This type of negative resistance is said to be "voltage stable" or as well N-type because I vs U curve a little resembles letter N. It's voltage stable because certain applied voltage causes certain predictable current.
But if we knew the current the voltage could be any of three possible values depending on how the current is fed.
R6 is in principle unnecessary, but it's very useful if you try this circuit. It prevents Q3 to burn. Diacs, thyristors, UJTs and many gas discharge or avalanche based devices work differently. They have a mechanism which makes more current as the current has reached a certain limit.
For example in thin gas thermal collisions and voltage together cause ionization. Ions move due the voltage and cause more ionization due the increased collisions. The said principle "Current makes more current when the current is high enough" can be easily built into a simple transistor circuit.
The source in the right is adjustable current source. Feeding with voltage source cannot show the operation properly because the negative resistance is "current stable". As the collector current of Q1 increases at some point the voltage over R3 reaches 0, That makes Q2 conductive and increases the base current of Q1 which causes more Ic and finally more base current to Q1.
If we increase V Node1 gradually upwards from zero we see how the current suddenly jumps upwards. This is actually a flip-flop which flips its state at certain voltage. As said this is "current stable". By feeding with current source we can reach all possible current values. Here's a current sweep from 0 to 20 mA:. The critical current which would in with voltage fed system make more current is 5,5 mA which needs voltage about 4,2V If we increased the voltage just over 4,2V the current would jump much higher, actually to about 40 mA.
That's what can go through R3 with 4V, the transistor needs about mV Vce. If we change the V axis horizontal and I axis vertical in the graph the pattern resembles a lille letter Z. That's another name for this negative resistance type.
That's not true. You cannot use a thyristor as a voltage source - something is red or understood wrongly. But a circuit which has negative resistance can output energy which is of course taken from ordinary power supply in practical circuits.
We have microwave amplifiers and oscillators based on negative resistance. In lower frequencies ordinary amps are more effective, but in theory nothing prevents us to build a low frequency negative resistance amplifier.
If you only play with equations you can easily put a negative resistor to charge a battery. Simply connect them together. In a simple way, resistance is the ratio between voltage and current, if you plot the voltage versus the current present in a certain component, the resistance will appear as the slope between these variables. In a physic way, a positive resistance means that if the voltage of a component rises, the current that flows by also rises, otherwise, a negative resistance means that when the voltage of a component rises, the current declines.
DC-DC Converter inputs are a good example of a negative resistance. As voltage goes down, current increases to provide the same power output. Also a negative resistance can be created by an op amp circuit. Sign up to join this community.
The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. What is the physical meaning of negative resistance? Ask Question. Asked 2 years, 6 months ago. Active 11 months ago. Viewed 5k times.
Circuit fantasist 8, 1 1 gold badge 13 13 silver badges 34 34 bronze badges. Kinka-Byo Kinka-Byo 3, 2 2 gold badges 9 9 silver badges 26 26 bronze badges. If you have such a device, take care not to short it out with a zero ohm resistor. I cannot compute the power dissipated in such a circuit.
Show 2 more comments. Active Oldest Votes. See also: Demystifying the Negative Differential Resistance Phenomenon Absolute negative resistance is done in a more natural way - by a dynamic voltage source electronic circuit. See also: Investigating the Linear Mode of Negative Impedance Converters with Voltage Inversion So, the "physical meaning of negative resistance" is "dynamic resistor" or "dynamic source". If the input source tries to increase the current, the voltage drop across the positive resistor increases and it should affect the current.
But the negative resistor vigorously decreases its resistance to reduce the voltage drop across itself by the same value. The total voltage across the whole network R and -R in series does not change; it behaves like a Zener diode with zero differential resistance. So the differential negative resistor compensates the change of the voltage drop across the positive resistor Absolute negative resistance.
It compensates the absolute voltage drop across the positive resistor not only the change by inserting the same voltage. For this purpose, it uses an additional voltage source with opposite polarity.
The total voltage across the whole network is not only constant but zero. The network really behaves as a "piece of wire" and does not impede the current. Popular examples of this arrangement are the transimpedance amplifier and inverting amplifier in which the op-amp output acts as an absolute negative "resistor". It destroys the feedback resistance by compensating the voltage drop across it with equal voltage. It is likely the related discussion in ResearchGate will be of interest to you: And why are there two more types of negative resistance?
Circuit fantasist Circuit fantasist 8, 1 1 gold badge 13 13 silver badges 34 34 bronze badges. Add a comment. If you want to play with a negative resistance effect, one way assuming you don't mind one end being grounded is to use a negative impedance converter : simulate this circuit — Schematic created using CircuitLab The above circuit acts like a K resistor with one end grounded within its linear range , and works down to about zero volts.
The relationship between internal resistance denoted by r and emf denoted by e of a cell is given by that are:. On rearranging the above equation we get the following:. In the above equation, we can say that the letter V is the potential difference terminal across the cell when the current which is denoted by I is flowing through the circuit.
We can note: The emf denoted by letter e of a cell is always greater than the potential difference generally terminal across the cell. Example: 1 that is the potential difference which is across the cell when no current flows through the circuit that is 3 V. Determine the internal resistance denoted by letter r of the cell?
Now due to the Internal Resistance which is of the cell that is the electrons moving through the cell which turns some of the electrical energy to heat energy. Therefore we see that the potential difference is available to the rest of the circuit that is:. The electromotive force that is denoted by e or the e. So we can say that it is measured in volts that is V. It is said to be equal to the potential difference which is across the terminals of the cell when no current is flowing.
When the flow of electricity is around a circuit the internal resistance that is of the cell itself resists the flow of current and so thermal that is said to be heat that is the energy is wasted in the cell itself.
Here the rearrange of the the above equation is:. This is called the open circuit potential of the circuit. Because there is no current there will be no lost volts so this value is the EMF of the cell. So the point where the line meets the terminal potential difference axis, the y-axis intercept is the EMF of the cell. At the point where the line meets the current axis, the x-axis intercept the maximum current is drawn from the cell. This would be achieved by short circuiting the cell this should be avoided as the cell could overheat and it is potentially dangerous.
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