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555 timer astable monostable

555 Timer PRO, and the extended version 555 Timer PRO EX, are the best 555 timer references available.

With almost a half million downloads so far, users have found our timer software to be superior to any other printed or digital resources.

Each provides an array of design wizards, circuit blocks and information panels that facilitate the use of the 555 timer in projects. Component value calculations for the 555 take into account the supply voltage, timer fabrication (CMOS or Bipolar), and, where appropriate, load currents.

Features include:

  • 555 timer synopsis - includes pin functions, fabrication differences, component selection
  • 22 timer design wizards - 14 for the astable mode, 8 for the monostable mode
  • input circuits - for gating an astable or triggering a monostable. Input categories are switch, touch plate, continuity, liquid level, AC detect, light, sound, and temperature.
  • counter wizards - facilitate divide by/count to strategies using common binary and decade counters
  • output circuits - that can be activated by the 555 timer. Includes switching loads, driving motors, driving LEDs, lamps, numeric and bar graph displays, and audio, ultrasound and RF outputs
  • general - voltage reference design, "best pair" resistor substitution, logic families reference, IC pin outs for all ICs used in 555 Timer PRO EX
  • PDF file output - create complete projects by writing all project circuit blocks to one convenient PDF file

555 Timer PRO and 555 Timer PRO EX (extended) are combined in the same demo download. Simply toggle between modes to view the features of each. Most resistor values are masked in the demo; some circuits are electronically blurred; some menu items are disabled.

Below are a few examples taken from the 7 major categories and 46 subcategories of 555 Timer PRO.

Click on any image to enlarge...

Main application window

555 Timer PRO main screen

One of the 555 timer overview screens. Topics include CMOS vs bipolar, bypassing, component selection, timer accuracy and control voltage

555 Timer PRO overview screen

Astable mode calculator, with standard, wide-range and square-wave categories, as well as 10 additional groups of related circuits

555 Timer PRO astable screen

Circuit application example, taken from Input Circuits...Continuity section.

555 Timer PRO example screen

555 Timer PRO and 555 Timer PRO EX (extended) are combined in the same demo download. Simply toggle between modes to view the features of each. Most resistor values are masked in the demo; some circuits are electronically blurred; some menu items are disabled.

Comparison of 555 Timer PRO and 555 Timer PRO EX:


555 timer design software PRO PRO EX
Timer design wizards
Astable mode, duty cycle > 50% 4 4
Astable mode, 0%-duty cycle-100% 9 9
Astable mode, square wave 3 3
Monostable mode (one-shot) 8 8
Adjusted for supply voltage, fabrication, load currents YES YES
Support circuitry
Input circuit library 47 47
567 tone decoder wizard YES YES
Photo diode amplifier wizard   YES
Digital counter/divider wizards YES YES
Output circuit library 41 41
Triac snubber wizard YES YES
LM386 audio amplifier wizard YES YES
Voltage reference wizards YES YES
Best-pair resistor wizard YES YES
Logic family overview YES YES
Active filter design wizard, LP, HP, BP, BS to order 6   YES
Operational amplifier design wizards   YES
Transistor amplifier design wizard   YES
Price (USD) $16 $21

555 Timer PRO and 555 Timer PRO EX v3.1 download [May 13, 2014]

555 Timer PRO and 555 Timer PRO EX are combined in one application. Purchase of a licence and registration of the product enables the full 555 Timer PRO or PRO EX mode.

A single-user license authorizes the licensee (only) to operate the software on two computers, such as a work computer and a home computer.

This application or its setup file, or any portion thereof, may not be redistributed by any means whatsoever, except with the expressed permission of Schematica Software.

Most resistor values are masked in the demo; some circuits are electronically blurred; some menu items are disabled.


Compatible with Windows 7, Vista, XP, 2K


555 Timer PRO

EXE setup file:

TimerPRO2_Setup.exe 5.62 MB 555 Timer PRO

Archived setup file:

TimerPRO2_Setup.zip 5.59 MB 555 Timer PRO


Upgrading from version 1? The upgrade is free. Please install Version 2 to a new folder.


Please report any downloading problems to support@schematica.com.