Gold-Plated Industrial Bimetal Thermostat Switch (TO-3 Style Mount)
Industrial Electronic Component / Thermal Cutoff · Yellow Gold (Pure electroplated layer on internal contacts and external terminals)
Purity: 24K Gold Plated (estimated 99.9% purity of the outer layer only)
Type
Industrial Electronic Component / Thermal Cutoff
Purity
24K Gold Plated (estimated 99.9% purity of the outer layer only)
Gold Type
Yellow Gold (Pure electroplated layer on internal contacts and external terminals)
Weight
5 - 10 grams (Total weight; gold content is negligible)
Description
An industrial-grade bimetallic temperature control switch. While the exterior appears to be steel and aluminum, high-reliability versions of these switches utilize a thin gold plating on the internal electrical contacts and external spade terminals to prevent oxidation and ensure low electrical resistance over thousands of cycles.
Key Features
Fastened mounting flange (TO-3 style), spade terminals, bimetallic disc housing, and gold-plated contact points for signal-level switching.
Color & Finish
Silver-toned steel base with dull gold-tone oxidation on the contact terminals; industrial matte finish
Hallmarks & Stamps
Part numbers 'KSD1' and temperature ratings (e.g., '190') visible on the top cap; no precious metal hallmarks
Dimensions Estimate
33mm length including mounting flange; 15mm diameter cap
Gemstones & Inlays
None; contains bimetallic disc and ceramic/metal internal structure
Clasp & Closure
Two spade-style terminal connectors for wire attachment; screw-hole mounting flange
Chain & Links
N/A (Rigid mounting plate and terminals)
Craftsmanship Details
Precision-stamped steel casing with epoxy-sealed base; high-tolerance internal bimetal calibration for specific temperature trip-points.
Authentication Indicators
Part number stamps indicate industrial manufacturing; lack of purity stamps confirms this is functional hardware, not jewelry.
Origin & Maker
Standard industrial manufacturers like KSD, Honeywell, or Texas Instruments (Sensata)
Era & Period
Contemporary Industrial (Late 20th Century to Present)
Age Estimate
Circa 1990s-2020s based on the plastic/epoxy seal and stamping style
Cultural Significance
Represents the 'invisible' gold that powers modern safety systems in appliances and aerospace technology.
Condition Notes
Fair to Good; shows signs of oxidation on terminals and surface wear on the mounting plate; suggests a 'pulled' or used status.
Value Estimate
Melt value is virtually zero (less than $0.05 USD of gold); functional resale value is $2 - $8 USD as a replacement part.
Care & Maintenance
Keep terminals clean of grease and oxidation; avoid bending the spade connectors; store in a dry environment.
Similar Items
KSD301 snap-action thermostats, ceramic thermal fuses, and gold-plated relay contacts.
Interesting Facts
Gold is used in electronics not for its beauty, but because it is the most non-reactive conductive metal, ensuring safety sensors like this don't fail due to rust.