Ben Eishen sent in this link. He says, “I have been thinking about building an ESR meter, and this one looks like a winner.” The design is based on the ATMega88 and according to the designer, Dr. Le Hung, “The LCFesR 4.0 unit is a precise, wide range meter that can measure inductivity, capacity, frequency and equivalent series resistance of a capacitor in-circuit, which can be easily built with homemade one- or double-faced PCB and available electronic components.” The video above shows the LCFesR measuring component values as compared to values determined by a commercial unit.
The schematic and documentation can be found on Dr. Le Hung’s website.
ATMega88 based LCFesR meter – [Link]
The Air Quality Egg is a sensor system designed to allow anyone to collect very high resolution readings of NO2 and CO concentrations outside of their home. These two gases are the most indicative elements related to urban air pollution that are sense-able by inexpensive, DIY sensors.
Air Quality Egg – [Link]
Build a circuit that displays four channels 0-100C using Pt100 as the temperature sensor. Wichit Sirichote writes:
The RTD or the Pt100 is one of the high accuracy temperature sensor for laboratory. Using the high resolution delta-sigma converter, enables designer to use a simple voltage divider circuit for measuring the resistance of the RTD without the need of any DC amplifications. This instrument shows how to use the LTC2420, 20-bit delta-sigma converter and the LM385 reference voltage for measuring four Pt100 sensors and displays on the text LCD.
4-Channel Pt100 Thermometer – [Link]
Build a generic instrument, the Digital Voltmeter using the classic DVM chip, the Intersil ICL7135 and the 8051 compatible microcontroller. Wichit Sirichote writes:
I got the idea to design the digital volt meter when I visited the scientific lab in school at Bangpain district. I thought the lab should provide the generic instrument that student can use it for many experiments. One of the generic instrument is a digital volt meter. For example, when students make a simple battery with lemon, they can measure the EMF and learn the different of using various kinds of electrode. So I got back to 1982, when I was a university student, I do remember the Intersil ICL7135 very clearly. This year 2011, almost 29 Years, the classic integrating type analog to digital converter is still interested. With a cheap price and easy interfacing, I think I will design a cheap digital volt meter with microcontroller to provide serial interface similar to the Fluke45. Two channels is good for scientific experiment. The serial port RS232 is also nice for interfacing to the PC. Let us see the prototype of the meter in Figure 1. The display for each channel is 8-digit 7-segment LED. It is cheap and very reliable.
Dual Channel Digital Volt Meter – [Link]
Raj from Embedded Lab describes in his latest tutorial the theory of a very basic digital capacitance meter and its implementation using a PIC microcontroller. It is based on the principle of charging a capacitor through a series resistor and determine the time required to charge it to a known voltage. The built-in analog comparator and Timer2 modules are used in this process. The meter can measure capacitance from 1nF to 99.99 uF.
Digital Capacitance Meter using a PIC Microcontroller – [Link]
The 2200 series combines an oscilloscope, spectrum analyser and arbitrary wave form generator in a compact but powerful PC instrument. Now the series is being extended to include three new models 2206, 2207 and 2208. The new models have increased bandwidth, higher sampling speeds, bigger buffer memories and external triggers. [via]
PicoScope 2200 Entry Level USB oscilloscope – [Link]
Ivan Sergeev writes:
The Wireless Power Meter is a simplistic ATmega88p and ZigBee/XBee based true V-I power meter. AC voltage measurement is made from the rectified signal of a step-down transformer, and current measurement is made with the pass-through Allegro ACS712 Hall-Effect sensor.
Wireless Power Meter – [Link]
Zener diode is a special diode, unlike normal diodes zener diodes are intended to work in the breakdown voltage. These components maintain constant voltage at its terminals. This is a circuit to help you find out what’s the breakdown voltage of your diodes.
- Read Vz value of zener diode in Led display
- Zener diode tester range: 1V to 50V
- Two scales 5mA and 15mA test
Zener diode tester 1V to 50V – [Link]
Steve @ semifluid.com writes:
Using the PIC18F2550 GLCD Text Test as a basis for further experimentation, I put together a simple and accurate graphical oscilloscope using a PIC18F2550 microcontroller and a AGM1264F graphical LCD. The oscilloscope measures the average voltage, the maximum voltage, the minimum voltage, the peak-to-peak voltage, and the zero-crossing frequency for a DC signal over 100 samples. The oscilloscope has a built in edge trigger function that can be set to capture on rise or fall (or disabled altogether). The time scale for the display is variable and can be easily redefined using the changeTimeDivision function. Likewise, the voltage range can be change to 0-5V, 0-2.5V, and 0-1.25V. The main limitations of this oscilloscope include relatively slow acquisition time and sampling rate (~60kHz) and the fact that the inputs are limited by the constraints of the internal ADC. However, it is a very nice display and I highly suggest you view the videos to see it in action.
PIC18F2550 KS0108 Graphical LCD Oscilloscope – [Link]