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  • Author Author: Robert Peter Oakes
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The Modular Bench Power Supply ++ - Power Output Stages

Robert Peter Oakes

In previous videos we have looked at the different modules that make up a typical bench power supply, in this post we will continue that trend and look at the Power Stage of typical power supply, evaluating different components (NPN, PNP, N Chan and P Chan MOSFETs), how there controlled and a bit of practical how-to

 

This is a link back to the main PSU blog : http://www.element14.com/community/groups/test-and-measurement/blog/2014/09/15/the-modular-bench-power-system-the-essential-diy-build-for-every-ee-student-and-old-timer-alike

 

Sorry its long (I did shorten it... honest image ) and is the first of two, this one covers a basic intro to the devices and detail of the NPN and PNP BJTs

 

and here is the next video covering the MOSFETS

  • in reply to jw0752

    Well I have been basically just using what I have as samples and in the spares bucket so far, as will ponder on that and give a heads up as soon as I know

     

    something that can go to 30 or more volts, output close to rail to rail and perhaps low noise, does not have to be instrumentation amp but if you have some then that would probably work

     

    The next video will probably be about sense and precision resistors, Vishay Precision Group have ben extremely generous to me and have been working with me to find some great parts to use in the tutorials so I want to show them off, they sent me some samples to use of various tolerances and types down to 0.01% and Kelvin Connection sense resistors up to several watts rating at 1% and 0.5%, all low drift into the few PPM , admittedly some are more expensive than you may want to use for a basic PSU but if your going for the precision end then worth a look, this video will be very exciting to make and hopefully very informative to watch

     

    The power input video is still waiting on a couple of parts arriving so is a few weeks away but there is plenty to do in the mean time so the next PSU specific one will probably be about putting all the parts together or the plan to,  so I will make a few suggestions on parts for sure ahead of time

     

    Also need a session on heat dissipation, I alluded to massive power that may need dissipating with low voltage output and high currents and as a viewer rightly pointed out, the 300W N Channel MOSFET I was showing actually needs a negative temperature heat sink if it is to be used on its own, if you double it up (2 MOSFETS or 150W each ), then an air cooled big one will work but on its own.... no way (Makes me wonder how they even came up with the rating, must have been with active cooling)

  • Hi Peter, Would you mind telling me what are your recommended OP AMPS going to be for use in this project.. I would like to get a few in so I can start experimenting with them.

    Thanks John

  • Hi Peter, I enjoyed it and the time went by with out me noticing it. I am not sure you could condense it more and still give all of your audience the information that is needed. The subject was very close to what we were talking about earlier with my question. Thanks again for your tutorials.

    John

  • Good job Peter.

     

    It has been a long time since I went through transistor theory.

     

    You bring back long buried memories.

     

    DAB