Viable Linear PSU

Just a simple AC-DC supply with voltage regulation. Ripple of less than 2mV and efficiency...well it depends whether you're trying to draw 5V@2A from 40V@2A or let's say 30V@2A from 40V@2A so let's assume an average of 40% efficiency but reaching as low as 10% therefore a lot of power gets dissipated as heat. That means all power transistors should have large heatsinks and the 2x100mohm resistors should be wirewound with a big power rating. Put the large AC-DC filters in the equation and you get that compactness is out of the question. The reverse junction diode is for inductive load protection.This circuit per se could be used in a fixed manner (like in amplifiers) where you'll need a fixed voltage all the time and the position and the attachment of the PSU will be permanent. The idea of this is to minimize the possibility of a short circuit which this PSU cannot withstand (no breakers or current limiters). If you wish to use it as a bench power supply you'll need to implement several other sub-circuits like a circuit breaker or a current limiter to prevent the devastating effect of a short circuit on the power transistors and the regulator in general. When compared with switching power supplies linear ones have a few advantages like: - Unconditionally stable - no argument there - Simplicity - just a rectifier+a regulator in opposed to many many circuitry in the switching ones. - Robustness - just to clarify i mean Linear supplies are more adaptive to short circuits load changes negative voltages from inductive loads etc than switching power supplies - Cheaper to make and attend to - Cause less problems of any kind - For instance switching supplies can sometimes feedback noise into the mains due to the ground loop phenomenon which causes interference in some other devices like introducing an audible hum in amplifiers causes glitches in digital devices and many many other problems. Nonetheless it has certain disadvantes over switching supplies like... Switching PSU advantages: - Efficiency - theoretically 99% but is around 90% in most cases - Compactness- switching supplies have higher efficiency levels which means they dissipate very little heat which makes them more compact not having to use large heatsinks. Also they require less filtering than 120Hz (in linear)

published 10 years ago