# Tagged Questions

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6k views

### Measuring 0 - 1MHz ( 0.25Hz resolution) Squarewave using an MCU

I need to measure the frequency of square-wave that can vary between 0 and 1MHz, and has a resolution of 0.25Hz. I havent decided on which controller yet but It will most likely be one of the 20pin ...
49 views

### Frequency-To-Voltage Convertor With LM2917

I'm trying to make a frequency-to-voltage converter by using LM2917. Its datasheet is very old and it doesn't explain function of the IC well. It just gives several example circuits and a formula for ...
94 views

### Finding frequency of a three-phase generator from phase voltages

I'm trying to find frequency (i.e.; rotations per second) of a balanced three phase generator. Output peak voltage of the generator goes up to 150V. One solution I found is to attenuate rectified and ...
66 views

### IC for pulse frequency

I'm trying to get RPM from spark pulses ranging from 100-40k pulses per minute. Currently I use a counter to reduce total pulses and then measure the time between rises and convert that to RPM. Is ...
590 views

### Counting DC power pulses per minute

I need to implement a frequency counter (pulses per minute) of a DC circuit that goes up to 20 volts. A little background, I am building a linear power supply 0-20 volts, 0-3 amps for my relative who ...
110 views

### 555 timer monostable time constants

When making an monostable circuit with a 555 timber, the time that pin 3 is on is calculated using this: time on = 1.1 x R1 x C1 My question is why is 1.1 included.
118 views

### 555 timer astable time constants

When making an astable circuit with a 555 timber, the frequency of pin 3s pulse is calculated using this: f = 1.44 / (R1 + 2R2) x C My question is why is 1.44 included.
291 views

### How can i know the frequency range of electronic device?

How do I know the frequency of an electronic device? For example, we all know that the microwave is working under 2.4 GHz frequency. So, if I want to know the other frequency range for other devices, ...
468 views

### AVR Measuring frequency using external interrupt - where are my cycles going?

I'm using an external interrupt to measure the frequency of a signal, the AVR clock is at 8MHz. I'm essentially counting the ticks between pin toggles using a 16 bit timer (with some handling for ...
717 views

### Frequency measurement with STM32

This question is mainly a query for an advice. I am trying to implement a frequency meter on STM32F4. Up to this point I have a working ADC converter with DMA and a timer which checks for the current ...
112 views

### How can I improve my Freq to Voltage circuit?

I had a term project which was based around Analog-to-Digital convertors. We used anLM2907 Freq-toVoltage convertor to take a 150mVpp sine wave (0- 1kHz) and convert that to a voltage. The voltage ...
377 views

### Estimating a sinc period and width of a rectangular pulse

For a rectangular pulse that has as a fourier transform of a sinc function like so: How can I estimate its sinc period in the frequency domain and compute the width of the rectangular pulse in the ...
575 views

### Frequency to voltage converters [closed]

I'm looking for a frequency to voltage converter IC that can operate with an input frequency of around 500 kHz. The device does not have to be high-precision and the operating voltage can be anything. ...
420 views

### How to observe powerline modulated signal?

I was assigned to observe the modulated signal of a PLC modem, but I have not really started yet. How do I do this? Should I use an oscilloscope or spectrum analyzer? If so, do I just connect it to ...
1k views

### Measuring frequency of a signal above 5V with a microcontroller

I want to measure the frequency (up to 300 Hz) of a rectangle signal, that varies between 0V and Vtop, where Vtop is anything between 5V and 15V. Because I cannot apply more than 5V to the ...
284 views

### counter giving erratic results for frequency measurement using Atmega32

I am using a photosensor which gives output as a square wave. The frequency of this square wave is being measured using Atmega32A with 1MHz clock. The full scale output of sensor is 500kHz. The ...
138 views

### power supply frequency response

I have a question regarding the frequency response of a boost converter. I am curious to know what causes the "blip" at around 8kHz that causes the response to go up and then back down. At first, I ...
252 views

### output filters for power supply design

I am trying to develop a design for a power supply design. At the output of my design is a diode rectifier with capacitive filter output. I've been told that I should expect to see an ESR zero or ...
2k views

### Problem with a Relaxation Oscillator (using Op Amp)

I'm studying a relaxation oscillator. This wikipedia circuit shows exactly my circuit with the only difference that I'm using different values for each resistor. I called resistor R the one ...
260 views

### Analog Telephone Frequency Response Curve

Old analog telephone circuits using carbon microphones seem to be said to have a frequency response of, from various low frequencies which differing reports put at between 275 Hz and 400 Hz, up to ...
2k views

### How to measure pulse width of an IR signal using an 8-bit PIC?

My friend and I want to design a universal learning remote controller, like this one, for learning purposes. What we want to do basically is store and replay infrared pulses. We want to detect 36kHz, ...
129 views

### Testing Oscillator Over Temperature

I want to characterize the frequency inaccuracy of several silicon oscillators over temperature to see which one will work best in my end application. If I populate the oscillator on a bare-board and ...
2k views

### How to correctly simulate a simple LM2907 circuit in LTSpice?

I'm trying to convert the frequency of a 0-5V square wave, which ranges from 0-20kHz, to a voltage using a simple LM2907 (8 pin) circuit. Using R1 as 100k, I've calculated C1 to be 416pF for a ...
441 views

### Measuring Frequency Shift

A previous question on doppler shift velocity sensor make me ask this question. @Chris_stattron provided an insight but I was too curious to leave it at that comment hence the question. Assume, I am ...