‰  NOW 30 WPM  ‰  TEXT IS FROM NOVEMBER 2012 QST  PAGE 65‰

12 V DC TO ABOUT 120 V THE EXACT VOLTAGE DEPENDS ON THE DESIGN OF THE UNIT.
THIS VOLTAGE IS OFTEN CALLED THE LINK BUS, BECAUSE IT LINKS THE BOOST STAGE
WITH THE SECOND STAGE, WHICH INVERTS THE HIGHER VOLTAGE DC TO AC.  THE
INVERTER CONSISTS OF FOUR TRANSISTORS, WHICH SWITCH THE HOT AND NEUTRAL
OUTPUT LINES BETWEEN THE POSITIVE OR NEGATIVE SIDES OF THE LINK BUS AT THE
DESIRED OUTPUT FREQUENCY.  THE SWITCHING OF THE HOT AND NEUTRAL TRANSISTORS
IS STAGGERED TO PRODUCE A BETTER OUTPUT VOLTAGE WAVEFORM.  FIGURE 3 SHOWS
THE APPROXIMATE TIMING OF THE SWITCHING.  AT THE START OF THE GRAPH, BOTH
THE HOT AND NEUTRAL LEADS ARE CONNECTED TO THE BUS AND THERE IS NO OUTPUT
VOLTAGE.  ABOUT 4 MS LATER THE HOT LEAD IS SWITCHED TO THE BUS AND 120 V
APPEARS BETWEEN THE HOT AND THE NEUTRAL LINE.  IN ANOTHER 4 MS THE NEUTRAL
LEAD IS SWITCHED TO THE BUS AND AGAIN NO VOLTAGE APPEARS BETWEEN THE HOT
AND NEUTRAL LEADS BECAUSE BOTH ARE AT 120 V.  AFTER ANOTHER 4 MS, THE HOT
LEAD IS SWITCHED TO THE BUS AND AGAIN AND 120 V APPEARS BETWEEN THE HOT AND
NEUTRAL LEADS, BUT NOW THE NEUTRAL IS POSITIVE AND THE HOT IS NEGATIVE.  IN
4 MS THE NEUTRAL IS SWITCHED TO THE BUS AND WE ARE BACK TO THE STARTING
‰  END OF 30 WPM TEXT  ‰  QST DE W1AW  ƒ