{"id":78,"date":"2014-05-13T19:12:51","date_gmt":"2014-05-13T19:12:51","guid":{"rendered":"http:\/\/daqdesign.wordpress.com\/?p=78"},"modified":"2026-10-25T11:41:49","modified_gmt":"2026-10-25T11:41:49","slug":"the-ubiquitous-ne555-timer-integrated-circuit","status":"publish","type":"post","link":"https:\/\/daq-design.co.uk\/blog\/?p=78","title":{"rendered":"The (ubiquitous) NE555 timer integrated circuit"},"content":{"rendered":"\n

The NE555<\/a> is an inexpensive timer IC that can be configured to run in monostable i.e a single stable state or in timer mode with the addition of a few passive components. It is very easy to use and configurable over numerous decades from a few miliseonds to several hours – although brief and long delays can be unreliable due to tolerances in the external passive components .<\/p>\n\n\n\n

NE555 in the astable configuration<\/strong><\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

<\/p>\n\n\n\n

 <\/p>\n\n\n\n

The circuit shown above shows the 555 configured as an astable multivibrator by selecting the values of R1, R2 and C1 the frequency of the oscillator can be configured.<\/p>\n\n\n\n

The Clock out (pin3) frequency can be represented as follows:<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

<\/p>\n\n\n\n

Here’s a python script you can run to work out the component values. An approximate 1Hz oscillator can be obtained with R1=10K\u03a9, R2=10K\u03a9 and C1=47\u03bcF<\/p>\n\n\n\n

Python 2.6 NE555 timer calculator. <\/strong><\/p>\n\n\n\n

# 555 timer calculator\n# Useful sites on the 555.\n# http:\/\/freespace.virgin.net\/matt.waite\/resource\/handy\/pinouts\/555\/\n# http:\/\/www.ohmslawcalculator.com\/555_astable.php\n#\n# (C) G.P.Walker 25th March 2014.\n# first calculation is for a Monostable\n# second calculation od for an Astable\n# next version move to give a choice and add further technical details - duty cycle etc\n# Also look to do a parameteric sweep on the values so you can see how Fc is changed\n# by altering the values as a paramater :)\n#\n# Notes:\n# Increasing C will increase the cycle time (and hence, reduce the frequency).\n# Increasing R1 will increase Time High, but will leave Time Low unaffected.\n# Increasing R2 will increase Time High, increase time low and decrease the duty cycle (down to a minimum of 50%)\n# This version supports the changes made in python3 to  the input function\n# This version 30th October 2023\n\nfrom os import *\nsystem('clear')\nprint(\"NE555 timer circuit calculator\")\nprint(\"(C) G.P.Walker March 2014 greg@gregwalker.me.uk\")\nprint(\"\")\nprint(\"1) Monostable:\")\nprint(\"2) Astable:\")\nprint(\"\")\nanswer=(int(input(\"Enter a value for the type of circuit you want: \")))\n\nif answer==1:\n print(\"\")\n r=float(input(\"Enter the value of the resitor connected to Vcc and pin 6: \"))\n c=float(input(\"Enter the value of the capacitor connected to pin6 and GND: \"))\n t=(1.1*(r*c))\n print (\"This circuit will produce a pulse of duration: %0.3f\" %t + \" seconds\")\n\nelif answer==2:\n\n print(\"\")\n r1=float(input(\"Enter the value of r1 connected to Vcc and pin 7: \"))\n r2=float(input(\"Enter the value of r2 connected to pin 7 and pin 6: \"))\n c=float(input(\"Enter the value of c connected to pin 6 and GND: \"))\n f=1.45\/((r1+(2*r2))*c)\n print (\"\\nThis circuit will produce an square wave of: %0.3f\" %f +\" Hertz\\n\")\n print(\"Node connections for the astable are as follows:\")\n print(\"Pin 1 to GND:\")\n print(\"Pin 2 to Pin 6\")\n print(\"Oscillator's output is on Pin 3\")\n print(\"Pins 4 and 8 to Vcc:\")\n print(\"Pin 5 to Gnd via a 10nF cap - or leave it floating\\n\")\n\n\n\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
The NE555 is an inexpensive timer IC that can be configured to run in monostable i.e a single stable state or in timer mode with the addition of a few passive components. It is very easy to use and configurable over … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[9,13,18,19],"class_list":["post-78","post","type-post","status-publish","format-standard","hentry","category-ics","tag-astable-multivibrator","tag-gnu-general-public-license","tag-ne555-timer","tag-ne555-timer-calculator"],"_links":{"self":[{"href":"https:\/\/daq-design.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/posts\/78","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/daq-design.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/daq-design.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/daq-design.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/daq-design.co.uk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=78"}],"version-history":[{"count":7,"href":"https:\/\/daq-design.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/posts\/78\/revisions"}],"predecessor-version":[{"id":616,"href":"https:\/\/daq-design.co.uk\/blog\/index.php?rest_route=\/wp\/v2\/posts\/78\/revisions\/616"}],"wp:attachment":[{"href":"https:\/\/daq-design.co.uk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=78"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/daq-design.co.uk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=78"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/daq-design.co.uk\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=78"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}