DIY Dirt Cheap Continuity Tester with LED + 555 IC

Hi, i wanted to have a continuity tester (my multimeter doesn't have a buzzer) so i don´t have to look away from the circuit I am testing to see the multimeters display. Although i wanted a buzzer i also added a LED and an on/off switch for late night tinkering "stealth mode"
I don´t have any engineering or electronics background (actually i am a surgeon), but i love to make stuff and i am self teaching electronics with the help from Google and instructables.com . This is my first instructable and English isn´t my native tongue, so bear with me please...


DISCLAIMER: If following this guide anything/anyone/yourself damages i shall not be held responsible.Do it at your own risk. Take all the safety measures (goggles, gloves, etc)

Step 1: Bill of materials:

-Highlighter (worn out)
-Pen
-Blue LED
-switch
-555 IC
-0.01uF ceramic capacitors= 2
-1uF electrolitic capacitor = 1
-180 k resistor = 1
-56 k resistor= 1 (i did it on the weekend with no opened stores, so i used 47k + 10k series resistors)
-Piezo buzzer= 1 (i used a Hycom HY-07 that i took from an old modem)
-Button cell batteries= 3
-Battery holder (from a cheap-o pen/flashlight i had)
-Wires


-Soldering Iron
-hot glue gun
-xacto knife

Comments

[jaesn]

Great Idea! Got to love the versatility of the 555 timer. Also, how great is the internet? I'm teaching myself electronics through the same method.