‰  NOW 35 WPM  ‰  TEXT IS FROM MAY 2015  QST  PAGE 32 ‰

A VOLTAGE OR POWER MONITOR THIS VERSATILE MICROCONTROLLER BASED CIRCUIT
PROVIDES CRITICAL INFORMATION AT A GLANCE.  MERT NELLIS, W0UFO  I
PREVIOUSLY WROTE A BATTERY MONITOR ARTICLE FOR QST THAT USED AN LM339
COMPARATOR, BUT THIS ONE, BASED ON THE PICAXE 18M2 MICROCONTROLLER, IS
EASIER TO BUILD, TO CALIBRATE, AND CAN HAVE MANY MORE MONITOR LEVELS.  I
USE ONE ANALOG TO DIGITAL ADC INPUT AND 11 OUTPUTS.  THUS IT PROVIDES 20
LEVELS OF VOLTAGE MONITORING IN TWO DECADES, OR 11 LEVELS OF RF POWER
MONITORING.  FOR FEWER OUTPUTS, YOU CAN USE THE LOWER COST PICAXE 08M2,
WHICH CAN PROVIDE THREE MONITOR POINTS IN AN EIGHT PIN PACKAGE.  MY PICAXE
BASED CIRCUIT FIGURE 1 INDICATES EITHER VOLTAGE OR RF POWER BY LIGHTING
ELEVEN LEDS.  I PROGRAMMED MINE FOR 5 TO 14R5 V IN 1/2 V STEPS AND 1 TO 11
W IN 1R0 W STEPS.  I COMBINED BOTH VOLTAGE AND RF POWER MONITORS INTO ONE
UNIT, BUT YOUR PURPOSES MIGHT BE BETTER SERVED BY SEPARATE DEDICATED
MONITORS.  THE MICROCONTROLLER SYSTEM THE PICAXE SYSTEM USES BASIC FOR
PROGRAMMING.  YOU CAN DOWNLOAD THE EDITOR, SIMULATOR, AND PROGRAMMER
SOFTWARE FOR FREE FROM THE PICAXE WEBSITE.  THIS CIRCUIT AND EXAMPLE CODE
ARE JUST ONE POSSIBILITY.  YOU CAN EASILY CHANGE THE PROGRAM TO MONITOR ANY
FUNCTION THAT YOU WANT.  FOR PROGRAM DOWNLOADING AND EDITING, CONNECT A
SERIAL PROGRAMMING CABLE FROM THE COMPUTER TO THE 1/8 INCH CIRCUIT JACK J1
‰  END OF 35 WPM TEXT  ‰  QST DE W1AW  ƒ