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Capacitor Voltage Source

171 Threads found on edaboard.com: Capacitor Voltage Source

help me design tubed version of the fet oscillator

They say a jfet is like a triode. I want to design a triode version of this oscillator the source gate capacitor is formed by the internal capacitance of the fet, but I won't mind adding one in the tube circuit. the tube will be the 12dw8 operating at an anode voltage of 12v. Please give me hints where to star

Hold up capacitor design using MOSFET

Hi, I have to implement the 20ms ,50W Hold up circuit in my design.The voltage is 12V.Based on this, I implemented the MOSFET with 220mF capacitor based Hold up circuit.While simulating the circuit,the cathode of D1 waveform is different from capacitor output.Altenatively,If I replace the diode instead of MOSFET,Im getting the proper (...)

charging and discharging of the capacitor using two pulses of 180 phase difference

Hi, The DC voltage at the middle is undefined, because both capacitors are high impedance for DC. But with precise input signals it won´t change. Theoretical no AC signal. **** Short circuit both capacitors and the middle voltage will be DC 0.6V Klaus

hi, On a simple circuit like that I would use a low value resistor in series with the source connection of the MOSFET. Sense the voltage drop across the resistor using say a LM393 comparator. Add a resistor/capacitor filter on the input or the output of the comparator that connects to the sensing control On/Off. E

Problem with design of a peak detector

This indeed look a like stability issue for the opamp. With the probe in place, what is the phase margin and gain margin you obtain? Check with some initial condition on the capacitor, by inserting a voltage source in series with the capacitor.

negative bias voltage generation

The shunt capacitor doesn't help at all for not losing efficiency, if you place a source resistor in a power amplifier stage. The shunt capacitor helps only in a low signal stage (as an LNA) to don't reduce the gain of the amplifier (due to signal loss through the source resistor).

Input Capacitance of Comparator

Calculate? I wouldn't. Simulate by referring a cccs to the stimulus source and push its output onto a 1pF capacitor. voltage step there, at any input edge transition, is your input charge in pC. Scale by input step voltage value to get capacitance in pF.

Voltage controlled resistor circuit question

With a series capacitor between the (current source?) and the upper RX terminal, it doesn't look much like a resistor to me. The mentioned photoFET optoisolator is only linear for maybe +/-100mV and then rolls over. Not a good general purpose "resistor" for anything but true small signal (as the datasheet itself makes plain). I wonder about some

Coupling capacitor in amplifier

Rg sets the gate at 0VDC. The current source between the negative supply and the source sets the Mosfet bias and current. The drawing is wrong because the source will not be 0V but it will be some negative voltage for an enhancement Mosfet. when the source has the same voltage as the gate (...)

Input Capacitance of cmos inverter chain

You can step voltage and use a cccs referred to the input voltage source to integrate the charge onto a (say) 1pF capacitor, then voltage is the charge in picocoulombs. There may be more realism when you apply a sensible (i.e. circuit-realistic) rise (or fall) time to the front end. You may need to (...)

Amplifying AC voltage via DC supply voltage

You are perhaps getting noise from the mains. I'm not sure, but you could try reducing the value of the input capacitor, something like 1/10 or less.

Nuvotone 8 Bit MCU W79E2051

Yes, you cam make your own A/D converter, and it's not too dificult to understand. With a constant current source and a small capacitor, you can generate a saw teeth waveform, which can be used to compare with measured signal. The time elapsed to reach the same value is proportional to the voltage.

frequency to voltage conversion

for these super low frequencies, use a current source/capacitor ramp generator circuit. Start the ramp at the positive going zero crossing of the input sine wave, and reset the capacitor to 0 Volts at the negative going zero crossing. Save the peak ramp voltage value in a simple diode/hold capacitor and (...)

Newbie RC Filter Question

Your schematic shows no filter, it is simply a voltage limiter consisting of R 65 and CR 11 (a Zener diode). The capacitor is not necessary. If it might filter anything then one will need to know the Vin source impedance.

JFET common source amplifier

But a Jfet is a depletion FET, its gate needs to be below its source voltage so a voltage divider is needed at the source, not at the gate. A single source resistor to ground will bias it and the gate can be at 0VDC. The source resistor can have a parallel bypass capacitor (...)

[Moved] Help Regarding Peak To Peak Detector Circuit

The schematic shows a peak detector but onl one polarity. Not peak-to-peak. In the schematic the internal source impedance is missing. If you have 550 VAC source, then the capacitor (100 uF) will charge to a peak voltage of SQRT(2) x 550 V, or 780 V. I doubt you can find such capacitor on the market. (...)

What do you mean by "established" bias voltage? What do you think is the meaning of Vcm1 and Vcm labels in the original Filter Designer schematic? Names for floating circuit nodes? Vcm1 must be obviously connected to a voltage source or a bypassed voltage divider, Vcm at least to a sufficient large bypass (...)

Electrolytic capacitor ESR not specified in datasheets, can it be estemated?

Hello. I am looking to buy some 10?F electrolytic capacitors and while reading the datasheet: I can't find any info about impedance or ESR, I do know that I do not necessarily need to know that about this cap. They will be used as general purpose decoupling paralleled wit

How do I know that the esr meter measures the internal resistance of the capacitor ?

How do I know that the meter is measuring the internal resistance of the capacitor and not the reactance? How can I identify when it is of a kind and when the other?

Video DC level restoration

This is normally done with a simple diode and capacitor arrangement. The capacitor charges to peak video level and that voltage is then referenced to a fixed voltage. A good source of information is the CQ-TV archive at but it seems to be linking to the article software rather than the magazine PDFs at (...)

how to find RC time constant of series parallel circuit?

A simple method is to assume that the capacitor is charged - and to determine the resistance for the discharging process. Assuming that R1 is connected to an ideal voltage source (zero ohms source resistance) the resulting time constant is T=(R1||R2)*C. As another method, you can find the transfer function. If it is (...)

how does this integrator work?

A gm-C circuit (OTA + capacitor) is perfectly working as integrator, if it's feeding a high impedance load, e.g. a MOSFET buffer. You should be able to find plenty of literature examples. The resistors provide "source degeneration", reducing the OTA'S gain and increasing it's linearity and input voltage range.

Selection of Bypass(decoupling) capacitor for high spike currents,voltage drop probem

Low ESR is already presumed for the ectrolytic capacitors

Question of calculating impedance in time domain

In a practical sense, if both time constants, T1, T2 are greater than the triangle ramp period, then the ripple may be straightforward. V=I*ESR , where ESR = R1//R2. The voltage ripple is regardless of value of capacitor. With source current suggested as bipolar triangular , this results in triangular voltage ripple.

How would I increase the power of a device?

Since energy is power per second, power can come from many sources. With lower source resistance source power is P= VxI, if discharging a capacitor P= 1/2 C*V^2 or storing power in an inductor P=1/2 L*I^2 ... Or solar power ~ 20% of full sun power=1KW/sq.m. solar panel using ~70% of open circuit voltage (...)

problems about CMFB of a full-differential two-stage OPA

Hi guys, I want to design a full-differential two-stage OPA. The first stage is telescope cascode structure and the second on is usual common source structure. I want to use switched-capacitor CMFB to make the output common-mode voltage stable. I am wondering now that how many SC-CMFBs I should add in the OPA. One SC-CMFB only for the (...)

Which way is the best for dividing the voltage?

Without the common ground you will have to use a capacitor voltage divider May be appropriate in special cases, but hardly a general solution, I think. A differential voltage divider (resistive or compensated RC), as it's used in differential oscilloscope probes should be widely applicable.

Filter noise from a DC power supply

you can by a 100nF capacitor at the output of your source .. as in 7805-binding scheme. Hope that

o/p of dickson charge pump with dynamic cts is not coming

Questions: * Your schematic has several stages. Did you try a single stage? Did it work? * Are your mosfets biased to a sufficient volt level so that they turn on? (It needs to be greater than the node at the source pin.) * Which capacitor accumulates the output voltage? The neighboring mosfet needs to be biased several volts higher.

problem in the workink of rc circuit in DC source

Obviously, the capacitor charges with DC current from the battery. The amount of current is limited by the resistance. The capacitor voltage rises to about 63% of the battery voltage in "one time constant" which is R in Ohms times C in Farads. When the capacitor is fully charged then no more charging current (...)

Bypass capacitor/s to cancel out noise.

a pi filter would help - to greatly reduce noise from the motor a blocking diode after the electrolytic capacitor - it keeps the voltage 'high' for the control board a reverse diode to inhibit reverse EMF

Output resistance Operational amplifier !

Hi my friend ! I am using top spice. I connected in the output a current source AC 1 and then I did an AC sweep between 1 hz and 10 Mhz. The plot I obtained represents the output voltage versus frequency. In the output I have a capacitor of 10 pf. At low frequencies the plot correspond to the output resistance (Ro) and at

Generate a single-shot pulse from low voltage/current source

You could use some low quiescent current step up converters as NCP1406 to get 24V, then use a resistor to limit the 24V current to 10-15mA (which will result in 100mA current from 3V) and then put a capacitor 500-1000uF after the resistor to store the 24V energy. When you connect something to the capacitor it could bring you currents even bigger th

Depletion Region of reverse bias diode

Is the capacitor charged to a different voltage than the diode? Is this perhaps a charge-division homework problem?

need help to calculate the inductor and capacitor value in z

hello everyone, i need help to calculate the inductor and capacitor value in z source inverter please thanks in advance

How to understand charge sharing in charge pump of PLL?

if there is not a unit gain opamp, voltage of node N1 and N2 would not change too much , so charge sharing is not terrible. N1 and N2 are floating up to the supply rails minus current source saturation voltage, the parasitic charge transferred to the loop capacitor might be "terrible" enough, CS saturation possibly causes (...)

What is the difference between high side driver & low side drivers..??

Moreover, to deliver the voltage that fires the gate of the high side fet, you normally will have to use a bootstrap capacitor to trap enough voltage and use it to fire between the gate and source of the high side fet. - - - Updated - - -

Simulating a current load in LTSpice

It's exactly what happens in a real circuit when the AC input voltage (or the capacitor) is too low. Do you understand that 15V magnitude in sine source refers to peak value corresponding to about 10.6 Vrms?

ac signal peak detector

96158 here is circuit diagram of a peak detector i need its explanation. i want to know its workng. whats each component is doing here eg capacitor diode resistor, mode of op amp? and what if i use LM741 op amp and 1n4001 Diode? kindly reply. thanks

How to design a bypass capacitor?

how to design bypass capacitor?Normally we use 0.1uF for bypassing (VCC to GND)in digital there any calculation for this?

Basic AM Receiver Design

The schematic is almost correct. On the left, the AC source should be coupled to detector diode by another capacitor to make sure the DC circuit is not affected by AC source impedance. If you noticed, the DC source has 0.7 V DC voltage which "opens" the detector diode into an optimum operating point, with (...)

Parallel LC circuit behaviour in dc

Of course, it does not oscillate. Here, the voltage of capacitor is fixed to the supply voltage and the current of inductor rises linearly with time: Ldi/dt=Vdd ==> i=(Vdd/L)t. therefore, it produce magnetic field and even even electric field (E prop. dB/dt). Because the capacitor is in parallel with supply, having or not (...)

How to generate a ramp voltage in Cadence SpectreRF (or AMS)?

For simulation purpose, use a piecewise linear (PWL) voltage source. For a real circuit, inject (constant) current into a capacitor and use a reset circuit.

LED indication in triac switching

Basically you want to drive LED with AC source... For this you can use capacitor voltage divider instead of voltage divider. there will very less dissipation in capacitor voltage divider. One important thing is...18V across single LED is too much...Thats why it is flickering and died in 3-4 (...)

Voltage controlled DC sweep

A current source into a capacitor provides this ramp. The cap needs a switch to reset the charge and the current source needs a switch to enable. The output can be buffered with a low input bias FET op Amp. A FET can provide the current source. Can you figure it out from there? The cap should have low memory so a film cap (...)

Audio amplifier project

If the (+) and (-) inputs are swapped so that the opamp has negative feedback instead of positive feedback then the R4-R5 voltage divider is shorted to ground by the signal source because an input coupling capacitor is missing.

Electrolytic capacitor on battery powered circuit

If there is no dynamic load and no dynamic charger source voltage and hence no ripple then you do NOT need a cap because the battery dielectric is your capacitor. This is only needed if you have ripple noise. then cap with the impedance required to reduce the ripple is chosen where Z=1/(2pi*fC)+ ESR and often more than one value in (...)

circuit provide 500 V DC pulse

You need first a DC source with 500 V output. For an "extremely low current" you can use a capacitor charged to 500 V. From 120V AC, I would use a voltage tripler or a 120V/450V transformer and rectifier diodes rated to ~1 kV. As "the push button" must not be in the 500 V circuit", you can use a relay to transfer the 500V from the charged (...)

MOS used as a capacitance

lets consider NMOS. In accumulation your gate voltage should be lower than source potential - so the holes are attracted to the gate and so the capacitor is created between the poly of the gate, positive charge in channel which are divided by oxide. Co that is why the capacitance value is the same as in strong inversion - where instead of (...)

What?s wrong with the simulation result of the very basic RC circuit

...but my guess is that it places a voltage source with 1 ohm resistance at the Initial Condition node. ... Looks like that. It is as if a 1 Ω resistance were used to set the initial condition only, not as a part of the model of the capacitor: The time constant of the discharge is exactly 0.4 s, i.e. 0.1 F w