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Questions tagged [oscillator]

A device or circuit that generates an AC signal at a certain frequency.

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Could an external circuit with 74HC series IC reliably test a 24 MHz crystal?

I made a circuit where the microcontroller works. I made a duplicate of the same circuit with a working micro, but that circuit does not start and there is no smoke and the PCB is clean (no loose ...
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Identifying a LC oscillator circuit and solving resonance frequency

Could someone please identify what type of oscillator this is in the first stage. I'm not quite sure if it is a Colpitts or not and also could someone specify the resonance frequency calculation if it ...
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38 views

PSpice simulation of phase-shift oscillator doesn't work

I'm trying to simulate on PSpice a BJT-based phase shift oscillator, like in the following schematic: but when trying to measure the voltage on the node connecting R3 and R5 I only get DC voltage (...
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38 views

Interrupt generating circuit: 0 ~ +3.3 V

For the purpose of testing a MCU and it's interrupt handling I want to design a circuit to generate interrupts. Ideally I would use a relaxation oscillator, but my supply is constrained to 0V and +3....
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40 views

Sine wave generator using a triangle wave input

I'm covering oscillators in my class right now and in the foot notes of my professor's notes he says that there is a "dirty and cheap" trick to generating sine waves. I replicated the circuit below ...
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22 views

Inconsistent output in Multisim [closed]

The circuit which I draw in the multisim was correct and was showing the correct output but when again I started the simulation the same circuit was not showing the output!
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703 views

CPLD based Pierce oscillator

I want to make a clock generator for Altera EPM240T100C5N using the CPLD itself as a Pierce oscillator. This CPLD has Schmitt trigger inputs so I guess this should be possible. What I`m not sure about ...
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53 views

Simple amplitude modulation of a square wave oscillator

I'm in the process of creating a classwide project for an introduction to op-amp and transistors. My goal is to create a 49 keys synth that every students can contribute a small part, run test plan ...
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60 views

Relaxation Oscillator Issue, comparator self-oscillating at 25 MHz (40ns propagation delay)

I have a relaxation oscillator circuit, which is supposed to oscillate around 6 MHz, and mostly it oscillates in a very stable manner around it. However sometimes it starts to oscillate at 25 MHz, ...
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487 views

Why are the capacitors necessary for a quartz crystal?

I read that it is recommended to connect 2 grounded capacitors to both ends of the quartz crystal. But that doesn't make any sense to me. Since capacitors have no resistance, wouldn't that make it so ...
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82 views

Why are oscillators 'always' AC coupled with 1000pF?

Most of the time I see oscillator datasheets or datasheets for parts requiring external oscillators, the oscillator output is AC coupled to the part it's driving through a 1000pF MLCC. This ...
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90 views

PCB Crystal holder

I am designing a PCB consisting a microcontroller in which I have to ensure that I have removable crystal . I am looking for a female connector in which I can easily plug/unplug/swap the crystal (...
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What is the difference between BAW and SAW?

TI has recently (?) released some BAW (Bulk Acoustic Wave) based resonators, but SAW (Surface Acoustic Wave) devices has been around for ages. Most often SAW are found in mobile RF filters. This gave ...
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110 views

Using only stray capacitance for MCU oscillator circuits

I've included a diagram of typical Pierce oscillator circuit taken from ST Application Note AN2867: The note suggests that C_L1 and C_L2 should be chosen such that the following equation holds: ...
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85 views

How is it possible that an LC Oscillator create a sine wave?

I have a question, for example look at this circuit: 1)How is it possible if this circuit can oscillate, for example taking on the capacitor full charged, and the inductor full discharged, the ...
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32 views

Avalanche relaxation oscillator biasing resistor

I've tried the circuit in this article. It works very well and I've obtained 2ns clear pulses at 150 V (the main issue was to find the right avalanche voltage, which turned out to be 150-160V for my ...
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81 views

quartz crystal oscillator applied voltage

I know that in quartz watches a quartz crystal is used to keep time by counting it's vibrations, caused by the voltage applied to it. I don't understand if this voltage is DC or AC: If DC is used, ...
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33 views

XMega External Real Time Oscillator Capacitor Values

In application note AVR1012 (XMEGA A Schematic Checklist) Atmel states the following: The Low-frequency Crystal Oscillator provides an internal load capacitance of typical 8.0 pF. Crystals with ...
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55 views

AD5933 is not working with external clock

I am using AD5933 impedance measurement chip. There is an option to connect an external clock. I am using a function generator to give 250 kHz, 2-volts peak square wave signal to MCLK pin, but it's ...
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59 views

Resonance in Yig oscillators - is it normal?

The advertised range of my recently bought YIG oscillator is 1.1 - 3.4 GHz. On my spectrum analyser, I found 2 resonances, spaced at about 1 GHz and 2 GHz from the main peak (see picture below were ...
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1answer
54 views

Which type of oscillator should I use?

I want to make induction heater. So I want to make oscillator for this. I want to make oscillator with transistor, inductor, resistor, diode and capacitors but not IC, relay switch, op amps etc. Which ...
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31 views

SIMPLE digital control over 555 timer frequency and PWM?

I'm looking to create a sound generator with only simple ICs and components. I believe the 555 timer IC is a good candidate to be at the core of it, but I cannot for the life of me find out how best ...
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67 views

Negative pluse generator does not reach 0V

I'm using an Arduino board to generate a 125KHz square wave signal to feed into this curcuit: simulate this circuit – Schematic created using CircuitLab So this is what I'm receiving from my ...
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1answer
35 views

Op-Amp Astable Multivibrator - Effect of bypass Switch

For your consideration, I have this Astable-multivibrator via a classic Op-Amp Schmitt Trigger delivering a square signal (here 1.82Hz). I am fine with the circuit with SW1 open as C2 is basically in ...
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2answers
67 views

Low Signal from Single Transistor Pierce Oscillator Mysteriously Turns High

Yesterday, I was attempting to build a single-transistor Pierce Oscillator based on an old Application Note from National Semiconductor. According to the Application Notes, the following circuit was ...
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1answer
146 views

What is the purpose of the following inverter topology?

I stumbled upon an Schmitt-trigger oscillator circuit. I can fully understand the principles and its function, but what I cannot fully understand is the chain of inverters after it. In the above ...
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42 views

Voltage divisor on a oscillator output using Capacitors vs Resistors

My question is pretty simple. Why does this chip datasheet suggest to use a voltage divisor using capacitors? Does it make a difference to use capacitors instead of resistors? Edit: Link to datasheet ...
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81 views

Crystal oscillator producing straight line only

I have replicated a crystal oscillator circuit from internet, but the output waveform is a pure DC rather than the expected sine wave. Below are my circuit diagram and the simulation output from ...
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1answer
50 views

Phase Noise In a Voltage Controlled Oscillator

I am particularly new in VCO design. I am required to build a negative gm oscillator with f=7.4 GHz with a tuning range of 300 MHz. The phase noise should be -110 dBc/Hz at 1 MHz offset. I sized the ...
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3answers
139 views

PUT relaxation oscillator doesn't work

I'm following instructions from Charles Platt's "Make" and trying to mount PUT oscillator. Strangely, it blinks only once when I switch on the DC current, no oscillation was observed. I have tried ...
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1answer
56 views

Can I use a 5v xtal osc with a 3v MCU? Will a simple npn buffer work? [duplicate]

I have several crystal oscillator cans that run on 5v. I have a PIC24HJ128 on a breadboard. The PIC uses 3v. I want to use a simple npn transistor to buffer the osc out into the CLK in. Will this work?...
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1answer
57 views

CD4011 Oscillator Square Wave Output Fed to Transistor Audio Amplifier; Volume Control Question

I built an audio frequency square wave oscillator using 3 gates on a CD4011 quad NAND gate IC. I then fed the output of the oscillator (pin 11) to a very basic "push-pull" transistor amplifier on the ...
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46 views

Insights required to repair my Agilent YIG oscillator

I know, it's probably no chance. But let me try. The model is HP-Agilent 0955-0520, Y088-4258, that can be bought for 600-900$. Here is a picture. When I bought the oscillator, I performed multiple ...
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71 views

Crystal Oscillator (STM32F4)

I am currently working with a STM32F427 MCU and have a few questions in my mind. Is my schematic for the HSE correct? Can you tell me, why some schematics on the Internet use a Resistor in series ...
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1answer
110 views

BJT Clapp Oscilator for 3-6MHz

I designed a Clapp VFO to aid in my Ham Radio projects (Non-superhet SSB and CW recievers for 80M and hopefuly 40M). I chose the clapp topology for it's frequency stability. I want it to tune at least ...
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160 views

More Fun with the CD4093 IC as Schmitt Trigger Oscillator. Any practical difference between circuit version with “Enable” pin and Without?

I built two Schmitt trigger oscillator circuits using the CD4093BE IC from Texas Instruments. The CD4093 is a quad NAND gate with Schmitt trigger inputs. You can find the datasheet here: http://www....
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1answer
130 views

Using CD4093 as Schmitt trigger oscillator. How to measure high and low trigger thresholds?

Based on the suggestion of answerer in another post (this one: Adding Diodes to Transistor Astable Multivibrator; 1N5818 Schottky diodes work but 1N4148 diodes don't; can't figure out why), I ...
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2answers
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Designing a deterministic-startup precise oscillator

The problem I need to reliably generate a sequence of events based on a digital input trigger signal. With minimal jitter and a predictable deterministic delay. 2 to 5 events The events will be from ...
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3answers
147 views

Why the Wien Oscillator output is a sine?

I don't understand why the output signal of the Wien oscillator is a sinusoidal waveform. I can easily understand how a sine waveform can be generated by an oscillator which contains an LC circuit (...
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1answer
55 views

beat frequency oscillator

I'm a new student in electrical engineering. I'm trying to make a BFO (Beat Frequency Oscillator) circuit for my university project. I didn't understand the duty of 3rd transistor and capacitors ...
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2answers
57 views

How does load resistance affect the function of this crystal oscillator?

Related Load Resistor across Crystal - though that's for a passive crystal and not an integrated XO. Summary I'm considering using an Epson TG-5035C XO and am figuring out the circuit necessary to ...
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73 views

Does this clipped-sine oscillator need a buffer?

I'm considering using an Abracon VCTCXO, the ASVTX-11-121-19.200MHz-T to run an AT89LP428. I'm trying to make sure that they're interoperable, but the Abracon device doesn't say anything about the ...
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117 views

Why is my crystal oscillator not working with KSZ8999 switch?

I am using KSZ8999 ethernet switch from Micrel and I have problem with 25 MHz external oscillator. There is constant 2,1 VDC on output pin which is VDD for the switch, so crystal is not oscillating. ...
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407 views

Crystal compensation for temp and voltage

Introduction I'm toying with the design for a fail-safe wall clock controlled by multiple 32.768kHz crystal oscillators. I'm currently reading about compensation. Compensator from literature From ...
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90 views

Disable RC oscillator in ATmega328 for FCC compliance

With respect to the topic below, I was trying to find where in the AVR documentation does it say the 8 MHz RC internal oscillator is "disabled" when CKSEL is selected to a different source? I am ...
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84 views

Can negative feedback in OPAMP be applied at not inverting terminal?

In figure 1 is the feedback regenerative in nature and if yes can I apply virtual short to solve it.
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41 views

phase shift oscillator circuit

I'm planning to construct a phase shift oscillator circuit. I simulated it using multisim and i got the sine wave with values I wanned (you can check the pic). then i assembled the circuit on a ...
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52 views

TTL square wave inverter adjustable duty cycle

I am an amateur and I don't have experience with logic circuits so please forgive me if this is very simple. I have a 5V TTL crystal oscillator (4-pin). I need to create a second square wave from it ...
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32 views

STM32F405 Internal vs External Oscillator

If the frequency stability over a temperature range is not a concern in a project instead it's reliability in continuous long time operation is a more important factor then which of the two ...
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68 views

How the frequency of oscillation is determined in a multi-resonance oscillator circuit?

If we have a self-oscillator with multiple resonant frequencies, what are the criteria for the preferred frequency of oscillation? For example, a push-pull oscillator with parallel-compensated two ...