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12 Threads found on Jfet 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
Hello, I'm looking for a fast p chanel jfet or mosfet which is on with a Vgs=0 and goes off with a Vgs>0. I'm looking it because i want fo do CMOS inverter to do an oscillator. I means the transistor must be in satiration state with Vgs=0.
I have never analyzed a Wien Bridge oscillator until now and I have never read one of the thousands of explanations about it on the internet, but here is what I see: 1) R1, R2, C1 and C2 form a bandpass filter that peaks at one frequency and applies positive feedback to the opamp to cause oscillation. 2) R3, R4 and the jfet provide negative feedba
hi, I would agree with 'kam' how many discrete steps would meet your your requirement.? Looking at the d/s I would consider the current control method, say using a P type jfet as a controllable current source. IMO a 10 or 20 turn precision potentiometer would be the easiest solution. E
Yes, this was a design I did in another post. It can easily be altered for use with a jfet.
Hello, I have made a jfet pierce crystal oscillator that outputs 3vpp sinewave on 1Mohm oscilloscope. I would like to amplify this signal and lower a bit the impedance. I have used this buffer with MPF102 fet and 1M gate resistor. For the source resistor I have tried 1M, 100k and 1
For me the circuit was working fine up to 400MHz starting from few MHz. At that time I remember I used a PNP with ft about 800MHz and a jfet almost the same. Usually is hard to find high ft PNPs. BFP640 is NPN and the circuit use PNP. The oscillator is sensitive to the type of diode, which should be a fast Schottky diode, and also is sensitive to
It will be difficult to make a crystal oscillator at 32kHz with a single BJT because of impedance loading. Such an oscillator can be done with a jfet implementation. Look at this thread
Hi again I need to Sketch the circuit of a Pierce crystal oscillator and explain its operation A jfet + a crystal in feedback path will result in pierce oscillator ( usually from Drain to source ) . . And also need to answer In what mode the crystal is excited crystal is used in series mode of resonant ! By the way
Your cicuit doesn't have a chance to work. Reduce R2 to 470Ω, remove capacitor C2, move resistor R1 to between base and emmiter and reduce it to 100kΩ, change C1 to somewhere between 2-20pF (use variable C) change BJT to jfet (2N5484) and it might work. What you got then is Pierce xtal oscillator. Oscilloscope is one of most im
I think the equations are correct. The next step would be to break the whole cycle into regions where we can break the jfet into regions of operation and solve these equations in those regions to calculate the whole cycle time period and hence the frequency. I am thinking about this, will post as I progress. Seems to be a very interesting exer
Hi, Anybody knows the design of jfet Crystal oscillator for 10MHz. I designed the oscillator it is running fine in simulation but when I am putting it on board its going weird-----No output.Please suggest me the changes to be made in order to make it oscillate.Please find oscillator cct attached