Multi-Frequency Second-Order Active Crossover for Subwoofers NE5532


Fig.1 – The multi-frequency second-order active crossover for subwoofers

Fig.1 – The multi-frequency active crossover

The project offers an universal solution that allows you to find and set the best cutoff frequency for an audio system’s subwoofer with no special equipment. Beyond this, in my opinion, practical listening is the best way to compare audio configurations and devices: charts, parameters and calcs are very important but they may not be respected when put into practice.

This crossover gives you the possibility to set six different cutoff frequencies: 63Hz, 80Hz, 100Hz, 125Hz, 160Hz and 200Hz. The right selection is the one that will make your audio system sound better.

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Intelligent bi-colour backlit LCD display’s thermometer ICL7106 PIC16F84A LM324 74HC148


Fig.1 - The thermometer with the green backlight

Fig.1 – The thermometer with the green backlight

What I’m getting ready to explain below, is an original solution I adopted to backlight the thermometer’s project SP0003. Thanks to this, I solved quite easily the main difficulty that consists in generating an even illuminated background to the LCD display using some common LEDs.

At that time, I was also learning how to use the microcontrollers and I wished to make my first real project (and not only on a breadboard) with the PIC16F84A. I programmed the µC for changing the backlight’s brightness according to the room’s light intensity because it could be annoying in the dark, or insufficient in the opposite condition. I also thought that it could be nice switching the LCD backlight colour by pressing a push button.

To complete the project, I inserted a power supply to the thermometer capable of accepting a wide range of DC or AC voltage.

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Phase shifter for bridging two amps NE5532


Fig.1 – The stereo version of the phase shifter for bridging two amps

Fig.1 – The stereo version of the phase shifter

As declared on the last post, I have published a very recent project, built after the andy-progetti website’s birth.

This circuitry is an elementary phase shifter but I think it represents the best solution for bridging two amplifiers. I don’t know if you already know the theory of bridged amplifiers, otherwise, on the Wikipedia’s website, you can find the main information about it.

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