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Questions tagged [oscillator]

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

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1answer
18 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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0answers
30 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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0answers
44 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 ...
5
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1answer
85 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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2answers
43 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
50 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
62 views

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
136 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
47 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 ...
2
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2answers
52 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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1answer
50 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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3answers
104 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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2answers
398 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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3answers
85 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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2answers
82 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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0answers
39 views

TL064 CN issue (Phase shift oscillator)

as part of my project to construct an electrical conductivity. I have an oscillator circuit in my design. The one I chose to go for is a phase shift. in the picture you can see my circuit which Pin ...
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0answers
38 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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3answers
44 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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1answer
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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2answers
67 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 ...
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0answers
45 views

How to place parts crystal oscillator in DipTrace

I'm now into DipTrace and getting used to it. I placed parts by placing parts' standard like QFN-32, ESP8266EX etc... but I'cant find the way how to place a crystal oscillator. This is the one that ...
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2answers
47 views

STM32F407 fallback to Internal Osc

I wonder if it is possible at run time to detect that an external Oscillator has gone bad and the application now falls back to internal Oscillator.. specially for the case of STM32F407 MCU?
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1answer
55 views

Adjusting duty cycle without affecting frequency of a VCO

I've looked around the internet for a simple voltage controlled oscillator that is able to produce various waveforms in phase with one another. I asked about it in this site and was directed to a dual ...
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3answers
80 views

74HC4060 lower frequency limit

I need to sequence some micropower (low-microamp range) logic at a once-per-several-minute rate, and am falling back on the good ol' 4060 as my timebase (plus a 138 and a 534 for the sequencing). I ...
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2answers
104 views

Testing crystal oscillator with multimeter crashes system

I have an old XT computer with a crystal oscillator that I would like to test. My multimeter has a Mhz setting that as far as I know should allow me to test it. (Providing the crystal is powered) ...
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1answer
118 views

Is it the crystal / quartz?

I have a simple gadget (called "Fridgezoo") that talks when the fridge stays open. I always hated it, but my sentiments are with it (hey, it talks!) so I want to repair it. What's the problem? It ...
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0answers
64 views

Sawtooth oscillations in bidirectional bus splitter [duplicate]

I am trying to listen in on a SPI-like protocol which is transferred on one busline in both directions (no slave-select). To discriminate which data is sent by which side, I need a bus splitter that ...
49
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5answers
6k views

Why does music synthesizer built from chain of astable multivibrator circuits get “out-of-tune” after a few hours?

I built a prototype keyboard/sound synthesizer using a chain of 13 astable multivibrator circuits whose outputs are connected to an audio amplifier chip (LM386) and speaker, all powered off a 9V DC ...
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0answers
99 views

How can I get this circuit to “make noise”

I designed this noise generator circuit that uses a 1N514 Schottky diode with a VDB transistor amplifier(note: the upper VDB resistor is actually 15kOhm). Looking at the oscilloscope trace it seems to ...
3
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2answers
251 views

How do crystal oscillators start?

I have read the answers to the question,"How do crystal oscillator start to work" in this forum. And the common answer which I got is that, there are many frequency around the crystal. The crystal ...
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1answer
56 views

JFET colpitts oscillator - very unstable

I've designed, simulated and build this simple JFET colpitts oscillator and I couldn't get it to work with real parts. I didn't have BF256B jfet model so I simulated it using some generic one. The ...
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1answer
44 views

High and Low times for 555 oscilator are inverted

I’m new to electrical engineering and this is my first time working with an oscillator. I'm trying to setup a 555 timer ic as an oscillator with a low time of 1s and a high time of 0.5s. I've been ...
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2answers
60 views

BJT Astable Multivibrator - What is the max. oscillation frequency?

What is the max. oscillation frequency of this Astable Multivibrator circuit? Is it directly related to transition frequency of the transistor? I plan on using it with BC547B transistor. The hardwired ...
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5answers
169 views

Transformer Outputs Voltage High Above Expected Voltage

I have recently put together this circuit, which works basically as expected. Due to my lack of certain parts, however, I had to replace the 68 Ohm resistor with a 52 Ohm resistor, and the MOSFET I'...
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2answers
84 views

Colpitts values for NXP's SA605?

I'm trying to put together a simple superhet radio, receiving at 161.75MHz (this is for AIS reception.) I've been trying to design around NXP's SA605 chip (see SA605) but I'm having a hard time ...
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4answers
131 views

How to radiate a positive oscillating voltage?

I am trying to build a simple AM transmitter, transmitting only a carrier wave and thus silencing the noise on my radio standing next to my circuit. I built this circuit on a breadboard. It's a ...
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1answer
29 views

NMOS limiting circuit for Colpitts oscillator

According to my book, the amplitude of the output sine wave produced by the following Colpitts oscillator should be limited by transistors M1 and M2. We only get a final answer without reasoning and ...
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3answers
1k views

What is meant by 'local' in local oscillator?

We know that a local oscillator (LO) is an electronic oscillator used with a mixer to change the frequency of a signal. But what do we mean by 'local'? How is 'local oscillator' different from ...
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4answers
97 views

Can’t reproduce oscillations using a simple inductor capacitor circuit?

I’m trying to reproduce a simple oscillator conductor / inductor circuit as shown here. I replicated exactly the same scheme on a breadboard and check all the connections using a led However when ...
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1answer
71 views

Vary the Vpp of sinusoidal oscillator

For an assignment I have to create a sinusoidal oscillator with 5 Vpp (centered around 0 V) oscillating at 10.0 kHz. The oscillator works as expected, at the right frequency, but the voltage needs to ...
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3answers
109 views

crystal oscillator Application

(Note: I am aware that crystal and oscillators are two different things but a lot of people use them interchangeably so I am using it in the title.) My question is about Oscillators, all oscillator ...
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1answer
43 views

Can I use the oscillation frequency equation for this circuit?

I'm not really sure if this is a question that can be answered so I'm sorry in advance if it isn't. I've just started doing electronics on a breadboard and I'm making a "Mini Strobe Light" from Jaycar'...
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2answers
56 views

Low-impedance tap in this oscillator circuit

Here is the schematic of Michigan Mighty Mite, a popular transmitter circuit design. It seems to be quite close to a regular feedback oscillator, with a few peculiarities. What puzzles me is the ...
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0answers
30 views

MOSFET Switch for Tuned LC Tank

I am trying to implement the circuit as shown below. I essentially want to be able to control the gate voltage of the NMOS to change the resonant frequency from 5GHz to 2.5GHz. For a transistor size ...
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1answer
47 views

Link between phase noise and linewidth for a oscillator?

I was googling for a formula to transform the dbc/Hz value given in data sheets for VNA, spectrum analyzers and VCO is often given in dBc/Hz with offset. Now looking up research papers about future ...
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1answer
107 views

Crystal oscillator replaced with exact frequency for clock?

I'm repairing my Nintendo Donkey Kong arcade PCB and I have no pulse when tested with my logic probe. I found out that the crystal oscillator (2 pin HC-18U) was not connected to the board, since the ...
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1answer
66 views

Single supply opamp colpitts oscillator

I'm designing a Colpitts oscillator with a single supply rail-to-rail opamp powered with 3.3 V. The positive input of the opamp is set to VDD/2 to offset the negative part of the oscillations so ...
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2answers
61 views

Can I use MCU's internal oscillator when communicating with GPS and cellular modules?

Can I use MCU's internal oscillator when communicating with GPS and cellular modules? I want to avoid connecting external crystals for the MCU since they generate noise, extra components, extra costs, ...
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4answers
164 views

Confusing quartz crystal impedance graphs

I thought that at the series resonant frequency of a piezoelectric oscillator the impedance of the crystal would be the lowest, and at the parallel resonant frequency the impedance would be the ...
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3answers
137 views

What actually is the load capacitance of a quartz crystal?

I'm having hard time understanding the principles of piezoelectric crystal oscillators. I've found this picture: I understand that "load capacitance" is something you have to connect to a crystal. I ...