Versatile 0.01Hz to 100KHz Analogue Function Generator XR-2206

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Preface

Fig. 1 - Front view of the analogue function generator

Fig. 1 – Front view of the analogue function generator

The XR-2206 from Exar© is a great IC because, with a few components, it makes it possible to build a circuit that generates analogically various waveforms with a frequency from 0.01Hz to 100MHz. This capability allows you to build quite easily a function generator useful to test audio devices and all the circuits that require a low frequency input.

By exploiting the characteristics of the IC, I provided the PCB with two outputs: one suitable for testing analogue circuits, one for testing digital ones.

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Multi-Frequency Second-Order Active Crossover for Subwoofers NE5532

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Preface

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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Compact 2A 0-30V Variable Switching Power Supply with Current Control L296

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Preface

Fig.1 – The compact 2A 0-30V variable switching power supply with current control

Fig.1 – The switching PSU

This is the PCB I used to test all my projects.

When I drew it, I took the cue from the project published on electroniq.net (I hope the attribution is made to the right author because I found many clones on the internet). I changed something on that schematic making the improvements I thought were right also in order to try to use the components I already had available.

To be honest, what makes the project so good is not this specific schematic. That is nothing more than an elaboration of some “typical applications” suggested on the L296‘s data sheet, but the IC itself.

The l296 switching regulator requires very few external components and the current limiter is already inside it (make sure to use the L296P to take the advantage of this function).

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Phase shifter for bridging two amps NE5532

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Preface

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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Precise Thermometer with 3½ Digits LCD Display ICL7106 AD590

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Go to the project BP003 if you want to add a bi-colour LED backlight and a power supply board on the thermometer. In addition, an useful video clip is available there to watch the thermometer in action.

Preface

Fig.1 – The digital thermometer's LCD display in action

Fig.1 – The digital thermometer in action

I wanted to build this project because I needed a thermometer in my house, but also, because I wanted to have the occasion to use a LCD display for the first time.

I have always been fascinated by LCDs. Their capability to make numbers, letters and drawings on a glass plate is something magic. Thanks to this project I learnt a bit more about them and I discovered the tricks of the wizardry. Despite this, and even if the LCD displays have become obsolete, I still think they are the result of an amazing technology.

I chose to use the ICL7106 as the driver for the LCD display. This specific IC by Intersil, has also inside an A/D converter necessary to “transform” the analogue signal generated by the temperature transducer into a digital one. For practical reasons, I decided to split the project in two different sections, and then, in two different boards: one for the LCD display and another one for the ICL7106 IC.

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Dual 3A DC-DC Voltage Regulated Power Supply LM317 LM337 BD139 BD140 TIP35C TIP36C

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Preface

Fig.1 – The dual 3A DC-DC voltage regulated Power Supply

Fig.1 – The dual 3A DC-DC voltage regulated PSU

Initially I built this PCB because I was fed up to hear the annoying low frequency noise from the speakers of an old amplifier. The issue came from the power supply that clearly wasn’t very good. The residual 50Hz signal from the AC line, technically called ripple, was so high that it generated an awful fixed background sound. By installing this PCB, after the existing PSU, I solved my issue.

Later, I decided to use the PCB as a general power supply to test my projects. It has always worked perfectly even if setting the voltage output by trimmers was not very comfortable. For that reason, if you are thinking of building it for that purpose, I suggest to substitute the trimmers with potentiometers by connecting them with wires to the board or, better, redraw the whole PCB mask.
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Amazingly Small and High Performance Audio Power Amplifier LM3886

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Preface

Fig.1 - The amazingly small and high performance audio power amplifier with LM3886

Fig.1 – The audio power amplifier with LM3886

By using the LM3886 it is possible to build a very small PCB but with the performance of the more complex and expensive commercial power audio amplifiers. Of course I’m not comparing this amplifier with some super ones available in the market, but you’ll remain amazingly surprised listening to how good it sounds.

The basic configuration suggested by the LM3886‘s data sheet works well already but it is possible to change something to make it sound better. For instance adding a few extra components to filter the signals more carefully, or, since a handful of components are necessary, it might be worth spending a little more money to buy some high quality ones.

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