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

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70 views

How does the negative feedback in this oscillator work?

I'm trying to understand the very basics of oscillators and I came across this article (if the page is down, go here (page 3)). Here is the circuit: As I understand it, there is a positive feedback ...
0
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1answer
54 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 ...
0
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2answers
54 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 ...
0
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2answers
96 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 ...
0
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3answers
81 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 ...
3
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3answers
165 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 ...
0
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1answer
40 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 ...
4
votes
1answer
162 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 ...
0
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3answers
54 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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0answers
44 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 ...
0
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2answers
76 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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2answers
73 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
87 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
115 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 ...
0
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0answers
65 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 ...
0
votes
1answer
71 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 ...
0
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0answers
46 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 ...
0
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2answers
27 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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2answers
24 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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2answers
47 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
150 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 ...
0
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1answer
41 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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0answers
31 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 ...
0
votes
1answer
103 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 ...
0
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1answer
80 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 ...
3
votes
2answers
91 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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2answers
100 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 ...
3
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2answers
288 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. ...
0
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1answer
96 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
92 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 ...
0
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1answer
47 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 – ...
0
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2answers
116 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 ...
0
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1answer
99 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 ...
4
votes
2answers
176 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 ...
3
votes
1answer
331 views

Crystal Oscillator not giving correct frequency

I have a 48MHz Crystal Oscillator (see here) that I am using as a clock for my microcontroller (EFM32GG332F1024). Looking at the datasheet for this crystal it seemed to me that the load capacitance is ...
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2answers
104 views

Troubleshooting circuit in make Electronics Book (Experiment 8) [closed]

I created the same circuit as in Experiment 8 of make Electronics book but cannot get it to work in the same way as described in the experiment. When I connect the circuit to the power source and ...
-1
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1answer
49 views

analysis square waves oscillator: how do I calculate the values?

Which are the Vc (V+) and V-, I's and Vout values in these circuits? The node i's and the Vc and Ic?
0
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1answer
55 views

Error: Model in Pspice is undefined

When I simulate the circuit below in Pspice, the output info says: model J2n5485 used by Q2N5485 is undefined. But I have defined the model in the code. I need to ...
0
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2answers
123 views

Why does the tank circuit of Coplitts oscillator produce 180 phase shift?

http://www.circuitstoday.com/colpitts-oscillator I would like to understand how Coplitts oscillator works. This link says that the tank circuit of Coplitts oscillator produces 180 degrees phase ...
2
votes
1answer
94 views

PIC18 not working when wiring 30pf capacitors of cristal resonator to ground

I'm using pic18 with external oscillator 16MHZ 16M HZ HC-49S Crystal Oscillator with two 30PF capacitors configuration OSC = HS using breadboard, when wiring the ...
1
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2answers
153 views

Need help understanding simple oscillator circuit

I know this seems like a really basic question, but bear with me. The following circuit diagram is given by one of my old electronics kits: simulate this circuit – Schematic created using ...
0
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1answer
131 views

Transistor amplifier circuit for triangular wave

I've made triangular wave oscilator as shown in Fig. 1 and it works perfectly at frequancy 10 kHz with peak voltage +3 Volt to -3 Volt. I intend to generate SPWM. But when I feed this circuit to ...
1
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1answer
113 views

Value for feedback resistor in pierce crystal oscillator configuration

This question is partially an "understanding english" question and partially and "understanding the pierce oscillator configuration" question. Backstory I'm currently looking at using a Freescale ...
-1
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1answer
117 views

How to design a 500 khz sine wave generator? [closed]

I need to design a 500 khz sine wave generator. Could anyone help?
0
votes
1answer
81 views

How could this GPIO-controlled LED status blinker be improved?

I'm building a simple circuit to drive an LED status indicator in a project built around a RPi. The circuit takes its power from the same source as the RPi and is connected to one of the RPi GPIO ...
-1
votes
2answers
79 views

can LC tank circuit alone produce oscillations? [closed]

Circuit below is the hartely oscillator circuit, I simulated it in multisim to know how exactly oscillations occurs, while doing so I just seperated tank circuit (from tansistor base and collector ...
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0answers
79 views

Oscilllator model in multisim

What's wrong with this schematic? Multisim doesn't generate oscillation. Also I changed R3=1000, R3=500 but all the same.
1
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1answer
81 views

Why does this circuit oscillate and produce sound?

I've connected an 8-ohm speaker in series with coil. When I apply 5 volts / 500 mA to the combination (coil and speaker), I heard a very high frequency sound (something like whistling). The coil is ...
0
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0answers
45 views

Can I replace crystal input with mems oscillator

I am designing a device that uses a real time clock (RTC) from ABRACON. AB1805-T3. RTC Datasheet: http://www.mouser.com/ds/2/3/AB18XX-30381.pdf The device has the option to either select an internal ...
3
votes
1answer
250 views

PIC16F628A Blinking LED

I was setting up a PIC16F628A for a simple Hello World program (blinking LED) and somewhere in the process, I have failed. The LED stays lit at the specified pin and does not "blink". I am using the ...