🔧 CD4047 Timer Calculator

User Guide – Astable & Monostable Modes

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📌 What This Calculator Does

Design timing circuits for the CD4047 CMOS multivibrator IC. Choose Astable (oscillator) or Monostable (one-shot pulse). Two calculation modes: Standard (R+C → output) or Find Resistor (target frequency + C → R).

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⚡ Quick Start (3 Steps)

• 1️⃣ Select Mode – Astable / Monostable
• 2️⃣ Choose Calc Mode – Standard / Find Resistor
• 3️⃣ Enter Values → Calculate – Get results instantly

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🔘 Mode Selection

Mode	Formula	Typical Use
Astable (Free-running oscillator)	f = 1 / (4.4 × R × C)	LED flasher, clock generator, tone
Monostable (One-shot pulse)	T = 2.2 × R × C	Time delay, relay timer, debounced switch

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📊 Calculation Modes

📐 Standard Mode

You know R and C → calculator gives frequency or pulse width.

Example: R=100kΩ, C=0.1µF → f = 2.27kHz

🔍 Find Resistor Mode

Target frequency/pulse and fixed C → calculator gives required R.

Example: Target 1kHz, C=0.1µF → Required R = 2.27kΩ

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📋 Output Fields Explained

• Frequency (f) – Hz / kHz / MHz (Astable only)
• Period (T) – Time for one cycle (Astable only)
• Pulse Width (Tw) – Output HIGH duration (Monostable only)
• Required Rₜ – Calculated resistor (Find Resistor mode)
• Time Constant (RC) – Product R × C

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⚠️ Practical Limits (CD4047)

• Resistor (R): 10 kΩ – 10 MΩ
• Capacitor (C): 100 pF – 100 µF
• Frequency range: 0.001 Hz – ~1 MHz
• Supply (Vdd): 3V – 15V
• Duty cycle (Astable): ~50% (fixed)

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❓ Troubleshooting

Problem	Solution
"—" or no result	Check R > 0 and C > 0
"Out of range"	Adjust capacitor value up or down
Frequency too low	Decrease R or C
Frequency too high	Increase R or C

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🧭 Pin Reference (CD4047)

• Pin 1 – C (timing capacitor)
• Pin 2 – R (timing resistor)
• Pin 3 – RC Common
• Pin 4,5 – Astable inputs
• Pin 6,8 – /Trigger inputs
• Pin 7 – Vss (GND)
• Pin 10,11 – Q Osc, /Q Osc
• Pin 12 – Q (output)
• Pin 13 – /Q (inverted output)
• Pin 14 – Vdd (+3V to 15V)

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📐 Formulas Summary

• Astable: f = 1 / (4.4 × R × C)
• Monostable: T = 2.2 × R × C

💡 Tip: Choose a standard capacitor, then use "Find Resistor" mode – resistors are easier to fine-tune.