By Suren Shirani
This is a super simple RF detector designed to indicate the presence of radio frequency signals. It uses a minimal number of components and can detect RF signals in a basic, easy-to-assemble format. Ideal for educational purposes, testing, or quick RF detection experiments.
- Detects RF signals using a simple diode-based rectifier.
- LED indicator lights up when RF is detected.
- Simple design using an LM358 op-amp, a few resistors, capacitors, and diodes.
- Minimal footprint suitable for hobbyist PCBs.
| Qty | Component | Value / Part Number |
|---|---|---|
| 1 | Capacitor | 0.1 µF (C1) |
| 1 | Capacitor | 1 µF (C2) |
| 1 | Resistor | 700 Ω (R2) |
| 1 | Resistor | 1 MΩ (R1) |
| 1 | Op-Amp | LM358D (U1) |
| 1 | LED | 2 V, 10 mA (D3) |
| 2 | Diode | 1N34 (D1, D2) |
| 2 | Screw Terminal | Antenna Input, 9 V Vcc Input |
| 5 | Testpoints | TP1 – TP5 |
- The antenna picks up RF signals from the environment.
- D1 and D2 rectify the RF signal.
- The rectified signal is filtered and amplified by the LM358 op-amp.
- When the signal exceeds a threshold, the LED (D3) lights up, indicating RF presence.
- Antenna Input → Connect your simple wire antenna or external source.
- Power Input → 9 V DC to the Power Rail Input terminal.
- Testpoints → Optional points for monitoring signals (Vcc, GND, op-amp input/output, LED).
- This is a basic RF detector; it does not measure signal strength or frequency.
- Designed for educational and experimental use, not for precision RF measurements.
- Use a simple wire as an antenna—length affects detection sensitivity.