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

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56 views

blinker circuit theory

simulate this circuit – Schematic created using CircuitLab A simple light bulb blinker circuit.......R4 is the bulb..I'm pretty sure I understand the functionality here. C1 initially ...
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48 views

Hartley Oscillator Alternate Oscillation Mode

I've been trying to build a hartley oscillator and have almost succeeded, however my calculations are off by appx 1000 relative to the measured waveform. AND the kicker is that it only works when I ...
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34 views

Colpitts vs. Hartley?

What are the pros and cons of using a Colpitts or a Hartley configuration for an oscillator?I know that the difference between them is the form of feedback, but does one or the other perform better ...
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42 views

Superheterodyne receiver with voltage controlled oscillator

I'm new in electronics and I want to create a FM receiver that performs a product of the received RF signal and a local signal (the local signal is also frequency modulated with a Voltage Controlled ...
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1answer
51 views

How to increase power of a wireless power transmitter circuit?

I designed this circuit for a frequency of 2MHz, but I get an output of 7mW. I need to increase the output power up to at least 10 to 20W. Help me to redesign the circuit. Consider the transformer ...
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53 views

Understanding a simple crystal oscillator transmitter circuit

I've recently built this circuit: http://makerf.com/posts/mighty_simple_shortwave_transmitter It works on the desired frequency as you can see from this video : ...
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2answers
106 views

What makes a crystal oscillation to begin

I'm trying to understand how the Pierce oscillator works. I started from the very beginning and I'm looking into the crystal resonator. Thanks to this answer How does a Crystal work? I've managed to ...
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27 views

asymmetric oscillator layout

Due to space and redesign time concerns, the crystal I'm using cannot rotate. I'm updating the circuit to hopefully make the clock as robust as possible. I have copper keepout in the dotted area ...
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70 views

Can any one give reason for this configuration of oscillator

Please give reason why this is is Common-Base configuration with Base feedback.
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4answers
86 views

How do crystal oscillators work with feedback consisting of CMOS inverters?

For a crystal oscillator to work, there must exist a feedback path with properly designed specifications in order for all to work as expected. Broadly, the basic form of this control system is as ...
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41 views

Why would the Schmitt trigger relaxation oscillator a bit unstable?

This thing oscillates from time to time. Why? (Respect part numbers, all chips from NXP) simulate this circuit – Schematic created using CircuitLab ...
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30 views

confused about behavior of relaxation oscillator

I'm just starting to learn about electronics by working through Charles Platt's Make: Electronics book and I'm on experiment 14, which is a relaxation oscillator for an LED. I should note that in the ...
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67 views

Why there is many configurations of Colpitts oscillator?

I would like to understand how colpitt's oscillator works but I'm confused because there are many configurations on the internet and I don't know what is the difference between them. For the next two ...
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48 views

about using clock chipset to generate square wave

I am looking for way to generate the square wave at 10MHz to 20MHz by an oscillator. After some searches, some one suggest the ECS 2200 to. I got few and have it tested. I am using 5VDC as power with ...
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85 views

square wave generator on 20MHz

I need a circuit that generates rectangular waves. It shouldn't be lo-hi-lo-hi, but a random sequence of lo-hi-hi-hi-lo-lo is needed. It also has to oscillate like that, at at least 20MHz. I don't ...
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1answer
71 views

ATmega162 fuses to select external clock 12Mhz?

Could anyone tell me how I could change the fuse bit, so that my ATmega162 uses 12 MHz external crystal. Once, I made the changes in the AVR fuses wrong the AVR went dead. That is why I need ...
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2answers
182 views

How does the negative feedback in this oscillator work?

EDIT: I don't think I'm using the term "negative feedback" correctly. What I meant is, how does the feedback that makes the closed loop gain equal to 1 work? I'm trying to understand the very basics ...
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1answer
62 views

maximum voltage that a colpit oscillator can withstand

I am working on a wireless power transfer project using, I need to design an oscillator. I need a frequency of over 2MHz and I need it for a high power application. So my question is what is the ...
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69 views

Can one always drive oscillator inputs with a single-pin oscillator output and bypass the integrated feedback circuitry?

Very little is written in the MCP2211 datasheet regarding the oscillator input configurations. The microcontrollers I have been using lately allow you to use the self-powered, single output ...
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122 views

LC Oscillator, Tank Circuit

How does a tank circuit work with a dc power supply? I understand that if you charge a capacitor that's in parallel with an inductor and then remove the power supply then the capacitor and inductor ...
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3answers
97 views

Slightly weird astable oscillator in a 555, where does this capacitor discharge to?

In the 555 datasheet, the cap is usually connected to pin 7 (discharge), but in this circuit, it's not: When the capacitor voltage is >2/3Vcc, output will turn off and current will have no where to ...
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3answers
191 views

What is the wrong with this simple sine wave generator circuit?

I've designed this circuit myself aiming to generate sine wave at the collector of the transistor, but I doesn't work. the current at the collector is DC. Is it a simulator error or the design is ...
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1answer
48 views

Need help with Relaxation Oscillator with Parasitic Capacitance

I am trying to build a capacitance meter using a simple relaxation oscillator with a fixed resistor R in series with a capacitor to be measured C. I am applying the formula where Freq=frequency and K ...
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1answer
293 views

PIC18F4550 External Oscillator

I am currently trying to get the configuration bits set up to blink a LED with a 20MHz external crystal. It is operating correctly using the internal oscillator, but does nothing with the crystal, and ...
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3answers
57 views

Simple switching between clocks using oscillator disable pins

I am working on a circuit where I need to use different clock sources. I am using two HCMOS oscillators. Both oscillators have an disable pin. When disabled, the clock output buffer is placed in ...
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46 views

Question about an LC oscillator

I saw a previous question about an LC oscillator and I wanted to know how it works. What I figured out is, that the current across R2 is approximately always constant (Q1 base current doesn't drop too ...
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2answers
89 views

PIC24 Primary Oscillator XT_PLL frequency is off by 3 percent

I am using a PIC24. After solving the issue with the PLL (PIC24 PLL module is always out of lock) I am struggling with large variation in the system frequency. I wrote a small code that is used to ...
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89 views

Is an LR Phase Shift Oscillator possible?

All the phase shift oscillators I've seen use RC stages each of which produces a 60degree phase-shift. Is it possible to inductors instead of resistors? My understanding is that inductors also cause a ...
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1answer
96 views

PIC24 PLL module is always out of lock

I have been working on a PIC24FJ128GA310 development board for for some time now and recently got a PCB made. If I try to move my code into the new board all timing related math and functions are ...
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1answer
134 views

Colpitts oscilator - purpose of voltage divider

I'm confused by the Colpitts oscillator shown below: I've marked my understanding of the various components, but I'm having trouble understanding the tank circuit. My understanding is that C1 and ...
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77 views

Colpitts Oscillator, purpose of capacitor

Today, I built a colpitts oscillator, using information from various sources I found online. The schematic is as follows: And a picture of the build and some waveforms are here. There are several ...
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1answer
77 views

How to generate Duty Cycle from DC without 555

I am currently working on a simple circuit which includes creating duty cycle from DC. Also, I need to change it's pulse width with time. I have decided to use op-amp relaxation oscillator to produce ...
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49 views

Tank circuit resonance sometimes 3x expected value

I've been reading about Tank circuits, and wanted to try and see if I could see the resonance on a scope. I used a 22nF capacitor and a 10uH inductor, I wrote my notes up here. Some of the time I saw ...
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31 views

Phase-shift oscillator (high pass configuration) why only 2 resistors to ground?

Today I built another phase-shift oscillator (you can see my full notes here). The circuit is based on those I've found online, and uses the capacitors in a high-pass configuration: The circuit ...
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31 views

phase-shift oscillator design decisions

I've been learning about phase-shift oscillators and put together this design: I built it and it seems to work pretty well, you can see the exact values I used, and design here: [1]. But the design ...
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50 views

Understanding astable multivibrators

I've been trying to understand the astable multivibrator shown above. Wikipedia has a pretty good description. But I've tried to write it up on my blog in my own words here: ...
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1answer
163 views

Trying to understand this oscillator… there's no emitter grounding or bias

I dissected and drew up this oscillator circuit from a cassette machine the other night. It's purpose is for biasing the tape. I'm curious though as to how this oscillator functions since the base is ...
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1answer
42 views

Attenuated Lower Envelope from Colpits Oscillator

Could someone explain to me why the output of this oscillator is the way it is? With a DC input of 6V (no small signal), I get an oscillation between -2V and 7V, which was unexpected. Is this due ...
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37 views

Amplify an electret microphone and feed the amplified signal through a piezoelectric disc?

I’m a student and Im trying to use an electret microphone to pick up an audio signal which is then reproduced by a piezoelectric disc as a part of an experiment with sound perception in spaces and ...
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1answer
129 views

PnP NpN transistor circuit, Were would the mic jack go?

I know the circuit says to put the mic jack parallel to the speaker, but im not exactly sure were to put it. Also, could I use another speaker as the mic? This is the pnp npn circuit I found on the ...
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1answer
97 views

Oscillator with CMOS inverter - calculate elements

I am trying to make 125 KHz oscillator based on CMOS inverter and feedback circuit consisting of Pi C-L-C section, as shown below. Since I need sine wave I will ommit the second inverter. Before ...
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103 views

Replacing Crystal Oscillator with DDS.

In a circuit like this, can the crystal oscillator be replaced with a DDS such as a AD9850? If so can it just be dropped in or would other components have to be changed? Second question, how ...
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102 views

Why doesn't this oscillator oscillate

According to the solution, it says it's because the phase shift is wrong. The gain network is non-inverting, so I assume that means that the LC feedback network was not 0 degrees for that particular ...
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4answers
403 views

Does this simple RF transmitter circuit actually work?

I've come across this circuit a few times while searching for simple transmitter circuits, and decided to try it. According to this site, it should be transmitting at around 90Mhz. ...
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111 views

I need helping understanding this VCO circuit

The two circuits of interest are described in pages 12-14 of Texas Instruments' Application Note 263, Sine Wave Generation Techniques PDF WARNING I'm primarily concerned about the circuit in Fig. 15, ...
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3answers
98 views

Unexpected resistor for oscillator

Please see these two part of this board : In your opinion, What's the usage of the R32 resistor? also in the AN2867 aplication note has been mentioned: Then we have to put a resistor to limit ...
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1answer
54 views

Inverting effect of resistance in an RC circuit

I have a question on basic electronics. I'm looking at a very simple CMOS RC Circuit around a Schmitt Inverter which creates square waves. Something like this. simulate this circuit – ...
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2answers
121 views

What's the frequency v power relationship of an oscillator + transmitter?

I'm starting with the assumption that a higher frequency EM wave is more energetic than a lower frequency one and thus requires more energy (and thus more power) to transmit. In my naive model of a ...
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1answer
105 views

crystal oscillator output

I have seen the crystal oscillator output in the oscilloscope and it looks something similar to a sine wave (at least nothing similar to a square wave and with a hard to calculate duty cycle)! So ...
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2answers
190 views

Simple Oscillator Designs

I want to be able to create simple oscillator circuits for clocking in digital circuits and am wondering what is the most simple design people know of? I could use a simple ring oscillator which is ...