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112 Threads found on edaboard.com: Variable Capacitor
The formula is for minimal bootstrap capacitor (an inequality in mathematical terms), so the answer in case of a variable time period should be clear.
IF you can open the probe in a way that allows it to be reconstructed, all you will find inside is a variable capacitor (compensation control) and one or two small resistors. In view of the overvoltage condition, I would replace them all. The parts cost is almost nothing but you might need a degree in neurosurgery to handle the
Ultrasonic transmission requires both TX and RX transducers to resonate at the same frequency. Try adding variable capacitor (10-300 pF) in parallel with one transducer, if no improvement, then to the other. Use a parabolic reflector on one or both sides to increase directivity. Try checking the waveform with an oscilloscope before the amplifier
Hello, Please could you check the attached fan drive circuit for driving the "ebm papst 8218 JH3" fan? Please advise if this circuit is OK? Basically, as you may see, it is driving the fan from a Buck converter. Do you believe that the 10uF capacitor across the fan is enough capacitance? The PWM is at a frequency of 100KHz, and its duty is
Dear all, I need variable capacitor, working at 1-2GHz, with capacitance of 1-5pF. I hope the Q is high enough, such as 200. Can you recommend? Thanks. Yun
It's not strictly MPPT. Rather a variable Vin regulator implementing the function Vin = a + b*Pin
Hi I want to build a variable low frequency generator. Frequency range: 8Hz - 200Hz Duty Cycle: 20% - 30% I could not work out a suitable configuration for a 555 because the duty cycle conflicts when the frequency is increased. Can anybody help me with this issue? Ah yes, 555 is not compulsory.....other devices like op-amp or transisto
I have an incoming variable frequency (1 KHz to 20 KHz) and variable duty cycle pulse. I need to convert the duty cycle into an analog voltage between 0 and 1. I do not have the luxury of RC filtering the pulse using an external capacitor. What is the simplest way to implement this function on chip?
Does anyone know any recent technologies that allow for a variable capacitor with Inductor with high Q . I have seen MEMS - anything else? thanks
Problems of the circuit: - as a trivial point, bootsrap capacitor wrongly connected - voltage control loop has high gain and can't be stable - voltage control loop has wrong polarity - current control loop has wrong polarity - voltage and current error signals are combined in a way that can't achieve the intended effect It's not correct t
Hi every body. pls, can any one support me? I need connecting lumped element(variable capacitor) to resonator using cst simulator. warm regards.
In fact capacitive microphones are nothing more than a variable capacitor so needs to be biased. No. Look in Goggle and you will see that the electret mic (that we are talking about) is a condenser mic with a high voltage built into its electret material. It makes a variable low value capacitor with the movin
Do you mean checking how the results change when varying a variable value?
I?m developing a simple, five-frequency superhetrodyne receiver to operate between 2.5 MHz to 20 MHz in which the local oscillator crystals and whip antenna tuning circuits are selected (switched) using diodes. Here?s the problem: The whip tuning circuit is comprised of a single variable capacitor with five fixed-valu
Hello all. Does anybody know how to design the typical VGA for a commercial TV preamplifier? In the picture attached, i dont know if the trimmer (7 to 22 dB) is a variable resistor or a variable capacitor. How does it work? Thank you. 92309
Maybe this can give you some ideas :
I've built a variable voltage DC power supply circuit using an SCR, rectifier and 160v 33uF capacitor. I've got a 7-150v DC voltmeter hooked up to display the voltage. It always reads 160v, even if I use my multimeter. If I remove the capacitor, I get true voltage readings. How big of a load do I need on it to get the correct voltage to (...)
Hello I have a series L/C circuit connected to a vfo. I am trying to figure out different ways to tune it. Right now I am thinking the next ones: 1. L stationary, C mechanically tuned (variable capacitor) 2. L mechanically tuned (inserting or removing cores), C stationary 3. L stationary, C varicap 4. L electrically tuned (varying magnetizati
Hello guys, I'm trying to design reader device for RFID applications. But important thing is that frequency will be variable. For this purposes I can use to options: either for different frequencies use separated output stage with chosen value of capacitor or use one output stage and somehow vary capacitance. What is also important: i use microc
When you say MOS diode are you referring to the diode formed by the drain-bulk PN junction, or something else? Technically MOS diode is a term for a MIS structure which behaves like a variable capacitor, not a diode...
Recently I have to achieve 1KW 13.56MHz Plasma power supply for Vacuum Plasma I?ve no any RF PA background, but I?ve already studied ZVS Class-E PA and Impedance Matching for about a month, I still have plenty of questions. The equivalent Impedance after igniting, is about 500 Ohm and equivalent capacitance in parallel, but stil
HI i want to have a variable capacitor in ads.this capacitor is a model of a mems microphone.please help me and help me for matching this capacitor with microphone amplifier thanks for your help - - - Updated - - - i want to have a capacitor that variable with voltage and have a flat (...)
Hi, I need to design a variable capacitor SPICE model. I want to do it with look-up table which would contain a C-V characteristic. Can it be done? I simulated a IDC with HFSS and now I want to include the results in Spice model. I never used Spice so I do not know how to do it. Can you help me? Thank you
The only way to make a free running varicap tuned oscillator to be as stable as a variable capacitor (mechanical) oscillator, is to reduce as low as possible the gain of the VCO (MHz/V). But in this situation you lose frequency range.
Define an equation that relates your voltage changing to capacitor value and put this variable in capacitor component as its value. For instance MyCap=0.5*Vtune+10*log(Vtune) etc.Then put this variable into cap value like C=MyCap. It's so straightforward..
hello Why are you using integer for f1,f2,f3,cal1 ? what is the purpose of cal1 and f3 try con1= cx / ((((float)f1/(float)f2)^2)-1); or pass all your variables in floating point format. and you will get 402pF
I have been trying to make a variable capacitor based off of a lookup table in PSPICE. I found a paper by cadence, A Nonlinear capacitor Model for Use in PSpice, which gives a method of creating a variable capacitor but I am unsure how to actually write the .lib file to implement this design. Any (...)
I think it was just to allow flexibility in the wiring layout; in pre-PCB days the wiring was "point-to-point" and a choice of connection point would have been useful since variable capacitors could be mounted in different ways. Both connection points could be used for different components if the chassis layout made that convenient. You don't hav
That "common" connection in the centre is actually connected to the spindle, so in that circuit, when you touch the knob on the spindle you will be adding extra capacity across the bottom capacitor. Just use one section of the variable capacitor, WITH THE CENTRE CONTACT earthed, and wire a fixed 68Pf in series with it. Frank
i am unable to use the variable capacitor in my circuits,i.e, which pin of variable capacitor should be connected to which point in circuit?76193 76194
Hi there, Just joined up to the forums, apologies if this thread is in the wrong spot. I am currently looking at designing and making a piece of test equipment to test the opening and closing time as well as minimum operating voltages of high voltage circuit breakers. The control circuit side of things is no problems but I am struggling to
See the attached diagram. In practice need to adjust the variable resistor P1 in order to obtain the accurate 1Hz pulse. Also need to determine the C1,R1 correct values for triggering the camera (start by using a 4.7uF - 10uF capacitor and some 4.7K up to 22K resistors). Press button 'LOAD/START' to start automatic counting down sequence when
On your schematic, the Colpitts-type oscillator is shown. The capacitors between transistor base and ground are calculated for a coil in place of the quartz crystal. The L1 in collector is tuned by 250 pF variable capacitor to resonate at 3.56 MHz for a good oscillation. Fine tuning can be done with 50 pF VXO in series with the quartz. Find (...)
Why not call it a varactor diode and put a variable sinewave across it? Frank
L1 and VC1 (variable capacitor) make the tuning circuit to get signal of the radio stations' transmission and the received signal is amplified through Q1 amplified by Q2 and fed back to the tuning circuit (regenerative circuit, some times known as Autodyne, too, regenerative means amplified many times by the same active component, here the Q1 and Q
Yes, 9x1.414=12.7 Volts. 9 volts is the RMS value and when you rectify it and treat smoothing with a smoothing capacitor in the circuit you get Peak voltage, which is 12.7 volts per your question. Now regulating it for 5 volts fixed or using a variable regulator you can get as much as you want within the range minus regulator drop volts. Here is a
Hello, How to put variable capacitor, RF input, ceramic capacitor in AWR MWO and for an circuit, in data sheet if it given RF input, does that mean it is HB port(PORT1). Are these elements available ? cheers
Hi, I want to build a power supply @ 25v a/c in and a variable 0- 20vdc, 10a max out. So that?s the plain. After the rectifier, I want to put a capacitor to smooth out the pulse. Now my question is: Does anyone know the formula to find the UF capacitance? Plus and minus information on error sizing would greatly appreciated, for since my current wi
Here is most commonly used ways to control capacitance value. variable capacitor - Wikipedia, the free encyclopedia Varicap - Wikipedia, the free encyclopedia connecting capacitors in serial or parallel with electronic or mechanical switches
Should your project be something novel ? or you can simulate some devices which are already designed (ex: RF switch or variable capacitor).
Hi, Refer the attached FM jammer circuit. I am trying to build the same. but not able to make it work. can some one review the sch and tell me is it fine? I am using the transistor 2N2222a with TO92-3 plastic case. Also for the 6pF capacitor i am using 4.7pF and 1.15pF in parallel. For the variable capacitor i am using 6.5-30Pf (...)
variable capacitor 100 pF have 3 pin, i need datasheet for its and pin configuration? Thanks Riski
Hello guys, I want to build a switch capacitor half-delay integrator for one second order switch capacitor sigma-delta modulator in SIMULINK. Here, the transfer function is z^(-1/2)/(1-z^(-1)). I can use the unit delay model to realize 1/(1-z^(-1)). I know I can use the variable fractional delay model to realize z^(-1/2). It works fine in (...)
hi all i want to design smps with variable output from 1V to 50V. i have seen on the net how to select the circuit element(inductor capacitor) for fixed output. BUT since i have to vary the duty cycle in order to have variable DC, i dont understand how to find the circuit element values.
I have to design a NVIS roof rack antenna for the following specifications. Frequency range: 3.3 ‐12.5 GHz. Power rating: 125 PEP Receive bandwidth: 45 KHz at 3 GHz and 290 KHz at 12.5 GHz. Tuning method: Continuously variable tuning capacitor. Drive Method: Microprocessor controlled precision stepper motor. Dimensions: Standard rack
hi i design a project that i use HS1100 humidity sensor.i use it as a variable capacitor and change its variation to frequency.i will send u my project file.simulation in proteous and code in code .vision
Thanks guys for yours replays, probably my question was generic too. My problem is to realize a custom circuit that can generate a square wave form with variable duty cycle and fixed period.
Yes you can use this IC for variable output, For mains step down transformer, rectifier & Filter capacitor design you will have to follow the same calculation as linear power supply , (although filter cap can be optimized if your lowest ripple tip is higher than your max output voltage i.e. for 15V output it can be 3V higher at full load). Note
i want to build a long ( 1km - 2Km) range fm transmitter as a project work but all the circuit i have come across have variable capacitors which iam finding difficult to get at my location ( Ghana):?
hi all i did model in HFSS,it OK but when i did that in CST no change?why? i use capapcitor with variable capacitance values it done in HFSS but fail in CST so some help,i will be appreciated abdoeng