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171 Threads found on Capacitor Voltage Source
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
Your circuit isn't well considered. The PMOS transistor will stay on as long as V(output) is above Vth and discharge the capacitor to input voltage source.
Without UIC option, the initial generator voltage of 1.2 V is applied and capacitors are precharged. The floating output node, although its voltage is undefined as mentioned by KlausST, is pulled in Ltspice to 0 V by a default minimal node conductance. This behavior depends however on various analysis options and might be different with (...)
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
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.
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).
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.
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
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 (...)
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 (...)
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.
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.
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 (...)
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.
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 (...)
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 (...)
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 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?
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 (...)