio communication systems and several other applications. Diode as also used in npn or pnp BJT or MOSFET type transistors, which are used as electronic switches and they also have a wide scope of applications which might be explained later in another post.
Now lets see how can we play in this device and create several applications. As stated above, the diode can be used in rectifier circuits. But in simulations, we just state several assumptions, and model our system using accurate parameters. To create a diode in SimOhm, every diode has a threshold voltage. This voltage changes with the temperature surrounding the diode. An increase in temperature, increases the voltage across the diode and viceversa. Coming back to threshold voltage, this voltage is the minimum voltage required for a diode to operate. You can vary the threshold voltage but for our modeled diode, we have a threshold voltage of 0.01V. In addition, you can vary the diode forward and reverse resistances (forward resistant is the resistance a diode should have when the voltage is above the threshold voltage -and this should be as small as possible o.1-; whereas, reverse resistance is the resistance a diode should have when it the voltage across it is less than the threshold voltage -and this should be as maximum as possible, infinity-).
Play the simulation and see how the alternating voltage operating in the positive and negative region gets to operate only in the positive region, by taking the output voltage on the capacitor (note that in practice, conversion from AC to DC requires a rectifier and a stabilizer circuit in order to have a constant output voltage):
Increase the simulation speed for faster results.
And below is a clipper circuit:
Confident enough?
Now go ahead and create design your own simulation @ http://www.siminsights.com
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