Basic Circuits
Raspberri Pi
Remote Control

Noob 7868

Undefined Job

Introduction to impedanceImpedance and resistance have the same unit, both are Ω. Resistance has an obstructive effect on current, and similarly, impedance has an obstructive effect on current.Impedance can be any combination of resistance, capacitance, and inductance that hinders the current. Since the impedance of the capacitor to the direct current is infinite, and the impedance of the inductance to the direct current is zero, the impedance is more used to describe the obstructive effect of the current in the AC circuit.High impedance refers to a large impedance value, and low impedance refers to a small impedance value.What is a hornThe trumpet is divided into several different musical instruments, a kind of wind instrument, with thin upper part and thick lower part, mostly made of copper. The other is a modern electro-acoustic component, whose function is to convert electrical signals into sound, which is also called a speaker. It can also be used to describe someone who advocates and promotes for others.A horn is actually a conversion device that converts electrical energy into sound. When different electronic energy is transmitted to the coil, the coil generates a kind of energy to interact with the magnetic field of the magnet. This interaction causes the paper plate to vibrate because the electronic energy changes at any time. The coil of the horn will move forward or backward, so the paper tray of the horn will move accordingly. This action changes the density of the air and produces sound.Speaker impedanceIn general audio equipment, the impedance of the speaker, the input impedance of the front and rear amplifiers, the output impedance of the front stage, (the latter is usually not called the output impedance, but the output internal resistance), the transmission of the signal line Impedance resistance (or characteristic impedance) and so on. Since the unit of impedance is still ohms, Ohm's law also applies, so in a nutshell, under the same voltage, the higher the impedance, the less current will flow, and the lower the impedance, the more current will flow. The most common horn impedance marked value is eight ohms, which means that when the pair of speakers is tested in the factory, when a 1KHz sine wave signal is input, its impedance value is eight ohms; or it is in the working frequency response of the speaker Within the range, an average impedance value.It is not a fixed value, but varies with frequency. When the rear stage outputs a fixed voltage to the speaker, according to Ohm’s law, a four-ohm speaker will flow twice as much current as an eight-ohm speaker. When the four-ohm speaker is connected, it will automatically become 200 watts. When the impedance value of the speaker drops all the way, the subsequent stage outputs a fixed voltage, and the current flowing through it will become larger and larger. In the end, it is a bit like a direct short-circuit of the speaker wire, so the impedance value is sometimes as low as one ohm. Limit, beyond this range, the machine will burn. This is what most people often say: The power of the subsequent stage does not need to be large, but the output current seems to be large.The difference between the speaker 4 ohm and 8 ohm is1. The internal resistance of a 4 ohm speaker is 4Ω; the internal resistance of an 8 ohm speaker is 8Ω.2, 4 ohm speakers, because of the small internal resistance, the voltage change will be more obvious than 8 ohms, so the sensitivity of the sound quality is higher than that of 8 ohms.3, 8 ohm speakers, the power is relatively small, suitable for playing bass, appear more subdued, suitable for high-quality audio.

  about 12 days ago

In this video, my 3D printed 5mm LED Diffusers designs are demonstrated with 5mm RGB LED flasher. the STL files can be reached through thingverse link below:


Video link:


  about 24 days ago

Arnaldo Garcia

Undefined Job

Hola a todos, les comparto un proyecto que estuve pensando y lo lleve a la simulación en proteus, no he logrado probarlo realmente o si funcione como tal cual sucede en la simulación, el proyecto consta de un LM358 como comparador de voltaje, un voltaje de referencia a 4.1v por el No inversor, la lectura es tomada de la tensión que proporciona la batería y al alcanzar los 4.15v deja de cargar la batería, mi duda es si se pueda usar el 4066 el cual hará el corte de la carga.

  about 1 month ago


Electronic Engineer and YouTuber

Hi guys. This here is my design of a coilgun which is a project I was preparing to make for a long time and I finally made a first version. Before we start, I have to warn you that this is a quite dangerous project for 2 reasons. First, well it fires projectiles at high speed. And second, it works with very high voltage, around 500V so please be careful if you want to make the same project. Use proper tools, stay insulated and never touch the exposed wires while the board is powered on. Also make sure that you fully discharge the huge capacitors each time, because these could store a huge amount of charge. Ok so my design is a bit special and you will see that it is made out of separated PCB for each stage. So if you want more power and more speed, you can just add another stage. Each segment PCB works by its own, having the coil, the capacitor, the power control and the bullet detector so it is very easy to add more stages. So, what do you think? Would this be able to fire through a cardboard box? That sound quite easy, right?. But what about a 4mm plywood sheet? What about some plexiglass? What about some 3mm MDF which is a strong material? Well, stick till the end of the tutorial to find out and by the way, below you can find all that you need to make this same project, such as my schematics, my PCB designs, the part list and so on. So, safety glasses on, and let’s get started.

  about 1 month ago

Noob 7868

Undefined Job

This metal detector, due to the use of a quartz crystal oscillator and a difference frequency signal multiplier, makes the circuit stable and extremely sensitive. Although the circuit uses five ICs, the cost is very low (30 yuan About), its use effect is no less than a few thousand yuan of imported products. This machine can be widely used in the detection of some small metal objects such as archaeology, military, etc. or metal objects with long distance and large buried depth.


Circuit design principle: see the diagram below the principle. By IC1, CD4011B and Ll and related components constitute an induction oscillator, RP1 is the frequency trimming potentiometer. The three NAND gates of IC1 form an inductive oscillator circuit, and the three NAND gates of IC2 and a crystal form the local oscillator. The local oscillator signal and the inductive signal are at a frequency difference in a NAND gate of IC1, from IC1's ⑧ The pin outputs a difference frequency signal. Due to the low beat frequency, especially the small changes in the frequency induced by tiny metal objects, if you directly listen to the beat frequency signal, it is difficult to reflect it in your ears. Therefore, the difference frequency signal can be multiplied to meet the requirements of the ear to distinguish frequency changes. Since the IC3 CD4046B phase-locked loop circuit and the IC4 CD4017B decimal distribution circuit constitute a multi-stage adjustable frequency multiplication circuit, the adjustment range is 1-9 times and a total of 9 gears, which can be selected according to the actual situation. The difference frequency signal is input from pin 14 of CD4046, and the frequency multiplier signal is output from pin ④, and then sent to IC5 (LM386) through the volume potentiometer RP2, which is amplified and output to the speaker or earphone to emit sound.


Production points: L1 uses 0.45mm enameled wire, wound into a coil with a diameter of 60cm, the number of turns is 30, and the inductance is about 1.2mH. JT can choose 400-500kHz crystal for color TV, VD is MV2105, C1~C6 can choose mica or black dot ceramic capacitor to meet the requirements. First, adjust Cl and RP1 so that the output frequency of IC1⑩ pin is the same as that of IC2⑩ pin. At this time, IC1(11) should have no frequency output, and there should be no audio in the earphone. The frequency multiplier gear can be selected with a 1x9 switch. Frequency multiplier selection, generally the smaller the metal object, the greater the depth, the higher the multiplier, on the contrary, the larger the metal object, the closer the multiplier should be lower.


In order to avoid external interference, you should choose headphones for better results. The circuit can be installed in a plastic box, and the earphone socket is installed on the handle. The overall appearance is shown in the figure below.


  about 2 months ago

Noob 7868

Undefined Job

Home-made humidifier diagram

Production steps:

Step 1: Required materials:

Empty baby wipes box

Aluminum foil (approximately 7.5 by 5 inches, 19 by 12.7 cm)

20 ounces (about 560 ml) bottled water bottle

80mm computer cooling fan, including mounting screws

Single pole double throw switch (actually any switch is fine)

9V AC/DC power converter

Power adapter

Humidification filter

A short piece of wire (about 6 inches, a little more than 15 cm long)



Step 2: Tools needed:

Electric grinder with glass fiber reinforced cutting wheel

Wireless handheld drill

1/4 inch drill bit

5/32 inch drill bit

Files for Jewelry

Iron scissors

Hot melt glue gun

Electric screwdriver

Electric soldering iron



Step 3: Assembly steps: spread out the container, trim the upper cover, and install the bottle.


Step 4: Connect the electronic parts, the final product


Step 5: We will use a used baby wet tissue box as a container. The upper part of the box is rounded, making it difficult to put things on it. Rather than completely removing the upper structure, we might as well modify it so that it can fix other things and facilitate the handling of the internal space, including cleaning and filter replacement.


Step 6: Use the cutting wheel of the electric grinder to make a 6.25 by 4.5 inch (about 15.9 cm by 11. cm) space on the top of the box, leave about 1/4 inch (6.35 mm) on the side not to cut, so that Can reserve the clamshell roller space of the box cover.


Step 7: Next, we need to drill two 1/4 inch small holes in the front of the box cover, which are in the area where the switch button of the box cover is located. After modification, it will be used to install the upper plate structure and be able to fix it.


Step 8:

On the left side of the box, we need to make a ventilation structure to extract air through a filter element that absorbs water vapor. This design is aimed at installing the bottle on the left side of the box.

First you need to measure up to about 1.5 inches (3.8 cm) from the bottom, and then you start to drill a 1/4 inch hole in the side. The more holes, the better the airflow after passing through the filter element. I made 4X7 holes.

Don't forget to use a file or sandpaper to clean the edges of cutting and drilling.


Step 9:

Now we expand the top and decide where to proceed next.


Step 10:

When looking at the box from the front, we hope that the bottle and the vent are on the same side, and the water supply bottle for the humidifier should be beside the exhaust fan. So we made two holes of 2.75 inches (approximately 7 cm) in diameter on the cover 0.75 inches (1.9 cm) from the edge, with a distance of 0.5 inches (1.27 cm) between the two holes.


Step 11:

We will also install a power switch. Please note that all marking and cutting will be done on the reverse side of the cover, so that the electric grinder will not damage the appearance during operation. Pay attention to which side is used for bottling. This side needs to be more careful when cutting to ensure that the bottles are well connected.


Step 12:

We use the cutting wheel of an electric grinder to make a hole, which can not go out of bounds when cutting, and finally use a file to correct the cut. Of course, the polishing wheel of the electric grinder can also be used to trim the incision. It is best to use a file to process the mouth of the bottle, because the bottle fits well.


Step 13:

It may be necessary to file off the mark and then install the bottle for testing to see if you need to file off a little more material. When cutting the switch hole, we use a 1/4 inch drill to make a hole in the middle, and then use a file to complete the entire area. The bottling mouth should be processed to be smoother to avoid damage to the bottle.


Step 14:

You can widen the hole, and then add a ring of gasket on the side to better protect the bottle and have a better appearance and packaging. Well, maybe there is not enough space for this step of processing.


Step 15:

Then we want to measure the hole where the fan is installed. The easiest way is to lift the fan weight in the hole and mark two installation eyes on the diagonal. We are going to use a 5/32 inch drill bit to drill the mounting hole. Now work with iron scissors to smooth the corners of the cover so that it can cover the box. Connect the bottom surface of the lid with the groove we made in the front of the box. Check the excuse. You may need to remove a lot of material to cover the lid without deformation, or even increase the depth of the groove.


Step 16:

To complete this step, we have to use the help of hot melt glue to fill in all the gaps on the lid. This not only ensures that the lid will not be misaligned, but also prevents air leakage. Do not seal the big opening on the front, it is used to install the power cord, and it will eventually become the back of the finished product.

Now play as you like and paint it. Make sure to seal all holes with tape from the inside so that the spray paint does not get inside.


Step 17:

This step is very intuitive. After inserting the bottle in the box, the water level of the bottle will bottom out. We need to modify it slightly so that the water level of the box after it is discharged is only 1/4 inch high. This is our purpose, so that the filter paper absorbs moisture and diffuses the moisture into the air. First of all, when the bottle has not been opened, we remove the cap, then use the electric grinder cutting wheel to cut out 4 1/4 inch wide and 1/2 inch deep notches at the mouth of the bottle, and then remove them with a file. Cut out and you are ready to install.


Step 18: Connect electronic parts

Now we are going to wire up and install electronic parts. Install the switch on the switch hole, and install the fan on the back of its opening (that is, in the cover). Fix it on the bottom edge of the switch and the plate with a few lumps of hot melt glue. We need to extend the power interface from the power hole to facilitate welding.


Step 19:

We only need basic soldering skills to assemble.


Step 20:

Weld the negative pole of the fan and the power switch together, then weld the positive wire of the fan to the switch, and weld the remaining wire to the other end of the switch. Now put the power socket in its place and fill the hole with hot melt glue. Connecting parts exposed to the outside world can be handled well with this method.


Step 21:

We can easily add LEDs to the circuit to display power. The noise produced by the fan is acceptable. Just choose a suitable resistor to add to the LED, because this device uses a power supply of 9 volts or more.


Step 22:

All that remains to be done is to cut the humidification filter paper into a suitable size, set it in place, and use any scissors at home to complete it. There is no need to use any shelf to fix the filter paper, the water bottle itself can be fixed.


Step 23:

Cut the filter paper to 3.5 by 4 inches (8.89 by 10.16 cm), place it against the vent of the box, and seal the lid to add water. Fill the water bottle and quickly buckle it upside down into the box. The bottom 1/4 inch of the box will be filled with water. Plug in the 9V AC/DC converter on the back, flip the switch, and enjoy replenishing air moisture.


Step 24: How it works

The moisture at the bottom of the container is sucked by the filter paper, and the fan draws air through the vents, and the moisture is taken away by the filter paper. Then the ideal humidity air is blown out by the top fan. When the water volatilizes into the air, the water bottle will add water to the container from time to time.


Step 25:

A full 20oz (560ml) water bottle can last for 8 to 9 hours, depending on the quality of the fan you use, enough to make it work smoothly in the office. Remember to replace the filter element every month, or when the upper part of it turns brown. Turning on the fan when there is no water can speed up the drying of the filter element and help prevent the growth of mold.

  about 2 months ago

Noob 7903

Undefined Job

Hello,I've mount a levitation module I bought on Banggood. When I present a magnet on the top, I've only a lighting LED and nothing more. The potentiometers don't seems to act anything.Someone can help me?There's two jumpers and I saw in another version of module that's can be used for plug an amperemeter to measure something, but what value?[URL= 1.html][IMG] 1[/IMG][/URL][URL= 1.html][IMG] 1[/IMG][/URL][URL= 1.html][IMG] 1[/IMG][/URL]

  about 2 months ago

Noob 7868

Undefined Job

The STM32F103C8T6 board-also known as Blue Pill-is the development board M3 microcontroller of ARM Cortex. It looks very similar to Arduino Nano, but it contains more functions.In this article, I will show you how to set up STM32 using Arduino IDE and show you how to program directly from the USB UART module.STM32 overview "Blue Pill"If you look at this $2 microcontroller, the first thing you see is its jumper pins, which are used to use the default USART bootloader. There is also a micro USB port on the board, but unfortunately it cannot be used for programming because it does not have an associated bootloader.Compared with the official Arduino boards, these boards are very cheap and the hardware is open source. In addition to the microcontroller, the board can also accommodate two crystal oscillators-an 8MHz crystal and a 32KHz crystal-which can be used to drive the internal RTC (Real Time Clock). Therefore, the MCU can work in deep sleep mode, which is very suitable for battery-powered applications.To program the board, we need to use a simple USB to UART converter, and then we can program it directly from the computer via USB.PIC01STM32 pinoutRequired materialsSTM32 F103C8T6USB to UART converter (FTDI)JumperBreadboardArduino IDEWiring projectConnect the circuit boards according to the connections shown in the Fritzing diagram below and connect them to the computer.PIC02Fritzing diagramUse the build settings with jumpers in place.Connect the jumper as shown in the figure below, set the circuit board to DFU mode (device firmware upgrade), and then press the "reset" button.PIC03 04Set up STM32 on Arduino IDEOpen the Arduino IDE and select preferences.PIC05Click the "Other Board URL" option and add this URL after the comma: 07Then click Tools→Boards→Board Manager.PIC08After performing the above steps, you can see STM32 in the board list. Now select STM32F103C.PIC09Because we use the UART module to upload code, we choose Upload Method as Serial.PIC10Select Blink sketch from the example.PIC11Use "PC13" to change the LED pin number, as shown in the screenshot below. This is the name of the built-in LED in the circuit boardPIC12Project source codevoid setup() {// change pin PC13pinMode(PC13, OUTPUT);}//infinite loopvoid loop() {digitalWrite(PC13, HIGH); // turn the LED on (HIGH is the voltage level)delay(1000); // wait for a seconddigitalWrite(PC13, LOW); // turn the LED off by making the voltage LOWdelay(1000); // wait for a second}Upload the code to the Arduino IDEUpload the code now.PIC13Uploaded successfully!in conclusionIf the program has been uploaded successfully, you should see the green LED flashing at 1 second intervals. You can also use this program to increase or decrease the delay of the LED lights.After uploading the program, you should change the jumper back to the normal mode so that the uploaded program will automatically start to execute when the circuit board is turned on next time.

  about 2 months ago

Noob 7868

Undefined Job

  about 2 months ago


Electronic Engineer and YouTuber

This PCB is a metal detector. The circuit is very easy and I will do my best in this tutorial to explain to you how it works. I use real examples and animations in the video below so you will understand everything. The PCB is interesting because it already has the coils on the board made with the copper tracks, so we don’t need external coils made with copper wires. I will share with you the schematic for this project and the GERBER files in case you want to order this same PCB and start making tests with it. All the links are below. So guys, what do you think? Will this PCB be capable of detecting metal and if yes, how good is it? So, let’s get started.

  about 2 months ago

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