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683 Threads found on Current Source Circuit
Leastwise, all current mirror components will appear as noise sources in your equivalent circuit.
Without knowing the EMI immunity of the layout, you must consider the breakdown voltages for each terminal to protect it from excess reverse voltage One diode could be used for this purpose especially with inductive lines and open circuit with current. Keep the current loop small in area with coax or twisted pair and you may still need a CM (...)
(1) It's a trick to calculate the Thevenin resistance. Feeding the circuit with an auxiliary source, find the current and then makes R_{th} = \frac{V_{aux}}{I} But solving the circuit in that way is the worst idea that a human can have. Note: I_l + I_s = I_l + \frac{V_l}{2} = \frac{3 I_l - V_l}{4} \;\;\long
Your circuit may work but there are several problems with it. First the third gate output should not be directly connected to transistor bases but via a current-limiting resistor. Second, MOSFET gate should be protected from an overvoltage, typical maximum gate-source voltage is 6V. Third, with the inductive load the MO
Hiii all, For constant current source circuit,can I use any type of op-amp? or in other words all op-amp will support constant current application? In my project I want to give constant current of 1.5mA to a pressure sensor. Thanks in advance.
try lower Rds on mosfets with lower gate charge, try a 45% duty cycle, try increasing the resonant freq of the ckt so the mosfet turns off as the current rings down to 20% of peak...
Can anybody explain the output current and voltage waveforms for the bridge rectifier circuit?I could not find it anywhere.....I have attached the circuit
Very confused question. What does "if I use a DAQ board which has a digital pin output from 0 to 5V, for this application, can it source the current & provide the negative voltage necessary for my circuit?" even mean? First of all, yes a power supply can supply negative voltage if the (+) and (-) terminals are isolated from ground. Like (...)
I was thinking something like this for adding the modulation current: 113699 Will the switch cause spikes in the pulses? What Voltage controlled current source do you propose? Does some one has simulation model for laser diode? plz help
i tried to implement a multilevel inverter. i done already in matlab which shows what i want. during the hardware implementation the output voltage shows the same result as in matlab if load is zero. when i connect a load the output voltage becomes zero no current flows through it.why this problem occurs. the sources are 3 nos of 12V battery whic
Dear all, I am using cadence to simulate input referred current noise of opamp. However, i have no idea about how to build the test circuit, since i cannot use a current source and define it as an input current source in noise analysis. Can anyone help? Thanks a lot!
The equation Ve=... is not correct. This equation assumes that Ve is determined by Vx only - and you forgot the current source.
Friends, I would like to design a class E power amplifier. As you know, voltage and current waves of the switch in negative peak must be zero, but in my circuit they have negative values. When voltage is negative, current is positive!So, in this condition the switch can work as a source of power and can produce power!!! (...)
Sink versus source is only a different (more graphical) way to describe current polarity. Asking generally about "sink and source" current doesn't make much sense. The input or output current of device depends both on the external circuit and the internal function. A datasheet (...)
Hi, I'm using some chipset via USB which allows an input voltage between 4 - 20V In order to block 12V from injecting to the 5V power circuit I'm using a diode on the 5V supply. While this works fine with 12V (since the current is low), when I power the chipset with 5V the current is quite high which results that this diode is heating (...)
Would you mind to explain the purpose of the opto triacs in the shown circuit topology? Besides other problems, their current rating doesn't seem to fit the MOSFETs. The schematic is somehow incomplete, it's not shown how the gate signals are generated and if they are referenced to the MOSFET source terminals as required. If so, there's (...)
hi, how can I make a circuit with positive and negative voltage with high current. With such skimpy info, an informed suggestion cannot be made. How much is "high current" and how much voltage? Do either need to be adjustable? Does it need to be regulated? What is the power source?
Hi all! Do any of you know of any buck, boost or buck-boost constant current circuit that is able to regulate current more than 2A? Thanks!
Hi, I assume that the AC is mains frequency current? If yes, there are many possibilities. One is a current transformer, which gives total isolation of the measuring circuit from the monitored current. It is easy to implement. I have seen, that there are even cheap small current transformers available in (...)
Is the bottom symbol a current source? If it sees high impedance at any time, then it will try to overcome it by generating a high voltage.
The most popular methods are to use a switched current source alternating from,sink to source at safe levels and looking at the response time for excessive capacitance which can signal an "almost short "in CMOS or a low voltage swing. Backdriving junction points incircuit are often done by ATE but this won't detect (...)
The transistors in such a circuit have to be complementary for proper operation. So the input transistors are typically NMOS and the load is typically PMOS. But it could be done with the input transistors PMOS and the load NMOS. Basically the drains of the two transistors have to be facing each other for the circuit to work since you need
Thank you so much BigBoss could you tell me where it comes from( Gm=Idss/abs(Vp) )? and how can we find the source-Drain current with specific gate-source voltage or vise versa ? It's not coming from somewhere, I have given a rough expression for that.There isn't a handy consistant equation for HEMT devices therefore
1. The third OP is acting as a comparator (the integral of a triangle would be hardly a square wave, by the way). 2. It's a voltage rather than a current source. 3. The first OP forms a schmitt-trigger. The overall feedback is negative, the combination with the schmitt-trigger makes an astable oscillator.
pls explain me the working of this circuit.The text says that current source Q1 functions as usual but with collector volt- age held fixed by Q2's emitter...i.e the collector voltage of Q1 is held fixed by action of transistor Q2.But what i didnt digest is that if the temparature changes then the Vbe of Q2 changes resulting in a change of (...)
A PV is essentially a lossy current source that has a zener like open circuit voltage, Voc that declines slightly with lower solar input. The maximum power point is approximately 80+/-5% of Voc when the VI product has a shallow peak in power about this centre. You can hunt for this peak using MPPT regulated current sinking (...)
Hi, I don't know what you mean... To drive a LEDfrom a voltage source you need a current limiting resistor. Because the bias voltage is high in relation to a LED forward voltage the output (light) will be about proportional to input voltage. Klaus
In a RC circuit, if the voltage source is a sinusoidal source, I found the given equation. C is constant. I tried to solve this problem in time domain. So, I use a source in an EDA tool. I found the current in time. I know the voltage. I use simple numerical derivaton df(x)=/(x2-x1). In this case, derivatio
If you assume that the current source has an internal energy source (an ideal current source in a simulation of course has), you don't need Vdd. A technical current source, e.g. a transistor circuit will need an external energy source. - - (...)
This would be the final circuit. 115848 But I do not know what value must be R2. Because I do not know what value would have Ic2 (Q2). R2 is totally unnecessary. With the shown value it would just reduce your constant current to ≈75mA. And
Let the voltage across Rx = Vx and battery current , I. Then V1 = (4k7/4k7+2k) X Vx, re arranging gives Vx = V1/(4k7/6k7). So 3.3 V = (100 X I) +VX, { 100 X I = volt drop across 100R ), rearranging, (3.3 - Vx) = 100 X I, so I = (3.3-Vx)/100. So I is the current from the battery, some flows through the 1K (Vx/1K), some flows through the output
Hi All, if I want to play with the PSR of a circuit block(for exmaple, op-amp), an AC signal is injected into VCC, and I want to use an ideal ac gain block to amplifier this AC signal and convert it to a current source. Would anyone teach me what is the easiest way, to implement Vin(ac) to Iout(ac)? Thank you! 114937
You can put some back-up capacitors to increase the circuit working time out of external energy source. With the battery, supply a low power comparator (its current consumption actually depends of your need) with a battery supplied reference, say 3V, being the compared voltage one generated by the external power supply. The comparator will (...)
Transistor current in flyback is unipolar sawtooth waveform. Where do you see current through body diode?
You should first tey and find the threat source or info about it (if this is a field return). Then, what you mean by "burned out" along with what you know about the event, may lead you somewhere. Those zeners / TVSes have peak current and short term average current and short/medium term power limits. An ESD event of classical form (...)
I think the input reference current changes the oscillator frequency.
If you just want to shut-down Vout -> 0V , it's enough to connect the power transistor's gate with its source - by a transistor switched via the enable/shut-down pin. Should you need a total 0-current shut down, you'll have to disable some control current, plus, possibly, inactivate some extra enable transistors. For more detailed info (...)
Other than Vref, this design has no input and the current sense has open loop gain so it doesn't matter what Vref does. What is the point?
In the circuit you have an independent current source (the left-most), a current source that generate a current of ampliteude depending from the current flowing in the 2 ohm resistor and two resistors in parallel. You need to apply Ohm's law, but also Kirchoff's law. The (...)
Almost all Mosfets are power Mosfets. You forgot to tell us the maximum current that you want in your Mosfet. Most Mosfets need a gate-source voltage of 10V to fully turn on (but 'logic-level" Mosfets need only 5V) so you need a gate driver circuit to boost the 3.3V from your microcontroller. The gate pulses to the Mosfet must be much higher (...)
Hello, Can anyone suggest a simple current reference circuit for a two stage op amp. I need to generate constant current in uA range to be injected in the diode connected transistor and mirrored at both the stages. Thanks, Hobbyiclearner
Left circuit is well known Widlar current mirror.. Right circuit is a voltage controlled current mirror/source..
AC has to be scaled and shifted and then measured. DC has to be scaled and measured. Same for current.
It's a simple cross-coupled LC Oscillator with Noise Filtering (by order to simulate such circuits, a start-up simulation trick should be used to excite the oscillator. For instance a step-up current may be injected into the circuit during a limited period or a step-up voltage source can be used to excite the (...)
To get a DC current as high as 1A and using a frequency of 200kHz then the coils will probably be fairly large and/or have a ferrite core. Since the coils probably must touch together then why not use a plug and jack?
For a LED driver you need constant current, not constant voltage. This is because the LED forward voltage drop changes with temperature, if driven from a truly stabilized voltage source would cause large changes of current through the LED. The total voltage drop might be around 30V, but what the 10W LED needs is a constant 333 mA. Frank (...)
In my IC i only want to use MOS for to design various component. In this how will i make current source?? Also describe in MOS, if source is connected to gate thn what is the significant of this type of circuit ??
555 is spec'd to +/-200mA output. With max rated at +/-225mA. Meanwhile, your R8=10 draws 1.2A spikes. Bad form. FET needs high gate current only to switch internal charge then low current. To improve you need to buffer the 555 such as complementary source or emitter followers, then R8 can be reduced to 5 Ohms or whatever max Gate (...)
I want to measure resistance and capacitance at Y port Connect a unit current source with ac magnitude=1 and any frequency between your output and gnd (separated by a large cap, e.g. 1F, in order not to short-circuit the DC output voltage). Then run an ac analysis, sweeping the frequency between your points of inte
Attached is a LTSpice circuit of a simple constant current source. A standard pnp / zener arrangement. I've used this circuit years ago , but I don't remember it being as good as the simulation suggests. Set for about 1mA output , it only varies by 25uA with a temperature change from 20 to 80 degrees and a load change (...)