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555 timer astable monostable

555 Timer PRO EX is the best 555 timer reference 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.

555 Timer PRO EX includes all the features of 555 Timer PRO plus wizards for active filter design, photodiode amplifiers, op amp amplifiers and transistor amplifiers.

As with 555 Timer PRO, 555 Timer PRO EX 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 circuitry - 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 circuitry - 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
  • active filter wizards - create order 2, 4 or 6 active low pass, high pass, band pass or band stop filters using the Butterworth, Chebyshev or Elliptic approximations, and the reliable Multiple-Feedback (MFB) implementation
  • transistor design wizards - design a very stable emitter-bypassed NPN transistor amplifier with gain from 40 to 400
  • operational amplifier design wizards - design inverting and non-inverting amplifiers with DC or AC coupling and single or dual supplies.
  • 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.

Click on any image to enlarge...

Main screen of 555 timer project design software

555 Timer PRO EX main screen

Timer design wizard - 16 astable and 8 monostable configurations

555 Timer PRO EX astable screen

Counter/Division wizard - create long interval timers or divide down higher frequency pulse trains

555 Timer PRO EX counter

Photodiode wizard - amplify light signals in either photoconductive or photovoltaic modes

555 Timer PRO EX photodiode wizard

Active filter wizard - add a low pass, high pass, band pass or band stop filter to your project (up to order 6)

555 Timer PRO EX active filter wizard

Transistor AC amplifier wizard - create stable amplifiers with gains from 1 to 400

555 Timer PRO EX transistor wizard

Best resistor pair wizard - enter any value and find a series and parallel combination

555 Timer PRO EX resistor wizard

Op amp amplifier - add single or dual supply amplifiers to your project

555 Timer PRO EX resistor wizard

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 project 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
Photodiode 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 (formerly 555 Etcetera) 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. Note that 555 Timer PRO EX was formerly named 555 Etcetera.


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