Posted on Friday, February 18, 2011 • Category: PIC
For a long time I needed a good programmer pussy, even if it is programming, so from time to time the application gets where it is used. So I decided to build the programmer. I chose between a couple of projects from different authors, but eventually won PICkit2. Microchip released the schema directly in the user manual for the programmer. On the Internet there are multiple versions of the programmer, it's usually cropped version of the log analyzer features, UART terminal, etc., 12V inverter is a modified version of it and control the MOSFETs, unlike bipolar transistors used in the original design. And it also showed that becomes due to the switching inductance feta leave. Finally, I chose to use the original scheme, although it is quite complicated and the parts used in our country can not normally buy, but my problems with finding parts easily solved. I bought a transistor, the 16F2550 PIC and a few other things, resistors and fry the rest I bought from "us". The price is pretty high, unfortunately, moving it around and 600CZK, the main prize and two processor makes the EEPROM. Below we describe the involvement and put into operation.
Posted on Tuesday, February 15, 2011 • Category: Amplifiers
After I built several LM3875 and LM3886 gainclone amplifiers, I was totally impressed by their audiophile sound quality. My design goal is to create a audio power amplifier that can deliver 300W into my 4-ohm DIY speaker with low distortion. I want it to produce deep, tight and punchy bass while keeping the excellent mids and highs from my other gainclones. My design uses a PCB to hold 3 paralleled 3886s (i.e. PA150), and then I use the DRV134 to bridge 2 of the PA150 PCB boards. The function of DRV134 is to convert the un-balanced input signal to a balanced signal, so that the non-inverted signal is fed to one PA150, and the inverted signal is fed the another PA150. One of the PA150 is connected to the speaker's positive input, and the other PA150 is connected to the speaker's negative input. Because of this push-pull configuration, the total gain of the amplifier is doubled. Each PA150 has a gain of 20, so the gain of the BPA300 is 40.
Posted on Saturday, February 12, 2011 • Category: Arduino
This Arduino can be used for old school prototyping as well. Just use it as a standard ATmega8 and program it with the ISP connector. And it is one of the cheapest Arduino boards, that you can get. Arduino is a great prototyping platform and most of you probably know already about it. If not, check out the Arduino pages and the Arduino playground and dive into it.
Posted on Thursday, February 10, 2011 • Category: Amplifiers
400W Stereo Audio Amplifier based on the original Marshall Leach involvement, but has made some improvements. Regarding the power supply voltage to the +-75V. VC comparing the performance of the modified Leach 700W/2R on one common board of both channels, as well as protection and control circuits for the fans. Compared to the 700W version a bit different in wiring. Because some things in the 700W version is completely tightened to perfection.
Posted on Wednesday, February 9, 2011 • Category: CNC Milling Devices
The electronics of a CNC machine is a simple but often confusing matter. In the picture (down) is shown the schema of a full system of four axes. Sometimes the breakout board is not present and the parallel port connected directly to the controllers. The main advantage of using single stepper controllers enable the user to connect different motors even in a mixed configuration (unipolar or bipolar steppers) tuning the CNC machine performances to the job to be done. A common and simple solution is the use of a board where the optoisolator (if any) and the controller/drivers are present in the same board, all-in-one. This solution allow a general quicker connection and a simple wiring but force the use of three or four identical (or similar) stepper motors.
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