diode

街で見かけて最近のランドセルはすごくかっこいい色をしているのだなあと思いました

Another holiday has come and gone | Bob Hicok

It’s shoot an arrow 
into your ceiling day, I’m out of arrows, 
I go to the neighbors 
to borrow a cup of arrows, they’re making love 
on the floor doggy style, in that 
she barks then he barks 
at her barking, then its over 
and they circle in front of the door 
to be let out, we’re trapped, 
I tell my lover later 
on the phone, do you mean us, she asks, I lie 
and tell her no, I mean every other person 
but us, we are free, we 
are entirely wings and little bits 
of fog and the open windows 
of speeding cars and Carmen 
at the end, when the performers 
take their bows to the rush of air 
from between our palms, forgetting 
she is deaf, that she’s heard nothing 
I’ve said, that this is a poem, 
that I am out of arrows and more 
importantly out of bows

The Things I Do When I Am Not Doing You

for Elizabeth

I Google my name and your name. I wrote another poem that started like that but fuck it, I like this poem better. I Google swift touch. I Google Swiffer Wet Jet. There are coupons on the website. These coupons make the Swiffer Wet Jet affordable. I will buy two in case one breaks down. I will clean my floors for you. I will clean myself after I clean my floors. This is how you will know I love you. I Google why does chocolate melt? and then I lick my fingers. I Google licking fingers and find out it is a Swedish independent record label. I Google Swedish Fish and get hungry. Swedish Fish are like gummy bears but they are all red and have gills. Gummy bears don’t have gills and some of them taste like pineapple. I don’t Google squirrel on jet skis, but I Google the poem about the river that eats a boy who was supposed to be in class but wasn’t in class because the river ate him. That river is really fucking mean. I Google meanest river in the world and discover that Gustave is the world’s meanest crocodile. Gustave is greatly feared by people living by the shores of the Ruzizi River in Burundi. I don’t Google Burundi but instead think Bundt cake. I Google emotion. There are dirty dishes in the sink. I miss your neck between my teeth. There are so many girls I will never have to kiss.

–Gregory Sherl, diode

2

The very first Vacuum Tube Diode is called the Fleming Valve invented by John Fleming and is first used for radio communications. Let me explain what a diode does first. A diode basically controls the flow of current in one direction and block the current in another direction, basically like a switch. When the battery’s polarity allows electrons to flow through the diode, it is said to be forward-biased, and of course, if it’s the other way around, it’s reverse-biased. From the vacuum tube diode Fleming invented, came semiconductor diodes which are mostly made up of silicon. The very first semiconductor diode is called the “Cat’s Whisker” invented by Bose and other dudes. 

Sorry I didn’t post the last couple of days, I’ve been really busy.  But today’s post is about bridge rectifiers.

The term “rectifier” means a device which takes an alternating current and “rectifies” it into direct current.  The simplest way to do this is by simply using a diode.  Since diodes only allow current to flow one way, the negative part of the input will not be fed through the diode, so you will only get voltages above 0v.  However, this method chops out half of the available current, and when you’re trying to rectify AC power to use as a power supply, you want all of the available power from your transformer.

A bridge rectifier solves this problem.  It’s basically the same concept as behind the H-bridge, but instead of using a control signal to switch transistors on and off, the diodes automatically turn on and off based on the direction of current.  There are two diodes connected to each end of the AC supply (usually the secondary coil of a transformer, as in this schematic) and those diodes point opposite directions.  The diode that points “away” from that terminal is connected to negative, and the diode that points “toward” the terminal is connected to positive.  Since the two terminals of the AC supply will always be opposite voltages of each other, there will always be one terminal connected to positive and one connected to negative.  This is shown in the schematic by red and blue.  When the input signal is positive, the red diodes become conductive.  However, when the input signal is negative, the blue diodes become conductive.

If the negative output of the bridge rectifier is defined as 0v, the positive output will never put out a negative voltage.  This feeds current into RL (a resistive load) in only one direction.  However, since the input signal is a sine wave, the voltage on the output is not always the same, it goes up and down between VMAX and 0v.  This is known as ripple, and is usually bad.  To get rid of this ripple and smooth out the output voltage to a more stable value, a very large capacitor is usually connected across the positive and negative outputs of the rectifier.  This capacitor is charged up during the peaks, and discharges during the valleys, keeping the output voltage in the same as long as you don’t draw too much current.

This is similar to the function of your car’s suspension when you’re driving on an uneven surface.  When you hit a bump, the wheel pushes up and lowers again when you pass the bump.  If you hit a pothole, the wheel drops into the hole and raises back up when the hole ends.  If your car had no suspension, you would have a VERY rough ride on even seemingly even surfaces.  The “missing” current is filled in by the capacitor just like the “missing” road surface is filled in by the give in the wheel’s suspension.  This is also frequently done to eliminate ripple from DC power supplies that are affected by inconsistent current draw from their circuits.

To one person only

Bob Hicok

The woods I got lost in as a child
are gone. Trees meander now

miles apart. I walk from one
to another, connecting them with a touch

into pairs and quartets, squadrons
flying below the radar

of improvement. The woods
of my neocortex go on

for years but the woods
I learned to say woods in

are gone. The woods I lost
my virginity in were chopped down

for flower boxes and bungalows, kindling
reminds me of what I see

in the mirror. The mountain
is hairy with trees but bereft

of you, we never walked there, my chance
to walk there with you

is gone. Woods in fog with you, rain with you,
in snow glistening, snow listens

to footfalls, breaths, it’s the spaces
between crystals: almost forgiveness, ears.

diode

i admire you because you are ideal, hindi ko naman alam na nakareverse bias ka.


ang isang diode, pwedeng naka-forward o kaya reverse-bias. may mga diode na tinatawag nating ideal. parang tao… may mga ideal na tao. hindi man perfect, very near naman sa perfection sa standards natin. ang ideal diode, pagnakaforward bias ay operating agad. kapag nakareverse.. kahit gaanong kalaking boltahe yan… di yan mag-ooperate. parang tao… pagnakaforward bias sayo, edi swak.. masaya ang buhay mo. pag nakareverse naman, kahit anong gawin mo… hindi yan matitinag…