From extreme temperatures to high‑vibration environments, reed switches excel where other sensors fall short. Learn how their hermetically sealed design, fast switching and long life make them an essential component across automotive, industrial and smart‑device applications.
If there are particular areas you need help with, feel free to skip to any of the following sections:
- Introduction
- Key Electrical Parameters
- Benefits of Reed Switches
- Applications and Markets
- Reliable Source
- Summary
Introduction
Reed switches are electromechanical devices actuated by a magnetic field. Two ferromagnetic blades sealed in glass either close (NO) or open (NC) when a magnet approaches, providing galvanic isolation and hermetic protection against corrosion and arcing. They’re ideal for harsh, dusty, or wet environments across a wide temperature range.
Key Electrical Parameters
- Pull-In (PO): Field/current/voltage (or AT) at which contacts close; typically specified as a maximum.
- Drop-Out (DO): Point at which contacts open (release/reset).
- Hysteresis: Often expressed as DO/PI (%); useful to avoid chatter.
- Contact resistance: Typically, contact resistance for a reed switch is ~ 70 mW, (10 to 25 mW of which is the actual resistance across the contacts).
- Dynamic contact resistance: Measured during operation to assess true contact condition.
For a more in-depth explanation of these and other key parameters, jump to the blog: Basic Electrical Parameters of Reed Switch Products.
Pro tip: Saturate the reed with a strong magnetic field before tests for consistent PI/DO readings.
Benefits of Reed Switches
Hermetically sealed, galvanically isolated contacts
Operate in liquids, gases, dust, and radiation.
Zero power
Zero power to hold its off state; low control power (~50–200 mW) for relays.
Fast switching
(~0.5–1.5 ms) with low resistance (~0.05–0.15 Ω) and high insulation (10¹⁰–10¹² Ω).
Durability
10⁶–10⁸ cycles; shock tolerance to ~500 g; vibration to ~3 kHz at 15–20 g.
Temperature range
About −60 °C to +155 °C.
Load flexibility
from μW to ~120 W.
Tighter sensitivity bands
(e.g., 18–22 AT) than typical Hall sensors, plus inherent hysteresis useful in metering/positioning.
Applications and Markets
| Market | Application |
| Automotive/EV | Coolant/brake/washer level, emissions, TPMS modules, door/bonnet position, e‑bike systems. |
| Home and IoT | Door/window state, liquid level sensing, smart metering. |
| Industrial and Energy | Rain/wind/barometric sensing, sunshade position, solar, agricultural and construction machinery. |
| Test and Measurement | Reed relays (gated by TTL/CMOS/transistors) deliver billions of operations in ATE. |
Reliable Source
Standex Electronics Detect is the premier worldwide source for reed switch technology, offering one of the industry’s broadest portfolios of reed switches, sensors, and relays. With decades of engineering expertise and high‑volume global manufacturing, Standex delivers reliable, cost‑effective, and application‑ready solutions for projects of any size. From standard products to custom sensitivity ranges and packaging, Standex provides the performance, consistency, and partnership customers need to solve their toughest design challenges.
- Broad portfolio: magnetic reed switches, reed relays, and packaged reed sensors.
- Custom sensitivity bands and packaging to fit your mechanical and electrical constraints.
- High‑volume manufacturing and quality systems for consistent PI/DO and contact performance.
Summary
Hermetically sealed reed technology combines precision, reliability, and long life with minimal power. Whether you need a tiny switch, a packaged sensor, or a relay for ATE, partnering with an expert supplier speeds design‑in and ensures performance in the field.
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