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Posts by wakibaki

What's in a PIC?   It's not really possible to discuss PIC utilization without having some kind of idea of what a PIC is.   Programming is full of specialised concepts and has its own vocabulary. It really helps to understand a few of these before launching into the business of writing a program, but I'll try to keep this to a minimum and stick to what is really necessary.   A PIC is what is sometimes called a microcontroller. It's the essentials of a small...
Hi, Mike.   Nice to hear from you.   One of the hardest things when talking 'into the blind' like this, is trying to remember the things that I found puzzling and needed to know when I was first learning the subject and making sure that I don't skip over necessary details because I've become so familiar with them.   So just give me a poke if you think that I'm running on a bit too quickly, or, on the other hand, if I start to labour the point a bit and get...
A little while back I made a passing remark about writing a programming example for Microchip PIC.   Avro_Arrow said at the time that he would be interested if I took it on. I've been a bit remiss in keeping up my discrete amplifier co-operative design effort with him, so I'm going to write this tutorial. With luck, I'll have at least one reader.   The first thing we're going to build is a simple panel (volt) meter with digital readout. This can readily be...
Here's the new PCB with routing completed, showing grounding highlighted.         This shows the chassis in outline with transformer positioning and 4-way switch mounting arrangement. Some of the track spacings are a bit tight, and the whole thing needs a bit of fine tuning, but it shows that the routing is possible. Regulators and CCS transistors will be mounted off-board on the chassis for heatsinking.     Oh, I'll be able to fabricate this at...
  drugs r bad, m'kay? you shouldn't do drugs, m'kay? cuz if u do, u r bad, m'kay?    all metals r equal, but some r more equal than others, m'kay?   Recall that there is a fundamental difference between metals. All are conductors, but some are magnetic (ferromagnetic), like iron, steel, cobalt and nickel, others, like aluminium and copper are not.   Consequently you may find a copper electrostatic screen in a transformer to prevent capacitive coupling between windings,...
Good luck. Let us know how you get on...   w
Here's a BOM with costing, major component prices are accurate, small component prices may vary from those shown. You can probably save a few Euros by being careful. I have simply marked generic components 'ebay supplier'     Category Quantity Reference Value Price (Euro) Total Source Resistors 2 R1,R2 5k1 0.1 0.2 ebay...
You should have no trouble obtaining the parts, I see you live in Portugal, I am in the UK. I sourced the majority of them from a German supplier, tube-town.net, they deal in Euros, the rest can be obtained from ebay.   w
Overall distortion (distortion at the transformer output) rose from ~1.425% to ~1.48% when I replaced the diode with a resistor.   This is with the amplifier driven very close to grid current in the second stage, which is the limiting condition governing the power which can be obtained.   Distortion at the output of the first stage is 0.775% with the diode, rising to 0.79% with the resistor.   These are the figures automatically calculated by the program. I...
Yes, you could run the amplifier in the link from the battery in the other link, the reduced supply voltage will not be a big problem, you will get a bit less volume, in fact it may actually make things easier as regards heat.   As you can see though, most people (including me) have concerns about the amplifier overheating, resin is a pretty good thermal insulator.   That said, that particular amplifier probably has the best chance of surviving the experience,...
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