This project is a Low Ohm meter able to measure 0.001 up to 1.999 Ohm with a “Direct Resistance Readout in Ohms”.
You must use two separate batteries. One for the DMM and one to supply power to the LM317LZ. I recommend the LM317LZ, which is the 100 mA, T0-92 version of the normal LM317. But you can also use the LM317, in the T0-220 package, if you want. The trimpot must be set precisely to deliver 100.0 mA out to get truly accurate resistance measurements. So you need a very accurate Milli-Amp Meter to adjust this Correctly.
Low Ohm Meter – Measures 0.001 up to 1.999 Ohm – [Link]
This is a temperature and humidity sensor with serial output that can be read with a computer. An LCD display could be used with minor modification. The unit is based on Atmega8 microcontroller. It uses LM335AZ temperature sensor attached to AVR ADC port and NONEYWELL HCH-1000-002 humidity sensor. [via]
Temperature and humidity sensor with serial output - [Link]
When teamed up with an oscilloscope, this simple circuit provides a means of measuring capacitor ESR. A 555 timer (IC1) configured as a 2.3kHz free-running oscillator acts as the timebase. It provides narrow (7.7µs) pulses to the capacitor under test via a NAND Schmitt trigger (IC2) and transistor Q1. A 100Ω resistor in series with Q1 limits current flow to about 50mA. Therefore, an ESR of 1Ω will produce pulses across the test capacitor of 50mV, which means that an oscilloscope with a vertical sensitivity of 5mV can measure ESR down to 0.1Ω or less.
Oscilloscope ESR Tester - [Link]
A typical capacitor checker measures the capacity (usually in micro farads) of the test capacitor. Some advanced units also test for leakage current. Most of these testers require that the capacitor be removed from the circuit. Unless the capacitor has totally failed, they will not detect a high ESR value. In a typical circuit, there may be 10′s or 100′s of capacitors. Having to remove each one for testing is very tedious and there is a great risk of damaging circuit boards. This tester uses a low voltage ( 250mv ) high frequency (150khz) A/C current to read the ESR of a capacitor in the circuit.
Capacitor ESR Meter – [Link]
Simon Inns builds this realtime PIC based audio spectrum analyzer. The analyzer uses Fast Fourier Transform routine written in C to run as efficient as possible on the 8 bit PIC18F4550 mcu. The output from the FFT is displayed using a 128×64 graphical LCD to allow a real-time view of an audio signal. [via]
PIC spectrum analyzer uses Fast Fourier Transform routine – [Link]
This project is a temperature controlled FAN based on LM311 IC. The fan is activated only when it is necessary. Working temperatures are 0C to 150C.
Temperature control circuit – [Link]
This project is a digital voltmeter based on 16F88 microcontroller, a 7 segment 3 digit display and some resistors.
Digital Voltmeter – [Link]
This project shows how to make a tweeter enabled power meter. “adafruit” used an existing Kill-a-watt power monitor.
My plan is to have each room connected to a 6-outlet power strip which powers all the devices in that room (each kill-a-watt can measure up to 15A, or about 1800W, which is plenty!). That way I can track room-by-room usage, for example “kitchen”, “bedroom”, “workbench”, and “office”.
Tweet-a-watt: a twittering power meter – [Link]
This project shows how to build an ESR (equivalent series resistor) meter using common available components. ESR meter measures the equivalent series resistance of the capacitor, almost independently of its capacitance, so you can easily determinate if a capacitor is damaged or not.
An Equivalent Series Resistance Meter – [Link]