Reed Switch LM393 Magnetron Module Reed Sensor

Reed Switch LM393 Magnetron Module — Digital and Analogue Output

This reed switch module combines a normally-open reed switch with an LM393 comparator to give both a digital TTL output and a raw analogue output from the same board. When a magnet comes within range, the reed closes, the comparator output snaps low, and the onboard LED lights — giving instant visual confirmation without a multimeter. The 3.3V to 5V supply range makes it compatible with Arduino, ESP32, and Raspberry Pi GPIO without a level shifter on the digital output pin.

• Normally-open reed switch — closes reliably in the presence of a magnetic field
• LM393 comparator output — clean TTL digital signal, 15mA drive capacity
• Analogue output pin — raw reed switch voltage for analogue ADC reading
• 3.3V–5V supply range — direct GPIO connection on Arduino and ESP32
• Onboard indicator LED — visual trigger confirmation without code

How close does a magnet need to be to trigger the reed switch?

Sensitivity depends on the magnet strength. A standard 10mm neodymium disc magnet triggers most reed switches from 10–15mm away. A weaker ferrite magnet requires 3–5mm. The reed switch inside this module is a standard 2x14mm glass capsule — typical activation distance with a neodymium magnet is around 8–12mm through air.

Can you use the reed module for door or window sensors?

Yes — this is one of the most common reed switch applications. Mount the module on the door frame and a small neodymium magnet on the door itself. When the door opens, the magnet moves away, the reed opens, the digital output goes high, and an Arduino interrupt or input read detects the state change.

Best for

Door and window alarm sensors, liquid level float switches, magnet proximity detection, RPM counting on rotating shafts, mailbox arrival alerts, non-contact limit switches for CNC machines, and tamper detection in enclosures.

Why Kunkune

Shipped from UK stock. 60-day returns and no minimum order — buy one or a handful for multi-door setups. Fast Royal Mail delivery.

Buying in bulk? For orders of 10+ units or trade pricing, contact us for a custom quote.