Power supply for Buck dc-dc

PLUS - you have NO SAFETY ISOLATION !!!!

For most applications, such a set up would be LETHAL !!

Forget it.

..... Phil

Oi. Wrong in so many ways. Where should we start?

The short answer is, given what you know, don't even try. Learn more about electronics first, then start playing with power from the wall when you're not going to kill yourself, burn your house down, or shock your kids silly.

If you don't understand why you can't connect your equipment straight to the wall power without isolation, then you need to learn more about electronics and about how houses are wired for power before you can safely proceed to play with 120V. While it isn't always instantly LETHAL!!!, getting a shock from 120V always hurts a lot, it _can_ kill you on a bad day, and there's a lot of ways that you can build your equipment so that it doesn't kill you or your loved ones, but still burns down your house.

Get yourself a copy of the ARRL manual. They've got whole chapters in there on power supply design, electric safety, how houses in North America are wired, and all that useful stuff. Then READ IT. If you don't feel you understand what it says, don't mess around with 120V -- just find a wall-wart that delivers what you need, and be happy.

Yesterday I took my digital multimeter, insert a 1N4007 diode in power's home, and I got 52Vdc from that !

Tim is right. When you understand why you measure 52VDC with your digital multimeter you'll be in much safer position to move forward.

supply ?

d3

o rectify

Is there any way to bypass transformer´s usage to power this buck ? It´s only for school work, not for real usage...

wer

iode

ks.

en

ns

home, and I got 52Vdc from that !- Hide quoted text -

That makes no sense to me. Have you been zapped by 120 Vac yet? Keep one hand in your pocket. You can buy a nice linear power supply from Mastek ~50V @3A for a bit more than $100.

George H.

On a sunny day (Fri, 11 Jan 2013 06:41:26 -0800 (PST)) it happened snipped-for-privacy@gmail.com wrote in :

No. And if you single phase rectify 120V AC you still get 120 /2 * sqrt(2) = 85 V DC peak. Add some for main tolerances. And you would not be insolated form mains.

On a sunny day (Fri, 11 Jan 2013 09:56:17 -0600) it happened John Fields wrote in :

DC peak.

Oops! I must be getting old.... Thanks for the correction... :-)

wer supply ?

And what about this ? Vrms=Vpeak/2 Vdc=Vpeak/Pi

supply ?

The RMS voltage of a waveform is the DC voltage which would heat a load the same amount as the waveform under question.

For example, since Vrms = Vpeak/2 for a half-wave rectified sine wave, that signal, with an amplitude of 2 volts, would heat a load the same amount as 1 volt, DC would.

The average DC is the number you'd get if you took a great number of equally time-spaced voltage samples from the start of one half-sine pulse to the start of the next, added them all up, and then divided that sum by the number of samples.

In the end, that quotient would be equal to Vdc = Vpeak/pi.

DC peak.

home, and I got 52Vdc from that !- Hide quoted text -

Wall warts are cheaper and even safer. 5V@2A, or so, won't get a newb in too much trouble and will be quite useful while learning.

Somewhere I have a 230VAC theraputic lamp/heater - it used to have a UV ray tube and used a pair of heater bars with combined rating of 115VAC to act as ballast for the UV tube and provide Theraputic IR rays. When the UV tube is not required (or missing) the heater bars are fed by a hefty rectifier diode, by clipping the half cycles; the power delivered to the heater bars is halved.

Unfortunately, with a buck converter; it doesn't work like that - the input filter/reservoir electrolytic will charge to 1.414 x 110V.

Of course with a buck regulator the transistor is in series with the load, so when the severely over-volted transistor fails short-circuit - the load should provide a short, but spectacular fireworks display.

supply ?

b54d3

to rectify

No! Unsafe. You will destroy the power supply. It may burn up or explode. It may maim or kill you.

Is this clear enough?

Tim warned you off, you are not fit to make a guess on this.