This instructable shows how to build a photovoltaic cell curve tracer using Arduino and OPA549S OPAMPS.
This projects shows how to create an IV (Current and Voltage) Tracer that can be used to teach the electrical characteristics of a solar panel.
This project was created as part of an Electrical and Computer Engineering capstone project at The Ohio State University.
Solar Cell IV Curve Tracer – [Link]
Dilshan Jayakody documented his USB port base NPN transistor curve tracer project:
Curve tracer is an electronic test instrument to analyze the characteristics of transistors and other discrete semiconductors. In this post we construct USB base curve tracer to analyze properties of NPN transistors. This curve tracer is build around Microchip’s PIC18F4550 MCU and it use simple Windows based GUI application to plot captured data of a transistor.
USB curve tracer for NPN transistors – [Link]
James Lewis @ baldengineer.com discuss about switching regulator types and uses.
A switching voltage regulator is one of my favorite circuits. In school, they were the first circuits I built where I understood how transistors worked. In fact, they were the first circuit I saw an inductor being useful! Switching regulators are incredibly efficient when designed properly. Of course, this detail about design is important.
Basic Switching Voltage Regulator Tutorial – [Link]
This is a body thermometer using a thermistor sensor, Arduino and LCD display.
I’ve decided to provide a funny Arduino concept thermometer in case its the middle of the night, pharmacies are not working, you are not feeling well and you want to check your body temperature. If you have Arduino by your side, this is a life saver!
Arduino Body Thermometer + LCD I2C – [Link]
Moshe Gerstanhaber @ edn.com provides an simple ADC interface using instrumentation amplifier IC.
Real-world measurement requires the extraction of weak signals from noisy sources. High common-mode voltages are often present even in differential measurements. The usual approach to this problem is to use an op amp or an instrumentation amplifier and then perform some type of lowpass-filtering to reduce the background noise level.
Simple circuit provides precision ADC interface – [Link]
Johan wanted to shrink his Arduino based ISM radio node to fit in an AA battery compartment so AAduino was born.
The AAduino is an wireless Arduino clone the size of an AA battery with Keystone battery terminals rotated 180° to act as positive and negative terminals. It is powered by an ATMega328p and is fitted with an RFM69C companion. There is room for two DS18B20 temperature sensors and an indicator LED.
AAduino – Arduino Wireless in AA form factor – [Link]
Raj Bhatt shared another project with us. This time is a programmable digital timer with relay switch based on PIC16F628A.
Programmable relays find use in numerous automation applications such as automatic street light control, watering and pump control, HVAC, home automation, power plants automation in industries, etc. This article describes how to build a fully functional, one-channel programmable relay switch using the PIC16F628A microcontroller. It allows you to set both ON and OFF time. The maximum time interval that you can set for on and off operations is 99 hours and 59 minutes. Another interesting feature of this project is it offers cyclic option, which means you can choose to run it in a continuous loop of ON and OFF cycles. The device can be programmed through 4 push switches. The programming menu and device status are displayed on a 16×2 character LCD. The timing resolution of this relay timer is 1 minute. The timer also saves the user inputs to its internal EEPROM so that it can retain these values after any power supply interrupt.
PIC16F628A Programmable Digital Timer – [Link]
Programmable relays find use in numerous automation applications such as automatic street light control, watering and pump control, HVAC, home automation, power plants automation in industries, etc. This article describes how to build a fully functional, one-channel programmable relay switch using the PIC16F628A microcontroller. It allows you to set both ON and OFF time. The maximum time interval that you can set for on and off operations is 99 hours and 59 minutes. Another interesting feature of this project is it offers cyclic option, which means you can choose to run it in a continuous loop of ON and OFF cycles. The device can be programmed through 4 push switches. The programming menu and device status are displayed on a 16×2 character LCD. The timing resolution of this relay timer is 1 minute. The timer also saves the user inputs to its internal EEPROM so that it can retain these values after any power supply interrupt. Here are the summary of the features that this timer device has:
The hardware part of this project is very simple. The entire circuit runs off a regulated 5V power supply derived using the popular LM7805 linear regulator chip (Figure 1). To minimize the heat dissipation in the voltage regulator, the recommended input DC voltage to LM7805 is 9V, which can be easily obtained from a DC wall adapter. Diode D1 (1N4001) is used for reverse polarity protection in the circuit. S1 is a slide switch for turning the power supply on and off.
Figure 2 depicts the input and output setup. There are five tact switches in this project: one for microcontroller reset, and four for user inputs. The four input switches are named as Menu/+, Select, Enter, and Start/Stop. Their functions will be described in the software section. The status of the 4 input switches is read by the PIC16F628A microcontroller through ports RA2, RA3, RA4, and RB0. The output LCD is a standard HD44780-based display and is driven in 4-bit mode. The pin assignments for the LCD data and control signals are shown in Figure 2. S2 is another slide switch that allows manual control of the LCD backlight.
The output relay switch is driven through a NPN transistor (2N2222). The project also includes a DC buzzer that beeps when the relay switch changes its status. The relay and buzzer circuits are shown in Figure 3.
The PIC16F628A microcontroller runs at 4.0 MHz using an external resonator. The I/O pins of PIC16F628A, the resonator connection, and the in-circuit serial programmer (ICSP) header are shown in Figure 4.
Figure 1. Regulated +5V power supply unit
Figure 2. I/O circuit with PIC16F628A pin assignments
Figure 3. Relay and buzzer control circuit
Figure 4. PIC16F628A resonator and ICSP header connections
The PIC16F628A pin assignments for the LCD, switches, relay and buzzer circuits are listed in the following table.
The following figure shows the complete relay timer circuit soldered on a general-purpose prototyping board.
The programmable relay timer gets inputs from the 4 push buttons. Their functions are described as follows:
Menu/+ : This button allows you to navigate between various menu options such as ON time setup, OFF time setup, and Cyclic option setup. These options are displayed on the LCD. This button also serves as digit increment during time setup. The time is set in HH:MM format, which gives the minimum value of timing interval to be 1 min.
Select : This allows you to choose a displayed menu option as well as individual hour and minute digits. The selected digit is incremented by 1 when Menu/+ button is pressed.
Enter: When the appropriate hour and minutes are set, pressing the Enter button finalizes the time. The Cyclic option is also entered using this button.
Start/Stop: This push button is to start and stop the timer. If the timer is already on, you can stop it at anytime during its operation by pressing this button.
Now let’s see how it works. Suppose, the relay switch is needed to be turned on after 15 minutes for 10 minutes. This means the OFF time is 15 minutes and ON time is 10 minutes. Once the timer is started after entering the above times, the device will be turned on after 15 minutes and remained on for 20 minutes. After that it will be turned off again. If the Cyclic option is selected to 1, the timer will run in a loop and after another 15 minutes of OFF time, the relay will be turned on for next 10 minutes, and so on.
The firmware for this project is developed using mikroC Pro for PIC compiler from mikroElektronika. The time keeping is achieved using the Timer 0 module built inside the PIC16F628A. The Timer0 interrupt is enabled and run with 1:256 prescaler value to create a precise 500 ms (half-second) duration. The colon symbol between HH and MM digits blinks at 1 Hz. The half-second delay is looped 120 times to construct a minute-duration. You can download the complete project files including the source code and compiled HEX file in the attached file.
The following video shows the timer device in action.
Keynotes:
Author: Raj Bhatt (electronics enthusiast, and hardware maker, and founder of Embedded Lab; visit my Tindie store)
Here is a nice build of a LUX meter using BH1750 sensor and a Nokia 5110 LCD. The meter is controlled by an Arduino Pro Mini and is powered by a Li-Ion battery. The LCD backlight is controlled according to environment light and there is graphing capability of the measured light intensity.
That’s when I realized that I had an unused BH1750 light meter module laying around, which I bought some time ago but never used it. So I grabbed an Arduino, a Nokia 5110 LCD, wired everything up on a breadboard and had a functioning lux meter within a few hours. To make it a bit more fancy, I added some graphing functionality and made the LCD backlight switch on/off depending on the light level.
Mini Arduino Lux Meter – [Link]
Here is a basic tutorial on how to control ESP8266 over the internet using two buttons on a browser window. The article goes through Arduino IDE configuration and example code is included.
There are but a few things better than (succesfully) programming and using your Arduino. Surely one of those things is using your ESP8266 as an Arduino with WiFi!
Control ESP8266 over the internet – [Link]
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