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Bipolar timer

NE555 Working Principle

Learn how NE555 works with an illustrated explanation and practical readings.

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NE555 at a glance

Follow the labeled connections and functional stages

NE555 working principle: illustrated functional stages, basic circuit and connections
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How it works

3 stages · Explore one step at a time

Step 1 / 3

Power and control

Connect pins 8 and 4 to +5 V, pin 1 to ground. Use a 100 nF supply bypass and a 10 nF capacitor from CONT to ground.

Step 2 / 3

Build the timing network

RA = 10 kΩ, RB = 68 kΩ and C1 = 10 µF. Join pins 2 and 6 to the capacitor node; pin 7 connects to the resistor junction. The capacitor’s positive plate faces the timing node.

Step 3 / 3

Read the cycle

Nominal high time is 0.693 × (RA + RB) × C1 = 0.541 s. Low time is 0.693 × RB × C1 = 0.471 s. The LED flashes about once per second; tolerance changes the exact result.

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