All valve rectifiers also impose an upper limit on the capacitance following the rectifier, and that usually means that the filter cap is far too small to provide acceptable filtering. For example, a 5AR4 has a typical plate resistance of around 50 ohms at 25mA plate current, and a silicon diode in series with a 50 ohm resistor will give virtually identical results. This is replicated easily by using resistors in series with silicon diodes, of a value similar to that found in the valve data sheet. Contrary to the firmly held beliefs of some, they have exactly zero sonic benefit in any design, but there are people who (for reasons that I can't determine) prefer the power supply to sag under heavy load. One omission that will be apparent to many readers is any reference to valve (vacuum tube) rectifiers. This depends on the type of rectifier used, and is described in more detail further below. If the voltage is increased, you simply need to ensure the diodes are rated for the worst case PIV (peak inverse voltage) to which they will be subjected. Most of the general principles described can be translated to higher or lower voltage or current with no change to the basic parameters. The purpose of this article is to explain the terminology used, traps and pitfalls, and give some insight by way of a few practical examples. These linear supplies should not create any problems for anyone, because they are so simple, right? Wrong! They appear simple, but there are many inter-related factors that should be considered before just embarking on your next masterpiece. This specifically excludes switchmode supplies, which are a great deal more complex. I do not intend to deal with 'esoteric' designs with interesting names, but the simple, unregulated linear power supply that is still the mainstay of audio power amplifiers. ![]() Power supplies are needed for every type of amplifier (or any other electronic equipment for that matter) we will ever use. Having searched the Web for reference material (and found very little!), this would appear to be the definitive article on the design of a 'simple' linear power supply for a power amplifier. 5.2 Increasing Capacitance / Transformer Size.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |