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1 vote

How does this delay circuit work?

The circuit you show is called a relaxation oscillator. It's also called an astable multivibrator, which is essentially a flip-flop with phase-shifted feedback to make it oscillate. The capacitor is ...
hacktastical's user avatar
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1 vote

What is ground in a physical circuit?

The terminology commonly used in electronics is a bit unfortunate* because (at least in my opinion) it makes this concept harder that it needs to be. An alternative term for "ground" is &...
bta's user avatar
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1 vote

How would this circuit work with a directly heated cathode?

The original 1927 patent from Edwin Colpitts himself shows a vacuum tube oscillator with a directly heated cathode. The component symbols are different from our modern ones, but I don't think it's ...
Spehro Pefhany's user avatar
1 vote

What is ground in a physical circuit?

In the physical context, all the ground symbols represent the same node. Every node which is connected to ground, using the same triangle symbol , is physically connected to every other node with that ...
Simon Fitch's user avatar
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3 votes

PUT relaxation oscillator problems

The circuit shown above should work without issues, and flash the LED every few seconds. There is not really much to go wrong in these circuits if you keep the divider resistance down relative to the ...
Spehro Pefhany's user avatar
1 vote

How would this circuit work with a directly heated cathode?

Addressing OP's comment on another answer, Why would a choke/resistor be needed on the B+ line(apart from plate short)? Doesn't a choke basically act like a filter for HF noise? Principles used: AC ...
Tim Williams's user avatar
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2 votes
Accepted

How would this circuit work with a directly heated cathode?

Yes your oscillator should work. Your little battery valves will have less transconductance so if it does not start reliably then increase the feedback and don't forget to place a choke in the B+ line ...
Autistic's user avatar
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1 vote

Calculating capacitor charging and discharge time using LM311 as Schmitt trigger astable multivibrator

I calculate the threshold voltages at 1.45V and 2.14V using an output voltage of 0.17V (low) and 5V (high), taking into account the 1K pullup (but not the 10k to the capacitor). Simulated values are 1....
Spehro Pefhany's user avatar
1 vote

Calculating capacitor charging and discharge time using LM311 as Schmitt trigger astable multivibrator

First, we need to find the threshold voltage. If we assume that LM311 is LOW (0V) then the voltage at V+ will be equal to: $$ V_{TL} = V_{CC} * \frac{R_2||R_4}{R_1 + R_2||R_4} = 5V * \frac{7.96k\Omega}...
G36's user avatar
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5 votes

What is ground in a physical circuit?

"Ground" mainly is an abstract concept. It is the voltage node you use as a reference point for all other voltages in the circuit. Because when we say this point/trace/pin is charged to ...
jusaca's user avatar
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12 votes

What is ground in a physical circuit?

Ground is what you define as the 0V point of a circuit. So you simply have a +9V supply in reference to 0V GND and a -9V supply in referenve to 0V GND. The total supply is two 9V batteries or 18V. For ...
Justme's user avatar
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1 vote

Does PLL stabilize the frequency variations of a crystal oscillator?

With a digital PLL multiplying your reference, the MCU clock will always be N times your reference. If the reference changes 1%, the MCU clock will change 1%. 100 ppm (0.01%) variation is trivial and ...
Neil_UK's user avatar
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1 vote

Does PLL stabilize the frequency variations of a crystal oscillator?

A PLL multiplies the running average of the input frequency over past cycles. A running average is a low pass filter, so it essentially low pass filters the rate of change of the input from the ...
user1850479's user avatar
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2 votes
Accepted

Does PLL stabilize the frequency variations of a crystal oscillator?

If you draw a block diagram of a typical PLL, the answer becomes obvious. The frequency divider is inserted in the feedback path. PLL from Wikipedia The output frequency will always eventually follow ...
Mattman944's user avatar
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1 vote

Does PLL stabilize the frequency variations of a crystal oscillator?

A slow time constant in the PLL can filter phase noise and make the clock more stable for short time periods. But the crystal will be responsible for the long time drift (long in terms of longer that ...
jusaca's user avatar
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4 votes
Accepted

Why my RC-oscillator design does not produce any output?

first thoughts The RC phase shift oscillator is often studied in a somewhat more ideal circumstance; usually using an opamp to make things a bit more idealized. Using a single bipolar transistor as ...
periblepsis's user avatar
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1 vote

Why my RC-oscillator design does not produce any output?

If you want all three RC stages to have the same corner frequency, some modification is in order. The aim seems to be an RC product of \$1k\times 100n\$. You'd like R1 to be lower (ideally zero from ...
glen_geek's user avatar
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2 votes

Are these filters suitable for this application?

Are those listed filters suitable for the task? And wich one of them is better? The best solution would be to use a passive 3rd order filter as shown in the datasheet. An active filter is unnecessary ...
Raonoke's user avatar
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2 votes
Accepted

Why do some JFETs oscillate and others don't?

models and datasheets The MMBF4416A datasheet you provided is terrible. There are no charts given. Nothing to examine. However, my eye is drawn to this: If you now set this up in LTspice where \$V_{_\...
periblepsis's user avatar
  • 11.2k
3 votes

Why do some JFETs oscillate and others don't?

Made with microcap v12, interactive mode "Stability" analysis. Just change your C1. It will start to oscillate within 250 us ... Tried until 420 MHz.
Antonio51's user avatar
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0 votes

Why do some JFETs oscillate and others don't?

JFETs have very spready DC characteristics .I have not used them in any high volume products due to fear of a production disaster. Sure people do and seem to get away with it .Try reducing R1 to get ...
Autistic's user avatar
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1 vote
Accepted

PCB microprocessor 16MHz oscillator layout feedback

The schematics are now correct regarding the crystal not being grounded from one leg. But AVRs do not need a resistor between the crystal pins, and even if they did, the 10 ohms would be completely ...
Justme's user avatar
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1 vote

PCB layout for 16 MHz crystal oscillator

The whole reset/crystal circuitry is wrong so it won't even work. Please look at data sheet or hardware getting started guide appnote or even look at the Arduino board schematics you seem to have ...
Justme's user avatar
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6 votes
Accepted

PCB layout for 16 MHz crystal oscillator

No it is not acceptable, the crystal needs to be close to the pins to minimize EMI. In this case I believe the pins are named XTAL1 and XTAL2. From each pin you should have as short a trace as ...
Lundin's user avatar
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5 votes

PCB layout for 16 MHz crystal oscillator

Is the layout acceptable? You should use a full ground plane for this type of design. It cost pennies to make your PCB 4 layer from 2 layer and will save you hours of messing around trying to locate ...
Andy aka's user avatar
  • 465k
1 vote

Are inductors in resonant circuits dangerous? They produce very high voltages

It is true that at resonance, voltage across an inductor in a resonant circuit can be large...especially so if resonant components have high Q (quality factor). If one is building a power oscillator, ...
glen_geek's user avatar
  • 26.7k
1 vote

Where is the phase shift on this oscillator?

Here is a simulation microcap v12 that shows that this circuit can "oscillate" ... and at what frequency ... Note that I added some "parasitic" components. Serial resistor with ...
Antonio51's user avatar
  • 14.5k
3 votes

Are inductors in resonant circuits dangerous? They produce very high voltages

When you touch it, the human body will be adding capacitance to that circuit model, so it will quickly drop out of resonance. Thus, only the small charge in the cap at the time of touch will discharge ...
Aaron's user avatar
  • 8,061
2 votes
Accepted

Will a circuit oscillate at all its resonance modes or only the most dominant one?

Ultimately, an oscillator is a nonlinear dynamical system; which also puts it in the class of chaotic systems. Well-enough behaved oscillators typically exhibit a negative-resistance characteristic ...
Tim Williams's user avatar
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1 vote

Are inductors in resonant circuits dangerous? They produce very high voltages

They can be, just like any circuit that generates high voltages can be dangerous, regardless of if it uses resonance, charge pumps, electromagnetic conversion, etc. Resonance requires specific ...
vir's user avatar
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2 votes
Accepted

How can this Clapp JFET oscillate when its gate is tied to ground at the resonance frequency?

By re-arranging the resonating L's and C's, it may help understand where resonance occurs. The two arrangements shown are electrically equivalent: simulate this circuit – Schematic created ...
glen_geek's user avatar
  • 26.7k
0 votes

How to make an oscillator using 3 legged ceramic resonator and transistor?

the 3 pin ceramic resonator has integrated capacitors to ground. try removing the external capacitors in the base circuitry.
user385001's user avatar
1 vote

How can this Clapp JFET oscillate when its gate is tied to ground at the resonance frequency?

How does the circuit below oscillate? I have simulated this circuit with microcap v12. Found that it oscillates when the serial resistor (R3 with 100 uH inductor) value is < ~ 30 Ohm. Stability ...
Antonio51's user avatar
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6 votes
Accepted

Where is the phase shift on this oscillator?

There's parasitic capacitance in various places of this circuit that can easily make it oscillate, see orange C's in altered drawing: Obviously we get oscillation if we have the \$180^\circ\$ phase ...
Jos Bergervoet's user avatar
0 votes

What is the oscillator in this 433MHz transmitter?

The LX1527 User's guide shows a somewhat different oscillator circuit that adds a surface-acoustic-wave (SAW) resonator to transistor base. It is a type of Colpitts oscillator. simulate this circuit &...
glen_geek's user avatar
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0 votes
Accepted

What requirements of a feedback network are needed to produce oscillation?

Practically speaking, such a feedback network will attenuate. Not at all if you choose the right type of topology (such as the common emitter Colpitts oscillator): - If you break the loop (dotted ...
Andy aka's user avatar
  • 465k
0 votes

What requirements of a feedback network are needed to produce oscillation?

In short: In order to satisfy Barkhausen`s oscillation condition we have the following criteria: For a non-inverting amplifier the feedback network must be able to produce zero deg phase shift at one ...
LvW's user avatar
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3 votes
Accepted

Why does the voltage increase when I connect this amplifier to a gate driver?

You're going to need to drive both the high and low harder. With your circuit a current of 100 uA, which is within the gate driver's specced input high range, will drop 3.9 V across the collector ...
GodJihyo's user avatar
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