EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: BiOzZ on April 03, 2013, 04:46:47 am
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Well i needed awhile ago a simple 35V supply for a random number generator inside my computer so i whipped this up
(http://i.imgur.com/ftemEL4l.png) (http://imgur.com/ftemEL4)
(http://i.imgur.com/tNZeCap.jpg)
i just needed 35V so i did no calculations and detuned the hell out of this and still got well over 80v out of this damn thing!
works quite simply! the 555 generates the boost and the 393 drives the reset pin low when you get above the set voltage!
the knob i put on for kicks i could have used a simple threw hole pot but than i could not fiddle with it!
NOTE: I HAVE NO IDEA HOW R9 GOT IN THERE! DONT USE IT!!!
it goes inside an all metal snus container and probably is loaded with noise and im not sure on the output ... its not driving any real load in its purpose
im a huge fan of the 555 and the 393 ... yes i have some SMPS controllers but why? i have a 555 and a 393! you can go to the moon with a 555 and a 393!!!
hope this was useful for yall!
PS: i use a small 160W PSU inside my computer just for lights, fans and the little addons so its separated from the rest of the PC PSUs ... im not sure how well this would work on the main supply ...
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How about using the other comparator in the 393 to make a controllable oscillator to replace the 555?
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not the first time i've seen this done, a bit of lab gear i have uses a 556 using the second 555 in a similar fashion to drive and regulate pretty much all the voltage rails,
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If you're going do to regulated boost with a 555, the CV pin is your friend. Don't even need the 393, just a transistor and a few resistors.
Also, have you stuck a scope on the output? $5 says it's unstable.
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I have done clock ( the ticking kind) oscillators using a 555. Was at least accurate to make an hour meter that turned over on the hour.
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too answer many of your questions at once i wanted to whip this up quickly and space was not a concern so i did not take time to calculate out a relaxation occ or calculate out what i would need to send in to the CV or other workarounds like a vref and stuff ... just pulled my 2 favorite parts from the parts bin and had at it right on the perf!
@Rerouter, i would not doubt this was done before but using the 555s built in comparator + latch on the 556 is quite smart!
@SeanB, its a wonderful little thing!
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It worked well, though the little audio transformer i used did not really like running at 400Hz to make a 26VAC rail to drive the clock mechanism. Those clock mechs were nice, still have one around somewhere.