https://jpralves.net/2015-12-29T00:00:00+00:00Joao Alves personal site with information related to electronics, science, technology and computers2015-12-29T00:00:00+00:002015-12-29T00:00:00+00:00João Alvestag:jpralves.net,2015-12-29:post/2015/12/29/real-time-clock.html

<p><img alt="" src="https://jpralves.net/imgt/2015/12/Ci35_1_DS1307RTC_t.jpg" /></p><p>Being near the end of the year, we decided to build a circuit to control a Real Time Clock (RTC). An RTC is characterized by being an autonomous time source that works independently from the rest of the circuit. To …</p>

2015-12-22T00:00:00+00:002015-12-22T00:00:00+00:00João Alvestag:jpralves.net,2015-12-22:post/2015/12/22/christmas-tree-with-leds-circuit.html

<p><img alt="" src="https://jpralves.net/imgt/2015/12/Ci34_1_ChristmasLEDs1_t.jpg" /></p><p>Being in the Christmas season we will be building a circuit that fits the Christmas spirit - a Christmas tree with LEDs. This circuit is very simple and allows you to make the LEDs blink alternately in three groups. The circuit …</p>

2015-12-15T00:00:00+00:002015-12-15T00:00:00+00:00João Alvestag:jpralves.net,2015-12-15:post/2015/12/15/servo-tester.html

<p><img alt="" src="https://jpralves.net/imgt/2015/12/Ci33_1_TesteServos_t.jpg" /></p><p>In this article we will build a circuit to control the position of a servo. Servos are typically small in size and are typically used to operate remotely controlled robots, cars or airplanes via radio. They are also used in …</p>

2015-12-08T00:00:00+00:002015-12-08T00:00:00+00:00João Alvestag:jpralves.net,2015-12-08:post/2015/12/08/clap-switch.html

<p><img alt="" src="https://jpralves.net/imgt/2015/12/Ci32_1_ClapSwitch_t.jpg" /></p><p>Today we will build a circuit activated by clapping sounds. This allows you to open or close a circuit by clapping your hands. This circuit is made using a sound sensor, which detects the loud sound (of clapping) as input …</p>

2015-12-01T00:00:00+00:002015-12-01T00:00:00+00:00João Alvestag:jpralves.net,2015-12-01:post/2015/12/01/unipolar-motor-controller.html

<p><img alt="" src="https://jpralves.net/imgt/2015/12/Ci31_1_ControladorMotorUnipolar_t.jpg" /></p><p>Two circuits will be built today to control Unipolar motors. A unipolar motor is a type of step motor described as needing only a current source. By contrast, bipolar motors require two current sources to move. The complexity of this …</p>

2015-11-24T00:00:00+00:002015-11-24T00:00:00+00:00João Alvestag:jpralves.net,2015-11-24:post/2015/11/24/dc-motor-controller.html

<p><img alt="" src="https://jpralves.net/imgt/2015/11/Ci30_1_ControladorMotorDC_t.jpg" /></p><p>Today we will build a circuit to control DC motors. Electric motors of all kinds work thanks to electromagnetism. They convert electric energy into mechanical energy. DC motors are relatively simple control motors. They are motors that have two modes …</p>

2015-11-17T00:00:00+00:002015-11-17T00:00:00+00:00João Alvestag:jpralves.net,2015-11-17:post/2015/11/17/timer-with-555.html

<p><img alt="" src="https://jpralves.net/imgt/2015/11/Ci29_1_Temporizador555_t.jpg" /></p><p>Today we will build a circuit that is a timer. The IC 555 was used. This was set to Mono-stable mode. When the button is pressed the time starts and the LED lights up. After a while it goes off …</p>

2015-11-10T00:00:00+00:002015-11-10T00:00:00+00:00João Alvestag:jpralves.net,2015-11-10:post/2015/11/10/obstacle-detector-using-infrared.html

<p><img alt="" src="https://jpralves.net/imgt/2015/11/Ci28_1_DetectorIR_t.jpg" /></p><p>Today we will build a circuit that detects the interruption of an infrared beam allowing an alarm to be created. The LM358 IC has two comparators. Pin 3 which is the non-inverted end of the voltage comparator is connected to …</p>

2015-11-03T00:00:00+00:002015-11-03T00:00:00+00:00João Alvestag:jpralves.net,2015-11-03:post/2015/11/03/infrared-led-alarm.html

<p><img alt="" src="https://jpralves.net/imgt/2015/11/Ci27_1_AlarmeIR_t.jpg" /></p><p>Today we will build a circuit that detects the interruption of an infrared beam allowing an alarm to be created. The LM358 IC has two comparators. Pin 3 which is the non-inverted end of the voltage comparator is connected to …</p>

2015-10-27T00:00:00+00:002015-10-27T00:00:00+00:00João Alvestag:jpralves.net,2015-10-27:post/2015/10/27/shutdown-button-for-raspberry-pi.html

<p><img alt="" src="https://jpralves.net/imgt/2015/10/Ci26_1_BotaoRaspberryPI_t.jpg" /></p><p>Today we will build a small circuit that lets you execute commands in Raspberry Pi to do whatever we want when a button is pressed (in our case to start the shutdown process). This circuit is quite simple and requires …</p>

2015-10-20T00:00:00+01:002015-10-20T00:00:00+01:00João Alvestag:jpralves.net,2015-10-20:post/2015/10/20/adc-for-raspberry-pi.html

<p><img alt="" src="https://jpralves.net/imgt/2015/10/Ci25_1_ADCRaspberryPI_t.jpg" /></p><p>Using an MCP3008 IC we will add the ability to read analog values on a Raspberry Pi. The Raspberry Pi unlike the Arduinos natively has no way of reading analog data. By adding an integrated as the MCP3008 we can …</p>

2015-10-13T00:00:00+01:002015-10-13T00:00:00+01:00João Alvestag:jpralves.net,2015-10-13:post/2015/10/13/signal-meter-vu-meter.html

<p><img alt="" src="https://jpralves.net/imgt/2015/10/Ci24_1_MedidorSinal_t.jpg" /></p><p>Today a circuit will be built using an LM3915 IC and it will visually represent the intensity of an audio signal. The LM3915 has an amplitude of 30 dB and the 10 LEDs are activated in 3 dB intervals. If …</p>

2015-10-06T00:00:00+01:002015-10-06T00:00:00+01:00João Alvestag:jpralves.net,2015-10-06:post/2015/10/06/doorbell.html

<p><img alt="" src="https://jpralves.net/imgt/2015/10/Ci23_1_CampainhaPorta_t.jpg" /></p><p>Today a circuit will be built to make a two-tone doorbell. We will use two ICs, one CD4060 which is an oscillator with a 14-step binary counter and a CD4001 that implements 4 NOR ports. The first integrated will divide …</p>

2015-09-29T00:00:00+01:002015-09-29T00:00:00+01:00João Alvestag:jpralves.net,2015-09-29:post/2015/09/29/logic-probe.html

<p><img alt="" src="https://jpralves.net/imgt/2015/09/Ci22_1_SondaLogica_t.jpg" /></p><p>Today we will build two circuits that work as logic probes that inform us of the state of the signal under analysis through LEDs. One circuit uses the IC CD4001 and the other uses the IC CD4011, the first implements …</p>

2015-09-22T00:00:00+01:002015-09-22T00:00:00+01:00João Alvestag:jpralves.net,2015-09-22:post/2015/09/22/random-signal-generator.html

<p><img alt="" src="https://jpralves.net/imgt/2015/09/Ci21_1_GeradorDadosAleatorios_t.jpg" /></p><p>Today we will build two circuits that, with the help of two integrated chips and some components, allow us to generate random results. Both circuits use a CD4011 IC that implements 4 NAND ports with buffer and a CD4017 IC …</p>

2015-09-15T00:00:00+01:002015-09-15T00:00:00+01:00João Alvestag:jpralves.net,2015-09-15:post/2015/09/15/simple-fm-transmitter.html

<p><img alt="" src="https://jpralves.net/imgt/2015/09/Ci20_1_EmissorFMsimples_t.jpg" /></p><p>Today we will build a circuit to create a very simple FM transmitter. This circuit like others is well publicized on the Internet and presents a very simple configuration since it only uses an NPN Transistor. Note that this circuit …</p>

2015-09-08T00:00:00+01:002015-09-08T00:00:00+01:00João Alvestag:jpralves.net,2015-09-08:post/2015/09/08/multiple-inputs-parallel-to-series.html

<p><img alt="" src="https://jpralves.net/imgt/2015/09/Ci19_1_MultiplosInputs_t.jpg" /></p><p>Today we will build a circuit to read multiple inputs (buttons or others) using an IC that converts a parallel input into a _output series. The Circuit uses a 74HC165 IC to read the inputs. Pull-up resistors are used in …</p>

2015-09-01T00:00:00+01:002015-09-01T00:00:00+01:00João Alvestag:jpralves.net,2015-09-01:post/2015/09/01/piano-with-555.html

<p><img alt="" src="https://jpralves.net/imgt/2015/09/Ci18_1_Piano555_t.jpg" /></p><p>Today we will build a circuit that uses the IC 555 along with buttons and resistances to play the 9 musical notes. This circuit has a wave generator 555 configured as an astable multivibrator circuit. This type of operation is …</p>

2015-08-25T00:00:00+01:002015-08-25T00:00:00+01:00João Alvestag:jpralves.net,2015-08-25:post/2015/08/25/led-detects-light.html

<p><img alt="" src="https://jpralves.net/imgt/2015/08/Ci17_1_LEDdetetaLuz_t.jpg" /></p><p>Today we will build a circuit that uses an LED in a curious way - to detect brightness. We all know that LEDs have a certain color but some of these LEDs can also detect light. Obviously they do not have …</p>

2015-08-18T00:00:00+01:002015-08-18T00:00:00+01:00João Alvestag:jpralves.net,2015-08-18:post/2015/08/18/ohmmeter-with-auto-ranging.html

<p><img alt="" src="https://jpralves.net/imgt/2015/08/Ci16_1_OhmMeterAutoRanging_t.jpg" /></p><p>Today we will build two circuits to calculate the value of a resistor. The principle used in these circuits is the voltage division. The measurement is made with an analog port of a micro-controller. Hoje iremos construir dois circuitos para …</p>

2015-08-11T00:00:00+01:002015-08-11T00:00:00+01:00João Alvestag:jpralves.net,2015-08-11:post/2015/08/11/comparator-night-light.html

<p><img alt="" src="https://jpralves.net/imgt/2015/08/Ci15_1_ComparatorNightLight_t.jpg" /></p><p>In the circuit of this article we will build a voltage comparator using an integrated chip called LM393. The LM393 is a dual difference comparator. This means that you have two independent voltage comparators. The circuit compares the input voltages …</p>

2015-08-04T00:00:00+01:002015-08-04T00:00:00+01:00João Alvestag:jpralves.net,2015-08-04:post/2015/08/04/infrared-detector.html

<p><img alt="" src="https://jpralves.net/imgt/2015/08/Ci14_1_InfraredDetector_t.jpg" /></p><p>In today’s circuit we will build an infrared detector. Additionally we will build a circuit to detect the type of frequency and to which manufacturer the codes belong. The latter uses an Arduino and a library to obtain this …</p>

2015-07-28T00:00:00+01:002015-07-28T00:00:00+01:00João Alvestag:jpralves.net,2015-07-28:post/2015/07/28/level-shifter.html

<p><img alt="" src="https://jpralves.net/imgt/2015/07/Ci13_1_t.jpg" /></p><p>Increasingly, when designing a circuit, we find components that operate at different voltages than the microcontroller. This requires that, to work with them, it is necessary to implement a level shifter, that is, to ensure that there is a transition …</p>

2015-07-21T00:00:00+01:002015-07-21T00:00:00+01:00João Alvestag:jpralves.net,2015-07-21:post/2015/07/21/hd44780-character-lcd-displays.html

<p><img alt="" src="https://jpralves.net/imgt/2015/07/Ci12_1_t.jpg" /></p><p>The circuits presented today allow the control of a LCD display that has a very common chip to be controlled by a micro-controller HD44780 or one that is compatible with this one. There are several formats for this LCD, however …</p>

2015-07-14T00:00:00+01:002015-07-14T00:00:00+01:00João Alvestag:jpralves.net,2015-07-14:post/2015/07/14/atari-punk-console.html

<p><img alt="" src="https://jpralves.net/imgt/2015/07/Ci11_1_t.jpg" /></p><p>The circuit presented is a very popular circuit based on two IC 555’s. It produces a set of audible sounds that can be changed using the two potentiometers. The original circuit was published by Forrest Mims in a book …</p>

2015-07-07T00:00:00+01:002015-07-07T00:00:00+01:00João Alvestag:jpralves.net,2015-07-07:post/2015/07/07/transistors-tester.html

<p><img alt="" src="https://jpralves.net/imgt/2015/07/Ci10_1_t.jpg" /></p><p>Today will be presented a circuit to test bipolar PNP and NPN transistors . It is a circuit based on the 555. This circuit lets you check the type of transistor we have and if it is working properly or not …</p>

2015-06-30T00:00:00+01:002015-06-30T00:00:00+01:00João Alvestag:jpralves.net,2015-06-30:post/2015/06/30/charlieplexing.html

<p><img alt="" src="https://jpralves.net/imgt/2015/06/Ci09_1_t.jpg" /></p><p>Today’s circuit aims to control quite a few LEDs with few pins and without using other integrated chips. The technique used is called charlieplexing and was proposed in 1994 by Charlie Allen of Maxim, having nevertheless been the subject …</p>

2015-06-23T00:00:00+01:002015-06-23T00:00:00+01:00João Alvestag:jpralves.net,2015-06-23:post/2015/06/23/buttons-and-more-buttons.html

<p><img alt="" src="https://jpralves.net/imgt/2015/06/Ci08_1_t.jpg" /></p><p>We will present several ways to use buttons as inputs for a circuit. The state of a button is the most basic form of binary logic it is open or closed, however when assembling a circuit you have to keep …</p>

2015-06-16T00:00:00+01:002015-06-16T00:00:00+01:00João Alvestag:jpralves.net,2015-06-16:post/2015/06/16/7-segment-and-8x8-matrix-led-controls.html

<p><img alt="" src="https://jpralves.net/imgt/2015/06/Ci07_1_t.jpg" /></p><p>Sending information from the micro-controller to the user is extremely important to help in the interaction between the two. The use of 7 Segment LEDs is a common practice since they are simple to use devices that allow the sending …</p>

2015-06-09T00:00:00+01:002015-06-09T00:00:00+01:00João Alvestag:jpralves.net,2015-06-09:post/2015/06/09/24-led-control.html

<p><img alt="" src="https://jpralves.net/imgt/2015/06/Ci06_1_t.jpg" /></p><p>The circuit presented today is a circuit built with 3 Shift Registers - 74HC595. This circuit allows controlling up to 24 outputs - in the case of LEDs and controlling them independently. A CSEduino was used to control the 24 outputs. Since …</p>

2015-05-26T00:00:00+01:002015-05-26T00:00:00+01:00João Alvestag:jpralves.net,2015-05-26:post/2015/05/26/adjustable-voltage-regulator.html

<p><img alt="" src="https://jpralves.net/imgt/2015/05/Ci04_1_t.jpg" /></p><p>These circuits were made using two common adjustable voltage regulators - the LM317T and the AMS1117ADJ. The LM317T is an adjustable voltage linear regulator that is very popular. It was invented in 1970 and is still used today. This is very …</p>

2015-05-19T00:00:00+01:002015-05-19T00:00:00+01:00João Alvestag:jpralves.net,2015-05-19:post/2015/05/19/5v-voltage-regulator.html

<p><img alt="" src="https://jpralves.net/imgt/2015/05/Ci03_1_t.jpg" /></p><p>These circuits were made using four very common voltage regulators - the LM7805, the LM2940, the LM1117 and the AMS1117. The LM7805 is a linear voltage regulator that is very popular, because to put it to work no more components are …</p>

2015-05-12T00:00:00+01:002015-05-12T00:00:00+01:00João Alvestag:jpralves.net,2015-05-12:post/2015/05/12/555-simple-sequencer.html

<p><img alt="" src="https://jpralves.net/imgt/2015/05/Ci02_1_t.jpg" /></p><p>This circuit serves as the basis for a huge set of circuits ranging from led chasers, Knight Rider, Electronic Roulette, Semaphores, etc. Let’s present here two of this kind of circuits. The 555 IC is well known for being …</p>

2015-05-05T00:00:00+01:002015-05-05T00:00:00+01:00João Alvestag:jpralves.net,2015-05-05:post/2015/05/05/2-transistor-led-flasher.html

<p><img alt="" src="https://jpralves.net/imgt/2015/05/Ci01_1_ProtoN1_t.jpg" /></p><p>Building of two circuits that flash alternately to two LEDs at a fixed cadence. These are very basic circuits and they show two ways of building circuits using transistors BJT PNP and NPN. These are classic circuits that use the …</p>