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26 Mar 2011

Embedded-Lab.com has just posted a new project called “Multi-function power supply”. It is not just a simple power supply but it has built-in Volt-, Current-, and Frequency meters. The beauty of this project is that while you are prototyping your circuit, you can continuously monitor how much current your circuit draws at a specified operating voltage. This way you will know in advance how much power your design will require. The built-in frequency counter can measure frequencies up to 50.0 MHz.

DIY Multi-function power supply unit – [Link]


21 Mar 2011

This project (posted on hobbydebraj) describes a simple spectrum analyzer based on a dsPIC30F4011 microcontroller. It uses Microchip’s FFT library codes to calculate the frequency spectrum of an input signal. The signal conditioning is achieved by a TL084 Op-amp IC. The peaks of spectrum are displayed on a graphics LCD. [via]

A simple spectrum analyzer using dsPIC30F4011 – [Link]

14 Mar 2011

Scott writes:

This  Frequency Counter:

(a) works well into the RF range (I tested it to 50MHz and it was solid, unlike some of the posts here which stop working at a few hundred kHz)

(b) is extremely cheap (around $10),

(c) is portable, battery powered, and hand-held, and

(d) uses common components that are stocked at mouser.com so anyone build one! It’s based around an ATMega16 microcontroller reading frequency from a 74lv8154 dual 16-bit counter (acting as a 32 bit counter) and displays frequency on two multiplexed 3 character 7-segment displays.

$10 Frequency Counter – [Link]

9 Feb 2011

There are many ways to determine the capacitance of a capacitor. You can use an oscillating circuit where the capacitor is a part of it and measure the frequency of oscillation to find the capacitance. Or, you can also use a resistor-capacitor network and measure the rate of voltage rise across the capacitor to determine the capacitance, if the value of the resistor is known.

Here’s a similar project where a PIC16F88 microcontroller measures the time required by a capacitor to charge through a known resistor from 0 to half of the reference voltage provided, and the capacitance is determined based on that information. [via]

Determine capacitance by measuring the charging time – [Link]

5 Feb 2011

Measuring the frequency of a signal may seem to be a simple process of counting pulses, but in order to get better accuracy, few other things should be considered, such as the gating interval and the range of measurement. This tutorial, posted on the pcbheaven.com, briefly describes two typical methods of frequency measurement: Direct Frequency Measuring (DFM) and the Reverse Frequency Measuring (RFM), with their pros and cons. [via]

A brief tutorial on frequency measurements - [Link]

27 Jan 2011

electronics-diy.com writes:

This is 60 MHz frequency meter / counter for measuring frequency from 10 Hz to 60 MHz with 10 Hz resolution. It is a very useful bench test equipment for testing and finding out the frequency of various devices with unknown frequency such as oscillators, radio receivers, transmitters, function generators, crystals, etc.

10Hz – 60MHz Frequency Meter / Counter – [Link]

28 Dec 2010

This project is a frequency standard based on GPS signal that has the advantage of great stability.

Using the GPS Satellite system offers the advantage of very accurate timing and by extension, frequency control. The long term error is to all intents and purposes zero, with time and frequency accuracy being comparable to the international standard. The traditional route is to use a relatively low cost GPS receiver module which outputs a 1 Pulse per second signal (1 PPS) aligned to UTC.

GPS Disciplined Frequency Standard - [Link]

23 Dec 2010

This project is a DIY power meter made by Bill Porter and it is used to monitor the electricity usage of his home. The device is able to measure the power the house is using, the power factor, voltage and frequency. The data is transmitted wireless to a display unit. View construction details, schematics and board on the link below.  [via]

DIY power meter – [Link]

14 Dec 2010

This project shows how to build a Spectrophotometer using a toilet paper roll, duct tape and a graphing calculator. Light is shined through a sample solution, passes through a diffraction grating, then shows up as bands of color on the projection surface. The photosensor can slide back and forth along the spectrum to get readings at different frequencies using a multimeter. [via]

DIY Spectrophotometer - [Link]

26 Sep 2010

This tutorial shows how to use the Timer1 module inside PIC12F683 as an asynchronous counter to compute the frequency of an external clock source. The external clock is connected to the GP5/T1CKI port of PIC12F683 and the measured frequency value is sent to a PC through serial port to display on an hyperterminal window. A 555 Timer IC operating as an astable multivibrator is used as the external clock source. The Timer1 module is 16-bit so it can count up to 65535. If the Timer1 is turned ON for 1 sec, the maximum frequency it can measure is 65535 Hz. Any frequency higher than this will create Timer1 overflow. An interrupt service routine is also written to demonstrate how to detect the overflow and take appropriate action. This concept can be extended to measure higher range frequencies.

How to measure frequency of an external clock source using PIC - [Link]





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