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Printed Circuit Board (PCB) Technologies

The term circuit technology usually refers to the various techniques used in the manufacture of electrical circuits. A large number of devices that are used today make use of printed circuit boards (PCBs). These devices provide mechanical support for the various components present within the given device and the components’ electrical connections. The electrical connections present on the PCB are made out of copper sheets laminated on a non-conducting material. Initially, a large copper sheet is laminated on the board, and then the sections that are not required are removed. Various techniques are used for the removal of unwanted copper. Some of them are: Silk Screen Printing: In this technique, an etching resistant ink is applied to those required areas, and the remaining part is etched off. Photoengraving: Here, a photomask of the circuit required is prepared using the desired software, and then it is applied onto the blank PCB. After this, the portions that are not required are etched off. PCB Milling: In this technique, a mechanical milling system that can work on 2 or 3 dimensions is used to remove the copper. The milling system is controlled by software. In some other techniques only the required copper is…

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Eagle CAD PCB footprints for audio processors TDA7313 and TDA7315

TDA7313 and TDA7315 are digital controlled audio processors used in applications where digital control of audio is needed. TDA7313 and TDA7315 are pretty the same just TDA7313 is more complex by having 3 stereo input channels and two outputs (front and rare). Both chips have volume control (step=1.25dB), tone (bass and treble) balance, independent faders for each output processor. Also, there is loudness functionality. TDA7313 and TDA7315 have low distortion and low noise, making them ideal for quality audio applications for car audio and Hi-FI systems. MCU can control both chips via the I2C(TWI) protocol. This makes it easy to interface microcontrollers with additional features like LCD, buttons. Or control directly from PC using RS232 or another interface. Both chips can be found in DIP or SO packages. Here are Eagle libraries of both digital audio processors that I have made. tda7315.zip(2kB) tda7313.zip(2kB) I have intent to make a control board with TDA7315 with LCD and button control using an Atmega8 microcontroller.

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PCB construction methods for embedded controllers

The most common method is of constructing embedded controller systems is a Printed Circuit Board (PCB). All electronics know that simple PCB is constructed of insulating material like epoxy impregnated glass cloth with a thin copper sheet(s) on one or both sides. There are many conflicts about requirements on how to design interconnection patterns of PCB. But the main purpose for all is to make PCB reliable, effective and producible. If the circuit operates at a low speed, requirements are not as strict as for high-frequency devices where the parasitic effect cannot be ignored. Each PCB stray has its own resistance, capacitance, and inductance. These are the main effect that distorts the signals.

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Desoldering Atmega128 using a lighter

I heard about this method and decided to try it with my board. I needed to replace the Atmega128 chip but didn’t have hot air solder for desoldering IC. I tried this weird desoldering technique, and I can say that I was satisfied. Tracks and other parts weren’t damaged. The Atmega128 board is working again as before.

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PCB Exposure using UV light LED box

I came across this interesting project. The guy decided to make a UV PCB exposure box made of UV light LEDs. The main reason why he used LED was the power dissipation and compactness. Assuming that one UV tube would take about 6W while one UV LED would take about (20mAx3.2V=64mW). Most of that energy UV tubes dissipate as heat energy. So he took: 54 x UV LEDs of 400nm (6000 – 7000 mcd) – 100 units in Ebay costed 12€;18 x 68ohms resistors 1/4W – 0,36 €;1 connector – 0.50€;1 electrolytic condenser of 2200uF – 30v;1 Eurocard Plate 100×160 about 5 € ;

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Place electronics parts correctly on PCB

Let’s go through a few examples of how to place electronic parts correctly on the PCB board. SMD electronic parts, especially if the lead pitch is above 1 mm, then placement of leads has to be symmetrical on copper planes: If IC has a smaller lead pitch like 0.5 – 0.8mm, positioning by hand becomes harder. Sometimes it is recommended to use special glue to fix SMD parts before soldering. DIP electronic parts must be soldered as close to the PCB board as possible to make them stand stable and avoid heat resistance.

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Generic PCB design guidelines

How repeatedly make good PCB? Many hobbyists face this issue every time they are prototyping their ideas. Designing the PCB layout (it doesn’t matter it is a through-hole or surface mount) may be a tricky task, especially when dealing with dimensions like 0.2mm tracks or 0.5mm surface-mount pitches. A laser printer, plotting, or other similar transfer technologies can’t deal with such dimensions. After I have tried the photographic method of PCB artwork transfer, I don’t even want to touch the Iron and laser printer. Using photosensitive laminate and single transparent media, I can repeatedly make any number of PCBs. The benefits of using photographic methods are as follows:

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PCB Etcher

After UV-80 was built, there was a thought about automatic PCB Etcher with autonomous Heater and bubble machine. This project is hanging in the prefinished phase, but it does a job. It was used to etch several PCBs. As this etcher is supposed to be used for making PCBs using photosensitive technology, the controller is supposed to control both = the heater of the etching tank and the developer’s heater. As Sensors, there are used AD7416 digital temperature sensors. I decided to publish this small project, as this is not clear when it will be finished. When it is, I will update this article. There is a little dirty drawing with dimensions: The dimensions are as follows 215x275x30 exterior. The inner volume is smaller as glass is 4mm thick. So the overall volume is less than 1,2 liter. It is an ideal volume to use one bag of ammonium persulphate or 250 grams of FeCl3. The glass plates are glued with aqua silicone. Sides are strengthened with aluminum profiles (not necessary if you have skills of glueing aquariums).

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Ultraviolet light source UV-80 for PCB exposure

One of the more advanced PCB manufacturing methods is exposing laminate copper boards covered by a photo resistive layer through the mask. Using UV light in manufacturing PCB’s has many benefits according to other methods: you can get thin tracks like 0.2mm. You couldn’t do this using other home techniques like laser printers or hand artwork; another advantage is that this method gives a clean image – smooth edges of PCB tracks. Little bit effort and you can compare results to commercial products. And of course, the third benefit is speed and multiple replications of your boards by using the same mask. This article is described in the manufacturing of an automatic ultraviolet light source exposure box. Parts for UV box Case with organic glassPanelUV lamps ballasts and startersController Case Case is made of 5mm wood board wired with screws. Making a control panel The Control panel consists of two parts: Power control and Automatic control.A POWER switch is used to turn the on/off the power of the UV box. Green LED indicates the ON. MANUAL/AUTOMATIC switch is used to power l the UV lamps manually or automatically. Switches UPSIDE and UNDERSIDE are used to enable upper and lower lamps…

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