https://community.element14.com/challenges-projects/element14-presents/thelearningcircuit/w/documents/4833/555-timers---how-bistable-mode-works----the-learning-circuit-70en-USTelligent Community 12https://community.element14.com/challenges-projects/element14-presents/thelearningcircuit/w/documents/4833/555-timers---how-bistable-mode-works----the-learning-circuit-70Wed, 08 Jan 2020 08:24:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:a431c9e3-b95f-4268-a252-80237c40bdd6Matthttps://community.element14.com/challenges-projects/element14-presents/thelearningcircuit/w/documents/4833/555-timers---how-bistable-mode-works----the-learning-circuit-70#commentsCurrent Revision posted to Documents by Matt on 1/8/2020 8:24:00 AM<br /> <div style="background:#ffffff;border:1px solid #dadada;margin:0;padding:14px 16px 16px 18px;vertical-align:top;"> <div style="display:inline-block;float:left;padding:0px 25px 8px 0px;"><a href="/challengesprojects/element14-presents/" data-e14adj="t"><img alt="image" src="/e14/assets/legacy/2018/e14PresentsJune818.png" width="180px" /></a></div> <div style="display:inline-block;vertical-align:top;width:70%;"><span style="color:#000000;font-family:Roboto, RobotoDraft, Helvetica, Arial, sans-serif;font-size:14pt;font-weight:bold;">555 Timers - How Bistable Mode Works</span> <p style="margin:0;"><span style="font-size:14pt;"><a class="jivecontainerTT-hover-container jive-link-community-small" href="/challengesprojects/element14-presents/thelearningcircuit/" data-e14adj="t">The Learning Circuit</a> <strong>|</strong> <a class="jivecontainerTT-hover-container jive-link-community-small" href="/challengesprojects/element14-presents/" data-e14adj="t">element14 presents</a> <strong>|</strong>&nbsp; <a class="jivecontainerTT-hover-container jive-link-community-small" href="/challengesprojects/element14-presents/project-videos/" data-e14adj="t">Project Videos</a></span></p> </div> </div> <p style="margin:0;padding:0px;">&nbsp;</p> <p style="margin:0;"></p> <p><span><a href="https://www.youtube.com/watch?v=G0Qkn0f35cw">www.youtube.com/watch</a></span></p> <p style="margin:0;"></p> <p style="margin:0;padding:0px;">&nbsp;</p> <p style="background-color:#e9f6fc;border:1px solid #b8d7e5;margin:0;max-width:744px;padding:8px;"><span style="color:#000000;font-family:&#39;Open Sans&#39;, Arial, sans-serif;text-align:justify;">Karen has been digging into 555 timers for a bit now. In a previous video, she did an overview of the 3 different modes in which a 555 timer can be used. In this video, Karen goes into further detail about one of those modes: Bistable. In bistable mode, signals at two inputs are used to manually set the output of the 555 timer high or low. For example, one button could trigger the output to turn a light on, while a second button could reset the output to turn the light off. This video goes over what is happening in the 555 timer internally to make this type of circuit work. Karen also presents a practical example on a breadboard to show using a 555 timer in bistable mode. </span></p> <p style="margin:0;padding:0px;">&nbsp;</p> <p style="margin:0;padding:0px;">&nbsp;</p> <h2><span style="color:#3334ca;">Bill of Material:</span></h2> <p style="margin:0;padding:0px;">&nbsp;</p> <p style="margin:0;padding:0px;">&nbsp;</p> <table class="jiveBorder" style="border:1px solid #C6C6C6;" border="1"> <thead> <tr> <th style="background-color:#f2f2f2;border:1px solid #C6C6C6;color:#505050;padding:6px;text-align:left;">Product Name</th> <th style="background-color:#f2f2f2;border:1px solid #C6C6C6;color:#505050;padding:6px;text-align:left;">Manufacturer</th> <th style="background-color:#f2f2f2;border:1px solid #C6C6C6;color:#505050;padding:6px;text-align:left;">Quantity</th> <th style="background-color:#f2f2f2;border:1px solid #C6C6C6;color:#505050;padding:6px;text-align:left;"><span><span id="addProduct-m74ute0G-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2527467~1,2454497~1,2944281~1,2213344~1,1879252~1,1099893~2,1208853~1,1960971~1,2543104~1&amp;nsku=99W1760~1,58K8943~1,91K7219~1,54T9598~1,84R1814~1,78R4867~2,97K4136~1,52F3557~1,67P3652~1&amp;COM=noscript" target="_blank" data-e14adj="t"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2527467~1,2454497~1,2944281~1,2213344~1,1879252~1,1099893~2,1208853~1,1960971~1,2543104~1&amp;nsku=99W1760~1,58K8943~1,91K7219~1,54T9598~1,84R1814~1,78R4867~2,97K4136~1,52F3557~1,67P3652~1&amp;COM=noscript" target="_blank" data-e14adj="t">Buy Kit</a></span><span id="addProduct-m74ute0G-unlinked" class="e14-init-hidden">Buy Kit</span></span></th> </tr> </thead> <tbody> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">Breadboard, MCM 60 rows, ABS, 8.5mm, 165mm x 56mm</td> <td style="border:1px solid #C6C6C6;padding:6px;">Multicomp</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-1idZDr9l-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2527467~1&amp;nsku=99W1760~1&amp;COM=noscript" target="_blank" data-e14adj="t"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2527467~1&amp;nsku=99W1760~1&amp;COM=noscript" target="_blank" data-e14adj="t">Buy Now</a></span><span id="addProduct-1idZDr9l-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">LM555CN - Timer, Oscillator &amp; Pulse Generator IC, TTL Compatible, Astable, Monostable, 4.5 V to 16 V, DIP-8</td> <td style="border:1px solid #C6C6C6;padding:6px;">On Semiconductor</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-dcqQY9Mw-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2454497~1&amp;nsku=58K8943~1&amp;COM=noscript" target="_blank" data-e14adj="t"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2454497~1&amp;nsku=58K8943~1&amp;COM=noscript" target="_blank" data-e14adj="t">Buy Now</a></span><span id="addProduct-dcqQY9Mw-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">Ceramic Disc Capacitor, 0.01 &micro;F, 100 V, &plusmn; 20%, 5 mm</td> <td style="border:1px solid #C6C6C6;padding:6px;">Vishay</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-BrrF2hmU-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2944281~1&amp;nsku=91K7219~1&amp;COM=noscript" target="_blank" data-e14adj="t"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2944281~1&amp;nsku=91K7219~1&amp;COM=noscript" target="_blank" data-e14adj="t">Buy Now</a></span><span id="addProduct-BrrF2hmU-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">140 Pc. Jumper Wire Kit, 22 AWG, Solid, Assorted Lengths and Colors</td> <td style="border:1px solid #C6C6C6;padding:6px;">Twin Industries</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-i3VoTmx6-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2213344~1&amp;nsku=54T9598~1&amp;COM=noscript" target="_blank" data-e14adj="t"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2213344~1&amp;nsku=54T9598~1&amp;COM=noscript" target="_blank" data-e14adj="t">Buy Now</a></span><span id="addProduct-i3VoTmx6-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">Through Hole Resistor, 220 ohm, 400 mW, &plusmn; 1%</td> <td style="border:1px solid #C6C6C6;padding:6px;">Vishay</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-bs9xtZPW-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=1879252~1&amp;nsku=84R1814~1&amp;COM=noscript" target="_blank" data-e14adj="t"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=1879252~1&amp;nsku=84R1814~1&amp;COM=noscript" target="_blank" data-e14adj="t">Buy Now</a></span><span id="addProduct-bs9xtZPW-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">Through Hole Resistor, 1 kohm, 500 mW, &plusmn; 1%</td> <td style="border:1px solid #C6C6C6;padding:6px;">TT ELECTRONICS / WELWYN</td> <td style="border:1px solid #C6C6C6;padding:6px;">2</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-PQtlguuR-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=1099893~2&amp;nsku=78R4867~2&amp;COM=noscript" target="_blank" data-e14adj="t"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=1099893~2&amp;nsku=78R4867~2&amp;COM=noscript" target="_blank" data-e14adj="t">Buy Now</a></span><span id="addProduct-PQtlguuR-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">Red LED, Through Hole, 5mm, 20 mA, 2.1 V</td> <td style="border:1px solid #C6C6C6;padding:6px;">LED TECHNOLOGY</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-XGFjIcRv-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=1208853~1&amp;nsku=97K4136~1&amp;COM=noscript" target="_blank" data-e14adj="t"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=1208853~1&amp;nsku=97K4136~1&amp;COM=noscript" target="_blank" data-e14adj="t">Buy Now</a></span><span id="addProduct-XGFjIcRv-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">Tactile Switch, 12mm, Yellow, Top Actuated, Through Hole, Round Button, 24 VDC, 50mA</td> <td style="border:1px solid #C6C6C6;padding:6px;">Omron</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-6DoKtqG0-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=1960971~1&amp;nsku=52F3557~1&amp;COM=noscript" target="_blank" data-e14adj="t"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=1960971~1&amp;nsku=52F3557~1&amp;COM=noscript" target="_blank" data-e14adj="t">Buy Now</a></span><span id="addProduct-6DoKtqG0-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">Tactile Switch, 12mm, Red, 12 VDC, 50mA</td> <td style="border:1px solid #C6C6C6;padding:6px;">Multicomp</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-NDj2MU2O-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2543104~1&amp;nsku=67P3652~1&amp;COM=noscript" target="_blank" data-e14adj="t"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2543104~1&amp;nsku=67P3652~1&amp;COM=noscript" target="_blank" data-e14adj="t">Buy Now</a></span><span id="addProduct-NDj2MU2O-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> </tbody> </table> <p style="margin:0;padding:0px;">&nbsp;</p> <h2><span style="color:#3334ca;">Additional Parts:</span></h2> <p style="margin:0;padding:0px;">&nbsp;</p> <table class="jiveBorder" style="border:1px solid #000000;width:100%;" border="1"> <thead> <tr> <th style="background-color:#6690bc;border:1px solid #000000;color:#ffffff;padding:2px;text-align:left;" valign="middle"><strong>Product Name</strong></th> </tr> </thead> <tbody> <tr> <td style="border:1px solid #000000;padding:2px;">Desktop Power Supply</td> </tr> </tbody> </table> <p style="margin:0;padding:0px;">&nbsp;</p> <p style="margin:0;"><br /><br /></p><div style="clear:both;"></div> <div style="font-size: 90%;">Tags: e14presents_karencorbeill, bistable, e14presents_makerkaren, the learning circuit 70: 555 timers - how bistable mode, 555 timer, 555 timers, 555</div> https://community.element14.com/challenges-projects/element14-presents/thelearningcircuit/w/documents/4833/555-timers---how-bistable-mode-works----the-learning-circuit-70/revision/2Thu, 14 Jul 2022 14:05:24 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:a431c9e3-b95f-4268-a252-80237c40bdd6kellyhensenhttps://community.element14.com/challenges-projects/element14-presents/thelearningcircuit/w/documents/4833/555-timers---how-bistable-mode-works----the-learning-circuit-70#commentsRevision 2 posted to Documents by kellyhensen on 7/14/2022 2:05:24 PM<br /> <div style="background:#ffffff;border:1px solid #dadada;margin:0;padding:14px 16px 16px 18px;vertical-align:top;"> <div style="display:inline-block;float:left;padding:0px 25px 8px 0px;"><a href="/challengesprojects/element14-presents/"><img alt="image" src="/e14/assets/legacy/2018/e14PresentsJune818.png" width="180px" /></a></div> <div style="display:inline-block;vertical-align:top;width:70%;"><span style="color:#000000;font-family:Roboto, RobotoDraft, Helvetica, Arial, sans-serif;font-size:14pt;font-weight:bold;">555 Timers - How Bistable Mode Works</span> <p style="margin:0;"><span style="font-size:14pt;"><a class="jivecontainerTT-hover-container jive-link-community-small" href="/challengesprojects/element14-presents/thelearningcircuit/">The Learning Circuit</a> <strong>|</strong> <a class="jivecontainerTT-hover-container jive-link-community-small" href="/challengesprojects/element14-presents/">element14 presents</a> <strong>|</strong>&nbsp; <a class="jivecontainerTT-hover-container jive-link-community-small" href="/challengesprojects/element14-presents/project-videos/">Project Videos</a></span></p> </div> </div> <p style="margin:0;padding:0px;">&nbsp;</p> <p style="margin:0;"></p> <p><span><a href="https://www.youtube.com/watch?v=G0Qkn0f35cw">www.youtube.com/watch</a></span></p> <p style="margin:0;"></p> <p style="margin:0;padding:0px;">&nbsp;</p> <p style="background-color:#e9f6fc;border:1px solid #b8d7e5;margin:0;max-width:744px;padding:8px;"><span style="color:#000000;font-family:&#39;Open Sans&#39;, Arial, sans-serif;text-align:justify;">Karen has been digging into 555 timers for a bit now. In a previous video, she did an overview of the 3 different modes in which a 555 timer can be used. In this video, Karen goes into further detail about one of those modes: Bistable. In bistable mode, signals at two inputs are used to manually set the output of the 555 timer high or low. For example, one button could trigger the output to turn a light on, while a second button could reset the output to turn the light off. This video goes over what is happening in the 555 timer internally to make this type of circuit work. Karen also presents a practical example on a breadboard to show using a 555 timer in bistable mode. </span></p> <p style="margin:0;padding:0px;">&nbsp;</p> <p style="margin:0;padding:0px;">&nbsp;</p> <h2><span style="color:#3334ca;">Bill of Material:</span></h2> <p style="margin:0;padding:0px;">&nbsp;</p> <p style="margin:0;padding:0px;">&nbsp;</p> <table class="jiveBorder" style="border:1px solid #C6C6C6;" border="1"> <thead> <tr> <th style="background-color:#f2f2f2;border:1px solid #C6C6C6;color:#505050;padding:6px;text-align:left;">Product Name</th> <th style="background-color:#f2f2f2;border:1px solid #C6C6C6;color:#505050;padding:6px;text-align:left;">Manufacturer</th> <th style="background-color:#f2f2f2;border:1px solid #C6C6C6;color:#505050;padding:6px;text-align:left;">Quantity</th> <th style="background-color:#f2f2f2;border:1px solid #C6C6C6;color:#505050;padding:6px;text-align:left;"><span><span id="addProduct-m74ute0G-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2527467~1,2454497~1,2944281~1,2213344~1,1879252~1,1099893~2,1208853~1,1960971~1,2543104~1&amp;nsku=99W1760~1,58K8943~1,91K7219~1,54T9598~1,84R1814~1,78R4867~2,97K4136~1,52F3557~1,67P3652~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2527467~1,2454497~1,2944281~1,2213344~1,1879252~1,1099893~2,1208853~1,1960971~1,2543104~1&amp;nsku=99W1760~1,58K8943~1,91K7219~1,54T9598~1,84R1814~1,78R4867~2,97K4136~1,52F3557~1,67P3652~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank">Buy Kit</a></span><span id="addProduct-m74ute0G-unlinked" class="e14-init-hidden">Buy Kit</span></span></th> </tr> </thead> <tbody> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">Breadboard, MCM 60 rows, ABS, 8.5mm, 165mm x 56mm</td> <td style="border:1px solid #C6C6C6;padding:6px;">Multicomp</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-1idZDr9l-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2527467~1&amp;nsku=99W1760~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2527467~1&amp;nsku=99W1760~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank">Buy Now</a></span><span id="addProduct-1idZDr9l-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">LM555CN - Timer, Oscillator &amp; Pulse Generator IC, TTL Compatible, Astable, Monostable, 4.5 V to 16 V, DIP-8</td> <td style="border:1px solid #C6C6C6;padding:6px;">On Semiconductor</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-dcqQY9Mw-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2454497~1&amp;nsku=58K8943~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2454497~1&amp;nsku=58K8943~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank">Buy Now</a></span><span id="addProduct-dcqQY9Mw-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">Ceramic Disc Capacitor, 0.01 &micro;F, 100 V, &plusmn; 20%, 5 mm</td> <td style="border:1px solid #C6C6C6;padding:6px;">Vishay</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-BrrF2hmU-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2944281~1&amp;nsku=91K7219~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2944281~1&amp;nsku=91K7219~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank">Buy Now</a></span><span id="addProduct-BrrF2hmU-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">140 Pc. Jumper Wire Kit, 22 AWG, Solid, Assorted Lengths and Colors</td> <td style="border:1px solid #C6C6C6;padding:6px;">Twin Industries</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-i3VoTmx6-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2213344~1&amp;nsku=54T9598~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2213344~1&amp;nsku=54T9598~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank">Buy Now</a></span><span id="addProduct-i3VoTmx6-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">Through Hole Resistor, 220 ohm, 400 mW, &plusmn; 1%</td> <td style="border:1px solid #C6C6C6;padding:6px;">Vishay</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-bs9xtZPW-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=1879252~1&amp;nsku=84R1814~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=1879252~1&amp;nsku=84R1814~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank">Buy Now</a></span><span id="addProduct-bs9xtZPW-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">Through Hole Resistor, 1 kohm, 500 mW, &plusmn; 1%</td> <td style="border:1px solid #C6C6C6;padding:6px;">TT ELECTRONICS / WELWYN</td> <td style="border:1px solid #C6C6C6;padding:6px;">2</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-PQtlguuR-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=1099893~2&amp;nsku=78R4867~2&amp;COM=noscript" rel="noopener noreferrer" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=1099893~2&amp;nsku=78R4867~2&amp;COM=noscript" rel="noopener noreferrer" target="_blank">Buy Now</a></span><span id="addProduct-PQtlguuR-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">Red LED, Through Hole, 5mm, 20 mA, 2.1 V</td> <td style="border:1px solid #C6C6C6;padding:6px;">LED TECHNOLOGY</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-XGFjIcRv-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=1208853~1&amp;nsku=97K4136~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=1208853~1&amp;nsku=97K4136~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank">Buy Now</a></span><span id="addProduct-XGFjIcRv-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">Tactile Switch, 12mm, Yellow, Top Actuated, Through Hole, Round Button, 24 VDC, 50mA</td> <td style="border:1px solid #C6C6C6;padding:6px;">Omron</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-6DoKtqG0-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=1960971~1&amp;nsku=52F3557~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=1960971~1&amp;nsku=52F3557~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank">Buy Now</a></span><span id="addProduct-6DoKtqG0-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> <tr> <td style="border:1px solid #C6C6C6;padding:6px;">Tactile Switch, 12mm, Red, 12 VDC, 50mA</td> <td style="border:1px solid #C6C6C6;padding:6px;">Multicomp</td> <td style="border:1px solid #C6C6C6;padding:6px;">1</td> <td style="border:1px solid #C6C6C6;padding:6px;"><span><span id="addProduct-NDj2MU2O-linked" class="e14-init-shown e14-product-link-buynow" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2543104~1&amp;nsku=67P3652~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2543104~1&amp;nsku=67P3652~1&amp;COM=noscript" rel="noopener noreferrer" target="_blank">Buy Now</a></span><span id="addProduct-NDj2MU2O-unlinked" class="e14-init-hidden">Buy Now</span></span></td> </tr> </tbody> </table> <p style="margin:0;padding:0px;">&nbsp;</p> <h2><span style="color:#3334ca;">Additional Parts:</span></h2> <p style="margin:0;padding:0px;">&nbsp;</p> <table class="jiveBorder" style="border:1px solid #000000;width:100%;" border="1"> <thead> <tr> <th style="background-color:#6690bc;border:1px solid #000000;color:#ffffff;padding:2px;text-align:left;" valign="middle"><strong>Product Name</strong></th> </tr> </thead> <tbody> <tr> <td style="border:1px solid #000000;padding:2px;">Desktop Power Supply</td> </tr> </tbody> </table> <p style="margin:0;padding:0px;">&nbsp;</p> <p style="margin:0;"><br /><br /></p><div style="clear:both;"></div> <div style="font-size: 90%;">Tags: e14presents_karencorbeill, bistable, e14presents_makerkaren, the learning circuit 70: 555 timers - how bistable mode, 555 timer, 555 timers, 555</div> https://community.element14.com/challenges-projects/element14-presents/thelearningcircuit/w/documents/4833/555-timers---how-bistable-mode-works----the-learning-circuit-70/revision/1Wed, 10 Jun 2020 13:57:05 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:a431c9e3-b95f-4268-a252-80237c40bdd6tariq.ahmadhttps://community.element14.com/challenges-projects/element14-presents/thelearningcircuit/w/documents/4833/555-timers---how-bistable-mode-works----the-learning-circuit-70#commentsRevision 1 posted to Documents by tariq.ahmad on 6/10/2020 1:57:05 PM<br /> <div style="background:#ffffff;padding:14px 16px 16px 18px;margin:0;vertical-align:top;border:1px solid #dadada;"><div style="float:left;display:inline-block;padding:0px 25px 8px 0px;"><a href="/challengesprojects/element14-presents/"><img alt="image" src="/e14/assets/legacy/2018/e14PresentsJune818.png" width="180px" /></a></div><div style="display:inline-block;vertical-align:top;width:70%;"><span style="color:#000000;font-weight:bold;font-size:14pt;font-family:Roboto, RobotoDraft, Helvetica, Arial, sans-serif;">555 Timers - How Bistable Mode Works</span><p style="margin:0;"><span style="font-size:14pt;"><a class="jivecontainerTT-hover-container jive-link-community-small" href="/challengesprojects/element14-presents/thelearningcircuit/">The Learning Circuit</a> <strong>|</strong> <a class="jivecontainerTT-hover-container jive-link-community-small" href="/challengesprojects/element14-presents/">element14 presents</a> <strong>|</strong>&nbsp; <a class="jivecontainerTT-hover-container jive-link-community-small" href="/challengesprojects/element14-presents/project-videos/">Project Videos</a></span></p></div></div><p style="margin:0;padding:0px;">&nbsp;</p><p style="margin:0;"></p><span><a href="https://www.youtube.com/watch?v=G0Qkn0f35cw">www.youtube.com/watch</a></span><p style="margin:0;"></p><p style="margin:0;padding:0px;">&nbsp;</p><p style="margin:0;border:1px solid #b8d7e5;background-color:#e9f6fc;padding:8px;max-width:744px;"><span style="color:#000000;font-family:&#39;Open Sans&#39;, Arial, sans-serif;text-align:justify;">Karen has been digging into 555 timers for a bit now. In a previous video, she did an overview of the 3 different modes in which a 555 timer can be used. In this video, Karen goes into further detail about one of those modes: Bistable. In bistable mode, signals at two inputs are used to manually set the output of the 555 timer high or low. For example, one button could trigger the output to turn a light on, while a second button could reset the output to turn the light off. This video goes over what is happening in the 555 timer internally to make this type of circuit work. Karen also presents a practical example on a breadboard to show using a 555 timer in bistable mode. </span></p><p style="margin:0;padding:0px;">&nbsp;</p><p style="margin:0;padding:0px;">&nbsp;</p><h2><span style="color:#3334ca;">Bill of Material:</span></h2><p style="margin:0;padding:0px;">&nbsp;</p><p style="margin:0;padding:0px;">&nbsp;</p><table border="1" class="jiveBorder mce-item-table" style="border:1px solid #C6C6C6;"><thead><tr><th style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;color:#505050;background-color:#f2f2f2;text-align:left;">Product Name</th><th style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;color:#505050;background-color:#f2f2f2;text-align:left;">Manufacturer</th><th style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;color:#505050;background-color:#f2f2f2;text-align:left;">Quantity</th><th style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;color:#505050;background-color:#f2f2f2;text-align:left;"><span><span class="e14-init-shown e14-product-link-buynow" id="addProduct-m74ute0G-linked" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2527467~1,2454497~1,2944281~1,2213344~1,1879252~1,1099893~2,1208853~1,1960971~1,2543104~1&amp;nsku=99W1760~1,58K8943~1,91K7219~1,54T9598~1,84R1814~1,78R4867~2,97K4136~1,52F3557~1,67P3652~1&amp;COM=noscript" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2527467~1,2454497~1,2944281~1,2213344~1,1879252~1,1099893~2,1208853~1,1960971~1,2543104~1&amp;nsku=99W1760~1,58K8943~1,91K7219~1,54T9598~1,84R1814~1,78R4867~2,97K4136~1,52F3557~1,67P3652~1&amp;COM=noscript" target="_blank">Buy Kit</a></span><span class="e14-init-hidden" id="addProduct-m74ute0G-unlinked">Buy Kit</span></span></th></tr></thead><tbody><tr><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">Breadboard, MCM 60 rows, ABS, 8.5mm, 165mm x 56mm</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">Multicomp</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">1</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;"><span><span class="e14-init-shown e14-product-link-buynow" id="addProduct-1idZDr9l-linked" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2527467~1&amp;nsku=99W1760~1&amp;COM=noscript" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2527467~1&amp;nsku=99W1760~1&amp;COM=noscript" target="_blank">Buy Now</a></span><span class="e14-init-hidden" id="addProduct-1idZDr9l-unlinked">Buy Now</span></span></td></tr><tr><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">LM555CN - Timer, Oscillator &amp; Pulse Generator IC, TTL Compatible, Astable, Monostable, 4.5 V to 16 V, DIP-8</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">On Semiconductor</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">1</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;"><span><span class="e14-init-shown e14-product-link-buynow" id="addProduct-dcqQY9Mw-linked" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2454497~1&amp;nsku=58K8943~1&amp;COM=noscript" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2454497~1&amp;nsku=58K8943~1&amp;COM=noscript" target="_blank">Buy Now</a></span><span class="e14-init-hidden" id="addProduct-dcqQY9Mw-unlinked">Buy Now</span></span></td></tr><tr><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">Ceramic Disc Capacitor, 0.01 µF, 100 V, ± 20%, 5 mm</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">Vishay</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">1</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;"><span><span class="e14-init-shown e14-product-link-buynow" id="addProduct-BrrF2hmU-linked" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2944281~1&amp;nsku=91K7219~1&amp;COM=noscript" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2944281~1&amp;nsku=91K7219~1&amp;COM=noscript" target="_blank">Buy Now</a></span><span class="e14-init-hidden" id="addProduct-BrrF2hmU-unlinked">Buy Now</span></span></td></tr><tr><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">140 Pc. Jumper Wire Kit, 22 AWG, Solid, Assorted Lengths and Colors</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">Twin Industries</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">1</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;"><span><span class="e14-init-shown e14-product-link-buynow" id="addProduct-i3VoTmx6-linked" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2213344~1&amp;nsku=54T9598~1&amp;COM=noscript" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2213344~1&amp;nsku=54T9598~1&amp;COM=noscript" target="_blank">Buy Now</a></span><span class="e14-init-hidden" id="addProduct-i3VoTmx6-unlinked">Buy Now</span></span></td></tr><tr><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">Through Hole Resistor, 220 ohm, 400 mW, ± 1%</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">Vishay</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">1</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;"><span><span class="e14-init-shown e14-product-link-buynow" id="addProduct-bs9xtZPW-linked" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=1879252~1&amp;nsku=84R1814~1&amp;COM=noscript" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=1879252~1&amp;nsku=84R1814~1&amp;COM=noscript" target="_blank">Buy Now</a></span><span class="e14-init-hidden" id="addProduct-bs9xtZPW-unlinked">Buy Now</span></span></td></tr><tr><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">Through Hole Resistor, 1 kohm, 500 mW, ± 1%</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">TT ELECTRONICS / WELWYN</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">2</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;"><span><span class="e14-init-shown e14-product-link-buynow" id="addProduct-PQtlguuR-linked" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=1099893~2&amp;nsku=78R4867~2&amp;COM=noscript" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=1099893~2&amp;nsku=78R4867~2&amp;COM=noscript" target="_blank">Buy Now</a></span><span class="e14-init-hidden" id="addProduct-PQtlguuR-unlinked">Buy Now</span></span></td></tr><tr><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">Red LED, Through Hole, 5mm, 20 mA, 2.1 V</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">LED TECHNOLOGY</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">1</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;"><span><span class="e14-init-shown e14-product-link-buynow" id="addProduct-XGFjIcRv-linked" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=1208853~1&amp;nsku=97K4136~1&amp;COM=noscript" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=1208853~1&amp;nsku=97K4136~1&amp;COM=noscript" target="_blank">Buy Now</a></span><span class="e14-init-hidden" id="addProduct-XGFjIcRv-unlinked">Buy Now</span></span></td></tr><tr><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">Tactile Switch, 12mm, Yellow, Top Actuated, Through Hole, Round Button, 24 VDC, 50mA</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">Omron</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">1</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;"><span><span class="e14-init-shown e14-product-link-buynow" id="addProduct-6DoKtqG0-linked" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=1960971~1&amp;nsku=52F3557~1&amp;COM=noscript" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=1960971~1&amp;nsku=52F3557~1&amp;COM=noscript" target="_blank">Buy Now</a></span><span class="e14-init-hidden" id="addProduct-6DoKtqG0-unlinked">Buy Now</span></span></td></tr><tr><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">Tactile Switch, 12mm, Red, 12 VDC, 50mA</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">Multicomp</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;">1</td><td style="border:1px solid black;border:1px solid #C6C6C6;padding:6px;"><span><span class="e14-init-shown e14-product-link-buynow" id="addProduct-NDj2MU2O-linked" style="white-space:nowrap;"><a class="jive-link-product-addtolist" href="https://www.element14.com/community/view-product.jspa?fsku=2543104~1&amp;nsku=67P3652~1&amp;COM=noscript" target="_blank"><span class="pf-widget-map pf-productlink-cart-icon"></span></a><a class="jive-link-product pf-embedded-product-link" href="https://www.element14.com/community/view-product.jspa?fsku=2543104~1&amp;nsku=67P3652~1&amp;COM=noscript" target="_blank">Buy Now</a></span><span class="e14-init-hidden" id="addProduct-NDj2MU2O-unlinked">Buy Now</span></span></td></tr></tbody></table><p style="margin:0;padding:0px;">&nbsp;</p><h2><span style="color:#3334ca;">Additional Parts:</span></h2><p style="margin:0;padding:0px;">&nbsp;</p><table border="1" class="jiveBorder" style="border:1px solid #000000;width:100%;"><thead><tr><th style="border:1px solid black;border:1px solid #000000;padding:2px;color:#ffffff;background-color:#6690bc;text-align:left;" valign="middle"><strong>Product Name</strong></th></tr></thead><tbody><tr><td style="border:1px solid black;border:1px solid #000000;padding:2px;">Desktop Power Supply</td></tr></tbody></table><p style="margin:0;padding:0px;">&nbsp;</p><p style="margin:0;"><br /><br /></p><div style="clear:both;"></div> <div style="font-size: 90%;">Tags: e14presents_karencorbeill, e14presents_makerkaren, the learning circuit 70: 555 timers - how bistable mode, 555 timers</div>