Small portable DIY illuminance meter

Lux meters are common devices among photographs or lighting specialists  – anywhere where illumination level is important parameter. Following lux meter developed by Sergei is capable of measuring illuminance in the range 0.025 – 99999 lux. He used MAX44007 sensor which is already factory calibrated. He’s chosen a C8051F304 microcontroller from Silicon Laboratories. It talks to lux sensor via I2C interface and also updates 128×32 graphical LCD. Lux meter is only a 30x60mm size and is powered by single CR3032 coin cell. Continue reading

Temperature sensor with LCD

This is an 8051 based project with AT89C51AC2 microcontroller that reads temperature sensor LM35 value and displays it on standard LCD screen. As LM35 scale factor is 10mV per 1ºC there is a fixed gain amplifier used that pulls the voltage to 2.5V (VREF=2.5V) limit for 100ºC instead of 1V. This gives better accuracy of readings. Code is written in C and ASM languages – this gives quite some clue of working internals. Project is nicely documented and put in to Google doc. Continue reading

Thermistor based thermometer

This thermometer doesn’t use any fancy digital temperature sensors – it is based on NTC thermistor which resistance depends on ambient temperature. Design is based on Atmel89S52 microcontroller which drives four 7 segment LED displays and reads temperature value via external 12-bit ADC (LTC1298). ADC values are read through SPI interface. Reading accuracy is about 0.1ºC accuracy. Continue reading

Yet another meter clock

It seems that meter clocks gained some popularity among hobbyists. Probably because it’s a bit challenging and great looking projects. This one is based on AT89C5051 microcontroller. Circuit is pretty simple where timing is counted by DS1307 chip and analog meters are controlled by sending voltage levels through DAC converters and amp buffers. Clock is graded to 24 hour scale and can show hours, minutes and seconds on three meters. To see more packaging examples follow here. Continue reading

Digital Thermometer powered by AT89S52 microcontroller

8051 microcontrollers are mature microcontrollers that have been used for quite long time and they still are popular in many applications. So here it is a standard temperature sensor project which has some educational aspects. As you know AT89S52 microcontroller has no ADC interface so there is an external ADC used which is built from scratch. In few words it is a counting type ADC which is based on DAC where digital to analog conversion is continued until match is found with comparator. So building such device is more fun. In this project a NTC type thermal resistor is used which value is red by custom ADC and value is displayed on 3 digit 7 segment LED indicator which is also driven dynamically. So again this is simple interesting and… Continue reading

The Data Acquisition and Logging System Based on AT89C51

Do you ever get involved with the data acquisition and logging system? For those that have didn’t familiar with the data acquisition and logging system, it is a device that has been specially designed to measure and log some parameters. The main purpose of the data acquisition system is analysis the logged data and improves the object of measurements. Most of the data acquisition and logging system is electronic based, where it can be made of hardware, software or both of them. Let’s pay your attention on this project. The data acquisition and logging system is based on AT89C51, where it’s a microcontroller project log the temperature system. It can be used to monitor and control environment temperature. The things should know about this project is although it’s controlled by… Continue reading