circuit design added for week 1

week1/Readme.md

@@ -48,3 +48,71 @@ Passive components cannot amplify or generate power. They only **respond to** th
 ![Passive Components](./passive_components_symbols.png)
 
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+# 🔁 Use in a Timer Circuit
+
+# 🔧 555 Timer LED Blinker Circuit (Astable Mode)
+
+This project uses a 555 timer IC in **astable mode** to blink an LED on and off at a regular interval.
+
+---
+
+## 🧰 Required Components
+
+| Component       | Value            | Quantity |
+|----------------|------------------|----------|
+| 555 Timer IC    | NE555            | 1        |
+| Resistor R1     | 10 kΩ            | 1        |
+| Resistor R2     | 10 kΩ            | 1        |
+| Resistor R3     | 470 Ω            | 1        |
+| Capacitor C1    | 10 µF (electrolytic) | 1    |
+| LED             | Any color        | 1        |
+| Power Supply    | 5V – 9V DC       | 1        |
+| Breadboard + jumper wires | —      | —        |
+
+---
+
+## 🔁 How It Works
+
+The 555 timer is configured in **astable mode**, which means it continuously switches between high and low states:
+
+- The **output pin (pin 3)** alternates between HIGH and LOW.
+- This causes the **LED to blink** on and off.
+- The **timing interval** is determined by **R1**, **R2**, and **C1**.
+
+---
+
+## ⏱️ Blinking Frequency Formula
+
+To change the blink rate:
+
+T = 0.693 × (R1 + 2×R2) × C1
+
+
+Where:
+- `T` is the period in seconds
+- `R1`, `R2` in ohms
+- `C1` in farads
+
+---
+
+## 🔌 Circuit Schematic
+
+![555 Timer LED Blink Circuit](./555_blink_circuit.png)
+
+---
+
+## ✅ Assembly Tips
+
+- Ensure **pin 1** is connected to **GND**
+- **Pin 8** goes to **Vcc**
+- Make sure the **capacitor polarity** is correct (− side to GND)
+- Use a **current-limiting resistor (R3)** with the LED to prevent damage
+
+---
+
+This is a perfect beginner project to understand **timers**, **oscillation**, and **basic LED control**. Let me know if you'd like to simulate this or turn it into a PCB design!
+
+### Resources:
+
+https://elonics.org/adjustable-led-flasher-using-555-timer/
+