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It has been a while since I did anything really crazy in DIY and had it work out far above my expectations. Such is the case for the Mini Blocks. I had a lot of extra parts lying around (really a huge amount of them) and tried to figure out what I could build. Two small chassis about 5 inches by 9 inches by 2 inches (12.5 X 22.5 X 5 cm) were just begging for a project. They are just the right size for lots of things. I first thought of a pair of SET amps. But since I didn’t have any suitable single ended output transformers I nixed that idea. A preamp perhaps could be built on one of the chassis. Since I have many preamplifiers now that didn’t really get the nod either. A pair of small push-pull amplifiers was next on the list. Maybe, but I have so many amps now that it doesn’t make sense either. Since this hobby doesn’t always have to make sense, that is what I built. [ ]

Dual Operational Amplifiers AN4558 Datasheet for AN4558: Download

  Overview  The AN4250, the AN4250S, and the AN6593 are  single operational amplifiers which can be operated  with very low power consumption. Moreover, they have  wide range (±1V to±18V)of supply voltage, and  electrical characteristics such as power consumption  and input bias current can be programmed according  to the current value set by outer resistor. T hey are suitable for applications to various  electronic circuits such as portable electronic  equipments operated by the battery. Features Wide supply voltage rang (±1V to ±18V) Electrical characteristics programmable by set current Phase compensation circuit built in Output short-circuit protection Offset null Circuit diagram:  Low Power Consumption Operational Amplifiers Pin Datasheet for  AN4250: Download

Non-Switching Amplifiers Most of the distortion in Class-B is crossover distortion, and results from gain changes in the output stage as the power devices turn on and off. Several researchers have attempted to avoid this by ensuring that each device is clamped to pass a certain minimum current at all times. This approach has certainly been exploited commercially, but few technical details have been published. It is not intuitively obvious (to me, anyway) that stopping the diminishing device current in its tracks will give less crossover distortion . Current-Drive Amplifiers Almost all power amplifiers aspire to be voltage sources of zero output impedance. This minimizes frequency-response variations caused by the peaks and dips of the impedance curve, and gives a universal amplifier that can drive any loudspeaker directly. The opposite approach is an amplifier with a suffi ciently high output impedance to act as a constant-current source. This eliminates so...

1. Class A Power Amplifiers The purpose of class A bias is to make the amplifier relatively free from distortion by keeping the  signal waveform out of the region between 0V and about 0.6V where the transistor’s input  characteristic is non linear. Class A design produces good linear amplifiers, but are wasteful of  power. The output power they produce is theoretically 50%, but practically only about 25 to 30%,  compared with the DC power they consume from the power supply. Class A power amplifiers use the biasing method illustrated in Fig. 5.2.1. This method causes a standing bias current to be flowing during the whole waveform cycle, and even when no signal is being amplified. The standing bias current (the Quiescent Current) is sufficient to make the collector voltage fall to half the supply voltage, and therefore power (P = I C x V CC /2) is being dissipated by the transistor whether any signal is being amplified or not. This was not a great problem in class A v...