LM317 Constant Current Calculator, Tool

Here is a handy LM317 constant current calculator/tool. It allows you to quickly calculate the set resistor and the heatsink (is needed).

LM317_constant_current Read More »

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Here is my circuit adopting the famous LME49811 amplifier front-end and ThermalTrakTM

transistors. This one is a rather conventional topology but implementing some tricks to improve the performance. Read More »

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Simple JFET Preamp

A JFET preamp for beginners. Simple yet elegant. Low noise.

The following is an example for a very simple and high quality JFET preamp. You can use this to amplify a very low signal sources. FET transistors are usually not used independently in preamplifiers. In most of the cases they are paired with bipolar transistors. Read More »

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Soft start, Speaker Protection by Audio Workshop

Soft start. Speaker Protection. Speaker Delay

Soft start. Speaker Protection. Speaker Delay

We have completed this module this week. It is a custom build by order of a customer. The module has many specific functions. It can be used for speaker protection, speaker delay, toroid soft start and others. Read More »

Posted in Design, High-end, Power supplies, Uncategorized | 4 Responses

Art For Engineers


Well mandala-1we all like and enjoy beautiful things of life. Art is a fine example. Engineers however are a kind of  different animals. They enjoy looking at bizarre things. I do as well. What you see on the right is a fine example. A “painting” made out of electronic elements. Almost every possible type of electronic device is used and I think it’s amazing.

No deep thoughts about this. I’m not an art expert. Some might find it ugly, some might find it strange or whatever. I just wanted to share this with everybody.

If you like this be sure to check out this website.






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Original and Reproduced Audio

Define Original and Reproduced musical and audio contents

reproduced_soundIn general we listen to musical performances in two basic ways. The first one involves an actual attending to real live music events (a concert, an opera, ballet music festival etc.). In this case the musical content we perceive is called ORIGINAL musical (audio) content (OAC), unlike the REPRODUCED musical (audio) content (RAC), which we perceive by using electronic and electro-acoustic devices. For the purpose of this article I will use the terms original audio content and reproduced audio content.

The reproduced musical contents are generally divided by two groups depending on the time we listen to them.


The first type is the so called synchronous audio contents. Those we get when we listen to any LIVE broadcasting over the TV, radio and live internet streams. This type of musical content is characterized by the fact that it occurs simultaneously with its original prototype but at a different place. Read More »

Posted in Acoustics, Equipment, High-end, MUSIC, Performance | Leave a comment

Unico CD Primo. High Fidelity of High Pleasantness?

unico_cd_primoSo it was a pleasant weekend. Just a few folks gathered together to listen to some good music. Well not only. It’s always about listening to something in particular and test it against something else. In this case one of the guys had brought his beloved CD player – the Unico CD Primo by Unison Research.

Well I had to say that I was rather suspicious about this testing. The first thing is that this CD player has a really good looking tube output stage. Having noticed that it was clear that this fellow has nothing to do with the neutral and transparent sound. However I kept my thoughts to me and we all sat down and listened. Read More »

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Testing Power Supplies

Here is a very interesting video on how to test power supplies. There are four parts actually. The series of videos focus on using DC-DC buck and step-up power supplies by Texas Instruments. The techniques described however are applicable to any other manufacturer.

The first part shows some power supply testing fundamentals like setup overview, necessary equipment, proper connections etc.

Read More »

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Grounding System In Power Amplifiers

Here is a very good schematic showing a tipical power amplifier grounding system. I have tried it ina many of my projects and it works every time. No hum, no ground loops no noise. Dead silent. Of course a proper power supply routing on the main PCB is critical. If done properly some very very high performance could be achieved.

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Amplifiers, Oscillation, Stability. BJT CIrcuits

One of the more troubling aspects of analog circuit design is amplifiers that oscillate when they are not supposed to. Engineers commonly respond to spurious oscillations with empirical efforts to defeat the instability, by throwing small-value resistors, ferrite beads, and bypass capacitors at the problem (whether in a hardware prototype or circuit simulation), hoping it will go away. Perhaps these kludged circuits stop oscillating, but then the performance has been degraded. Or perhaps occasional production units oscillate. What is a circuit designer to do?

The answer, of course, is to understand why the circuit oscillates. There is always a rational, underlying cause for annoyingly unwanted sinusoids, and finding it can lead not only to a stable circuit, but also a performance-optimized circuit. Not only can the oscillation be modeled and its compensation designed, the margin of stability can also be estimated so that you can know how far from oscillation the circuit design is.

In Part 1 we examine causes and solutions for discrete BJT (bipolar junction transistor) amplifier circuit oscillation. The principles carry over to FETs fairly directly. We will look at two cases: in the first parasitic resonance is the cause; in the second the little-known effect of high-frequency impedance gyration explains why capacitively-loaded emitter followers often oscillate.

Why Circuits Oscillate Spuriously, Part 1: BJT Circuits by Dennis L Feucht – >>>LINK<<<


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