In this calculator, instead of entering resistor and capacitor values, you give target frequency, like 500 Hz or 1000 Hz...
Then what the calculator does:
- It take a bunch of standard capacitor values like 0.001 µF, 0.01 µF, 0.1 µF, etc.
- For each cap value it uses the same NAND/NOT gate formula:
f = 1 / (1.38 × R × C)
Rearranged to:
R = 1 / (1.38 × C × f)
- Then it calculates how much resistance will give you that exact frequency with that capacitor...
- So now you can look at the list, choose a capacitor you already have and use the matching resistor!
This is super useful when you want to hit some exact blinking rate, beep, tone or timer pulse.
This Calculator will give you:
- Possible R and C value combinations.
- Based on standard capacitor steps.
- Shows calculated R in ohms (to match nearest real resistor).
Works for:
- NAND Gate Oscillators (4011, 4093).
- NOT Gate Oscillators (4069, 4049, 74LS04).
- Any simple RC inverter-based square wave oscillator.

Reverse NAND / NOT Oscillator Calculator
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