Teardown, Repair & Analysis of an Agilent E4443A 3Hz – 6.7GHz PSA Series Spectrum Analyzer

In this episode Shahriar repairs an Agilent PSA Series Spectrum Analyzer. The instrument generates many errors during self-alignment and produces no measurements below 3.2GHz. The block diagram of the unit is thoroughly presented and various possible failure points are considered. Based on the observation of the noise floor, the most likely cause is the second LO module. The measurement of the LO power indicates that the second LO power is fall below nominal.

Teardown, Repair & Analysis of an Agilent E4443A 3Hz – 6.7GHz PSA Series Spectrum Analyzer – [Link]

Decoding and Encoding JSON with Arduino or ESP8266

In this blog post you’re going to learn how to decode (parse a JSON string) and encode (generate a JSON string) with the ArduinoJson library using the Arduino with the Ethernet shield. This guide also works with the ESP8266 and ESP32 Wi-Fi modules with small changes.

Decoding and Encoding JSON with Arduino or ESP8266 – [Link]

App note: Implementation of a single-phase electronic watt-hour meter using the MSP430AFE2xx

Another energy meter from Texas Instruments using MSP430AFE2xx. (PDF)

This application report describes the implementation of a single-phase electronic electricity meter using the Texas Instruments MSP430AFE2xx metering processors. It includes the necessary information with regard to metrology software and hardware procedures for this single chip implementation.

App note: Implementation of a single-phase electronic watt-hour meter using the MSP430AFE2xx – [Link]

WINXI – Arduino ZERO M0 Stick

WINXI – arduino ZERO Pro M0 compatible stick, RGB led, Micro SD, AtSamD21E18. Arduino zero pro compatible board with USB programming suitable for experienced users.

WINXI – Arduino ZERO M0 Stick – [Link]

LT8650S – Dual Channel 4A, 42V, Synchronous Step-Down Silent Switcher

The LT8650S is a dual step-down regulator that delivers up to 4A of continuous current from both channels and supports loads up to 6A from each channel. The LT8650S features the second generation Silent Switcher architecture to minimize EMI emissions while delivering high efficiency at high switching frequencies. This includes integration of bypass capacitors to optimize high frequency current loops and make it easy to achieve advertised EMI performance by eliminating layout sensitivity. Spread spectrum operation can further reduce EMI emissions. The fast, clean, low-overshoot switching edges enable high efficiency operation even at high switching frequencies, leading to a small overall solution size. Burst Mode operation features a 6.2μA quiescent current resulting in high efficiency at low output currents.

LT8650S – Dual Channel 4A, 42V, Synchronous Step-Down Silent Switcher – [Link]

SMA Solar readout

Jean-Claude wanted to read SMA solar inverter data over Bluetooth and so he build this project.

This is the first post of a 3-part series about reading out an SMA solar inverter over Bluetooth and displaying some readings every few seconds. Long-time readers may remember the Solar at last weblog post from several years ago and the SMA Relay, based on a JeeNode v6. The Bluetooth readout code was derived from Stuart Pittaway’s Nanode SMA PV Monitor code.

SMA Solar readout – [Link]

Raspberry Pi Backup Guide

Make a sustainable Raspberry Pi backup server and save your files from occasional loss.

Raspberry Pi backup is what you really need if you work on Raspbian. Believe me, you do! If you backup your Raspberry Pi SD card in due course, someday it may save your files and your project. Alike any other hardware, the RPi devices may sometimes simply stop working.

It can occur due to a number of reasons: overheating, errors, energy supply issues, cable connection failure… All these problems will make you unplug and plug-in again the device to restart it. And such actions taken repeatedly will certainly lead to spoiling your SD card you are saving your work files to.

On the other hand, you can damage or delete your files occasionally with your own hands! There a lot of examples when we do something wrong because of the overall tiredness, inattentiveness or just being in a hurry.

Control a 12V Lamp via SMS with Arduino

In this tutorial we’re going to show you how you can turn a 12V lamp on and off by sending SMS to your Arduino with the text “ON” and “OFF”, respectively. You can also request the current lamp state by sending an SMS with the text “STATE”, the Arduino should reply back with the text “Lamp is on” or “Lamp is off”

Control a 12V Lamp via SMS with Arduino – [Link]

Get Sensor Data From Arduino To Smartphone Via Bluetooth

Hariharan Mathavan at allaboutcircuits.com designed a project on using Bluetooth to communicate with an Arduino. Bluetooth is one of the most popular wireless communication technologies because of its low power consumption, low cost and a light stack but provides a good range. In this project, data from a DHT-11 sensor is collected by an Arduino and then transmitted to a smartphone via Bluetooth.

Required Parts

  • An Arduino. Any model can be used, but all code and schematics in this article will be for the Uno.
  • An Android Smartphone that has Bluetooth.
  • HC-05 Bluetooth Module
  • Android Studio (To develop the required Android app)
  • USB cable for programming and powering the Arduino
  • DHT-11 temperature and humidity sensor

Connecting The Bluetooth Module

To use the HC-05 Bluetooth module, simply connect the VCC to the 5V output on the Arduino, GND to Ground, RX to TX pin of the Arduino, and TX to RX pin of the Arduino. If the module is being used for the first time, you’ll want to change the name, passcode etc. To do this the module should be set to command mode. Connect the Key pin to any pin on the Arduino and set it to high to allow the module to be programmed.

Circuit to connect HC-05 with Arduino
Circuit to connect HC-05 with Arduino

To program the module, a set of commands known as AT commands are used. Here are some of them:

AT Check connection status.
AT+NAME =”ModuleName” Set a name for the device
AT+ADDR Check MAC Address
AT+UART Check Baudrate
AT+UART=”9600″ Sets Baudrate to 9600
AT+PSWD Check Default Passcode
AT+PSWD=”1234″ Sets Passcode to 1234

The Arduino code to send data using Bluetooth module:

//If youre not using a BTBee connect set the pin connected to the KEY pin high
#include <SoftwareSerial.h>
SoftwareSerial BTSerial(4,5); 
void setup() {
 String setName = String("AT+NAME=MyBTBee\r\n"); //Setting name as 'MyBTBee'
 BTSerial.print("AT\r\n"); //Check Status
 while (BTSerial.available()) {
 BTSerial.print(setName); //Send Command to change the name
 while (BTSerial.available()) {
void loop() {}

Connecting The DHT-11 Sensor

To use the DHT-11, the DHT library by Adafruit is used. Go here to download the library. When the letter “t” is received, the temperature, humidity, and heat index will be transmitted back via Bluetooth.

circuit to connect DHT-11 with Arduino
circuit to connect DHT-11 with Arduino

The code used to read data from the DHT sensor, process it and send it via Bluetooth:

#include "DHT.h"
#define DHTPIN 2 
#define DHTTYPE DHT11 
void setup() {

void loop()
{ char c; 
 c = Serial.read(); 
void readSensor() {
 float h = dht.readHumidity();
 float t = dht.readTemperature();
 if (isnan(h) || isnan(t)) {
 Serial.println("Failed to read from DHT sensor!");
 float hic = dht.computeHeatIndex(t, h, false);
 Serial.print("Humidity: ");
 Serial.print(" %\t");
 Serial.print("Temperature: ");
 Serial.print(" *C ");
 Serial.print("Heat index: ");
 Serial.print(" *C ");

Developing The Android App

The flow diagram of the Android app is illustrated below,

Flow diagram of the Android app
Flow diagram of the Android app

As this app will be using the onboard Bluetooth adapter, it will have to be mentioned in the Manifest.

uses-permission android:name="android.permission.BLUETOOTH"

Use the following code to test if Bluetooth adapter is present or not,

BluetoothAdapter bluetoothAdapter=BluetoothAdapter.getDefaultAdapter();
if (bluetoothAdapter == null) {
Toast.makeText(getApplicationContext(),"Device doesnt Support Bluetooth",Toast.LENGTH_SHORT).show();

The following part of the code deals with reading the data,

int byteCount = inputStream.available();
 if(byteCount > 0)
 byte[] rawBytes = new byte[byteCount];
 final String string=new String(rawBytes,"UTF-8");
 handler.post(new Runnable() {
 public void run()

To send data, pass the String to the OutputStream.


The complete source code of the Android application can be downloaded from here.


Power up the Arduino and turn on the Bluetooth from your mobile. Pair with the HC-05 module by providing the correct passcode – 0000 is the default one. Now, when “t” is sent to the Arduino, it replies with the Temperature, Humidity, and Heat Index.

the application screen
the application screen