ba0sh1.com reverse engineered a cheap LED voltmeter he bought from Taobao and made it run on a I2C bus. He writes:
I’m planning to build a EEVblog-ish constant dummy load for battery and power supply testing. Dave in his build used a LCD voltmeter for the display. In the senseless pursuit of difference, I tried other display solutions including character LCD, graphics LCD, OLED, TFT, AMOLED, IPS, which resulted in several previous blogs but nothing ends up to be satisfactory. Along with the complexity grows exponentially from one solution to another, I slowly start to feel the importance of KISS concept, keep it simple stupid. All I need is just a number display, nothing fancy, nothing pricey, nothing takes my attention away from the analog circuitry. I decided to go back to the basic 7-segment LED display. “Simplicity is the ultimate sophistication”, how elegant it is!
Hacking a cheap LED voltmeter - [Link]
john @ circuitstoday.com writes:
The circuit given here is of a very useful and accurate digital voltmeter with LED display using the ICL7107 from Intersil. The ICL7107 is a high performance, low power, 3.5 digit analog to digital converter. The IC includes internal circuitry for seven segment decoders, display drivers, reference voltage source and a clock. The power dissipation is less than 10mW and the display stability is very high.
Digital voltmeter using ICL7107 - [Link]
A little known feature of Arduinos and many other AVR chips is the ability to measure the internal 1.1 volt reference. This feature can be exploited to improve the accuracy of the Arduino function – analogRead() when using the default analog reference. It can also be used to measure the Vcc supplied to the AVR chip, which provides a means of monitoring battery voltage without using a precious analog pin to do so.
Secret Arduino Voltmeter – Measure Battery Voltage - [Link]
Dual Voltmeter Ammeter 0-40 V / 0-4 A. Based on PIC 16F887
PIC Voltmeter – Ammeter - [Link]
The i-voltmeter is an electronic testing tool that can:
- Diagnose electronic functions of anything you need to test
- Data log electronic events over time
- Remote view events with your smart phone
- Create Remote Triggers
- Set Alarms
- Use as an anti-theft device
- Measure electrical voltage, current & resistance
Now you can test a full spectrum of electronics with the diagnosis and data logging features of the iV. Other units cost upwards to $1000. Because it is Bluetooth enabled, you can unleash yourself from the testing device with the iV.
i-voltmeter – Voltmeter with Bluetooth Technology - [Link]
Today I will show how to make digital bridge between Arduino and PC: control analog – digital converter and send measured data to PC. Windows application will be created using Visual C++ 2008 Express.
Voltmeter demo software is very simple, and here is a lot room for improvement, but I just wanted to show basics how to control com port and execute data exchange between PC and Arduino.
Digital voltmeter – Arduino and PC (Visual C++) – [Link]
Sergei Bezrukov writes:
This is a shortened translation from Russian of my article published in Радио (Radio) magazine, no. 8 (2010) pp. 21-23. The voltmeter is designed for controlling DC voltages at the output of a dual bipolar power supply. It not a universal instrument, since its input resistance does not exceed 40K, which might be too low for some measurements. However, it is perfectly fine for power supplies and does not noticeably load their output. The range of input voltages is 0 to 24V for positive supply and -24V to 0 for negative one.
The voltages are sampled every 300 msec and displayed on a 9-digit LED display. Only 8 digits are used, the middle digit slot is always off and serves a a separator between negative (on the left part of display) and positive (on the right one) readings. The unit provides a 0.01V resolution. For small negative voltages (not exceeding 10V in absolute value) a leading minus sign is displayed. For positive voltages a leading zero is suppressed.
Voltmeter for bipolar power supplies - [Link]
This is a simple application of internal 10-bit ADC (analog to digital converter) of PIC16F676 microcontroller.you can use this circuit to measure up to 30 v dc. the possible applications are on bench top power supply or as a panel meter in various system.
MICROCHIP’S PIC16F676 is the heart and brain of this circuit .the internal adc of the mcu with a resistor network voltage divider is used to measure the input voltage . then 3 digest of comm anode 7 segment display is used to display final converted voltage. as you can see in the schematic the displays are multiplexed with each other . means we switch on one display and put the corresponding digit on this while other two displays are off this cycle go for each of the display.
Panel Voltmeter Using PIC16F676 - [Link]
This is a simple application of internal 10-bit ADC (analog to digital converter) of MSP430G2231 microcontroller.you can use this circuit to measure up to 30 Vdc. the possible applications are on bench top power supply or as a panel meter in various system.
TEXAS INSTRUMENTS MSP430G2231 is the heart and brain of this circuit .the internal adc of the mcu with a resistor network voltage divider is used to measure the input voltage . then 3 digest of comm anode 7 segment display is used to display final converted voltage. as you can see in the schematic the displays are multiplexed with each other . means we switch on one display and put the corresponding digit on this while other two displays are off this cycle go for each of the display.
MSP430 based 30V voltmeter - [Link]
A couple of weeks ago I spent some time examining a fairly complex circuit board from my old, but still functional, clock radio/CD player. I was using the probe of my handheld multimeter to measure voltages at various IC pins and circuit traces. At one point during the process I thought, “Gee, wouldn’t it be nice if I had someone here to read the voltmeter to me as I test various points? That way I could focus on my probe and not accidentally short neighboring pins.” But then I realized that I did have someone to do just that: Microsoft Sam. I present to you the NI LabVIEW talking voltmeter:
LabVIEW: The Simple Talking Voltmeter - [Link]