Product Overview
REMtech MSS2-1A12 Mercury Wetted Reed Relay - DIP-14 Package, 12V DC Coil, 1 Form A, All-Position Mount, Bounce-Free Contacts
Condition
Unused NOS. Sourced from an electronics distributor consolidating inventory. Clean and pristine with nothing out of the ordinary. In the photograph the black molded DIP body is marked REMtech MSS2 1A12, with a circled Hg mercury symbol at the left end, the caution line DANGER DO NOT OPEN across the bottom of the face, and the date code 26-02 printed vertically at the right end. A molded index dimple sits below the Hg symbol. The printing is crisp, the face is unscuffed, and the formed leads along both long edges are bright with no solder, flux, or bend marks. Against the millimeter ruler the body measures approximately 20 mm long. Evaluation: visual inspection only. Function testing not performed.
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Product Overview
The MSS2-1A12 is a mercury-wetted reed relay in a DIP-14 molded package, carrying the circled Hg symbol and the sealed-capsule warning DANGER DO NOT OPEN right on its face. Mercury wetting is what sets it apart from a dry reed: the contact closes without bounce and holds an ultra-low, stable contact resistance across its service life, which is why these parts ended up in precision measurement and high-fidelity signal switching rather than general-purpose control. The MSS2 series uses MYAD switch technology, so the relay can be mounted in any position on the board instead of the vertical-only orientation older mercury relays demanded. Coil nominal voltage is 12V DC with an approximate coil resistance of 500 ohms. The photographed piece carries the date code 26-02 and measures roughly 20 mm along the body against our ruler.
Key Features
- Contact form: 1 Form A (SPST-NO, single pole single throw, normally open)
- Coil voltage: 12V DC nominal
- Coil resistance: approximately 500 ohms (typical for MSS2 series)
- Switching capacity: up to 50W / 500V / 2A (typical MSS2 series rating)
- Contact material: mercury-wetted (Hg), zero contact bounce, stable low resistance
- Package: DIP-14 dual-in-line molded body, approximately 20 mm long against the ruler
- Mounting: all-position via MYAD switch technology
- No internal suppression diode, coil is not polarity-sensitive (MSS2-1A12 base variant)
- Body markings visible in the photo: REMtech, MSS2 1A12, circled Hg symbol, DANGER DO NOT OPEN, date code 26-02
Applications
- ATE technician building a low-noise signal matrix where a single contact bounce corrupts the reading
- Instrumentation engineer routing precision analog signals through a process control front end
- Audio builder wiring a preamplifier input selector or relay-ladder volume control that must switch silently
- Maintenance tech replacing an aging mercury reed relay on a legacy telecom or lab PCB and matching the original footprint
Frequently Asked Questions
What coil voltage and drive current does this relay need?
12V DC nominal. At approximately 500 ohms coil resistance, expect roughly 24mA of drive current. A 5V or 24V control line will not operate this relay reliably without level shifting or a dedicated drive circuit.
Does this one have an internal suppression diode?
No. The base MSS2-1A12, with no letter suffix, does not include an internal diode, and the coil is not polarity-sensitive. The MSS2-1A12B variant adds a suppression diode and the MSS2-1A12C adds a diode and an electrostatic shield. This listing is the base variant only, matching the MSS2 1A12 marking on the body in the photo.
Are there mercury handling, disposal, or shipping restrictions?
Yes. Mercury-wetted relays contain a small quantity of mercury, which is why the body carries the circled Hg symbol and the DANGER DO NOT OPEN line. Do not open, cut, or crush the capsule. Shipping and disposal are subject to hazardous material regulations that vary by jurisdiction, including local restrictions on mercury-containing devices. Verify compliance with your own requirements before ordering.
Is this the same part as the CP Clare MSS2-1A12?
The MSS2-1A12 part number is shared across the REMtech and CP Clare product lines, and MSS2 series specifications are consistent across them. The body photographed here reads REMtech. Verify pinout and coil specs against your target datasheet before installation.
It is unused stock but not function tested, so what am I actually taking on?
What you are getting is an unused NOS relay out of a distributor consolidation, graded by eye and photographed under our ruler so the markings, the leads, and the date code are all visible before you buy. What you are taking on is the electrical side: coil pull-in, release, and contact resistance were not measured here, and the mercury capsule is sealed inside a body stamped DANGER DO NOT OPEN, so nobody can inspect it without destroying the part. The photo is the spec for the outside; bench-check the coil and the contact before you drop it into a precision signal path. Shipping is $8 flat rate, free once your order passes $28, and orders leave our Idaho warehouse the same or next business day.
A sealed drop of mercury doing the one thing a dry contact never quite manages: closing without a stutter. Put it where a single bounce would ruin the measurement, and let it go back to the quiet work it was built for.
