RI-23B Glass Body Reed Switch SPST-NO Equivalent & Substitute Parts

Part Overview

The RI-23B is a glass body reed switch manufactured by Comus International, classified as SPST-NO (Single Pole Single Throw - Normally Open) with a switching capacity of 500mA at 140V AC and 200V DC. This component is rated for 10W power dissipation with an operate range of 28–52AT and operates across a temperature range of -55°C to 125°C.

The RI-23B is currently listed as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production or repair requirements. Substitute parts must maintain functional compatibility within the electrical and mechanical parameters specified for this application.

Key Parameters

Parameter	RI-23B Value
Circuit Configuration	SPST-NO
Current - Switching (AC/DC)	500mA
Voltage - Switching AC	140V
Voltage - Switching DC	200V
Power - Rated	10W
Operate Range	28–52AT
Operating Temperature	-55°C to 125°C
Mounting Type	Through Hole
Termination Style	Axial
Type	Glass Body Reed
RoHS Status	RoHS Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the RI-23B is determined by the following critical parameters:

Primary Compatibility Criteria:

Circuit configuration must be SPST-NO
Switching current must be 500mA (AC/DC) or higher
Switching voltage AC must be 140V or higher
Switching voltage DC must be 200V or higher
Rated power must be 10W or higher
Mounting type must be Through Hole with Axial termination
Component type must be Glass Body Reed

Secondary Compatibility Criteria:

Operate range overlap or containment with 28–52AT
Operating temperature range must encompass or match -55°C to 125°C
RoHS compliance status

Substitutes are grouped into two categories:

Category 1: Direct Comus International Series Substitutes Parts from the RI-23 and RI-23GP series maintain identical electrical ratings and physical form factors. These parts differ only in operate range specifications.

Category 2: Cross-Manufacturer Littelfuse Substitutes Parts from Littelfuse MDCG-4, MDSR-4, and MARR-5 series meet or exceed the primary electrical and mechanical requirements. These parts may have variations in operate range, physical dimensions, and switching time characteristics but maintain functional compatibility within the specified parameter envelope.

Parameter Comparison

Part Number	Manufacturer	Status	Circuit	Current (mA)	Voltage AC (V)	Voltage DC (V)	Power (W)	Operate Range (AT)	Temp Range (°C)	RoHS
RI-23B	Comus International	Obsolete	SPST-NO	500	140	200	10	28–52	-55 to 125	Compliant
RI-23GP-3540	Comus International	Active	SPST-NO	500	140	200	10	35–40	-55 to 125	ROHS3 Compliant
MDCG-4-17-28	Littelfuse Inc.	Active	SPST-NO	500	140	200	10	17–28	-40 to 125	ROHS3 Compliant
MDCG-4-17-38	Littelfuse	Active	SPST-NO	500	140	200	10	17–38	-40 to 125	ROHS3 Compliant
MDCG-4-22-28	Littelfuse Inc.	Active	SPST-NO	500	140	200	10	22–28	-40 to 125	ROHS3 Compliant
MDCG-4-22-33	Littelfuse Inc.	Active	SPST-NO	500	140	200	10	22–33	-40 to 125	ROHS3 Compliant
MDCG-4-22-38	Littelfuse Inc.	Active	SPST-NO	500	140	200	10	22–38	-40 to 125	ROHS3 Compliant
MDSR-4-27-33	Littelfuse Inc.	Active	SPST-NO	500	—	200	10	27–33	-40 to 125	ROHS3 Compliant
MARR-5-12-38	Littelfuse Inc.	Active	SPST-NO	500	265	1000	10	12–38	-75 to 125	ROHS3 Compliant
MARR-5-17-38	Littelfuse Inc.	Active	SPST-NO	500	265	1000	10	17–38	-75 to 125	ROHS3 Compliant
MARR-5-27-38	Littelfuse	Active	SPST-NO	500	265	1000	10	27–38	-75 to 125	ROHS3 Compliant

Engineering Selection Recommendations

Tier 1: Preferred Substitutes (Comus International Series)

RI-23GP-3540 is the primary recommended substitute. This part maintains identical electrical specifications (500mA at 140V AC / 200V DC, 10W rated power) and physical form factor as the RI-23B. The operate range of 35–40AT falls within the RI-23B's 28–52AT specification envelope. RI-23GP-3540 is currently in active production status with ROHS3 compliance certification, ensuring long-term supply availability and regulatory alignment.

Tier 2: Cross-Manufacturer Substitutes (Littelfuse MDCG-4 Series)

MDCG-4-22-38, MDCG-4-22-33, MDCG-4-17-38, and MDCG-4-22-28 are functionally equivalent alternatives. All maintain 500mA switching current at 140V AC / 200V DC with 10W rated power. These parts are in active production with ROHS3 compliance. The operate range specifications (17–38AT, 22–38AT, 22–33AT, 22–28AT) provide coverage across the RI-23B's 28–52AT range. Physical dimensions differ slightly (1.590" overall length versus RI-23B's 1.811"), requiring verification of board layout compatibility.

Tier 3: Extended Voltage Substitutes (Littelfuse MARR-5 Series)

MARR-5-27-38, MARR-5-17-38, and MARR-5-12-38 exceed the RI-23B's voltage specifications (265V AC / 1000V DC) while maintaining 500mA switching current and 10W rated power. These parts are suitable for applications requiring higher voltage margins. Operating temperature range extends to -75°C, providing enhanced low-temperature performance. Physical dimensions are larger (2.235" overall length), requiring board layout verification.

Tier 4: DC-Only Substitute (Littelfuse MDSR-4 Series)

MDSR-4-27-33 is suitable only for DC applications. This part maintains 500mA switching current at 200V DC with 10W rated power but lacks AC voltage specification. The operate range of 27–33AT overlaps the RI-23B specification. Use this substitute only when AC switching capability is not required.

All recommended substitutes carry ROHS3 compliance certification and are currently in active production status, ensuring regulatory compliance and supply chain continuity.

Frequently Asked Questions (FAQ)

Q1: Can RI-23GP-3540 directly replace RI-23B in all applications?

RI-23GP-3540 maintains identical electrical ratings (500mA at 140V AC / 200V DC, 10W power) and physical form factor as RI-23B. The operate range of 35–40AT is contained within RI-23B's 28–52AT specification. Direct substitution is valid for applications where the magnetic field strength falls within the 35–40AT range. Applications requiring operation below 35AT or above 40AT require evaluation of alternative parts with broader operate ranges.

Q2: What is the difference between operate range and release range?

Operate range (measured in Ampere-Turns, AT) specifies the magnetic field strength required to close the reed switch contacts. Release range specifies the magnetic field strength at which contacts open. The RI-23B operates at 28–52AT and releases at 12–29AT. Substitute parts must have operate ranges compatible with the magnetic field strength present in the application.

Q3: Why do Littelfuse MDCG-4 parts have different physical dimensions than RI-23B?

MDCG-4 series parts have an overall length of 1.590" (40.39mm) compared to RI-23B's 1.811" (46.00mm). This dimensional difference results from different glass tube construction. Both maintain identical electrical specifications and Through Hole Axial termination. Board layout and component spacing must be verified before substitution.

Q4: Can MARR-5 series parts substitute for RI-23B in standard 140V applications?

MARR-5 series parts (265V AC / 1000V DC) exceed RI-23B voltage specifications and are functionally compatible. However, these parts are physically larger (2.235" overall length) and have different switching time characteristics (0.75ms operate time versus RI-23B's 0.25ms). Substitution is valid from an electrical standpoint but requires verification of board layout and timing-critical circuit behavior.

Q5: Is MDSR-4-27-33 suitable for AC applications?

MDSR-4-27-33 is specified for DC switching only (500mA at 200V DC). This part lacks AC voltage specification and should not be used in AC switching applications. Use MDCG-4 or MARR-5 series parts for AC/DC dual-capability requirements.

Q6: What compliance certifications apply to substitute parts?

All recommended substitute parts carry ROHS3 compliance certification. RI-23B carries RoHS Compliant certification. Both certifications confirm compliance with Restriction of Hazardous Substances directives. All parts are REACH Unaffected and carry EAR99 ECCN classification.

Q7: How does operating temperature range affect substitution?

RI-23B operates across -55°C to 125°C. MDCG-4 and MDSR-4 series parts operate across -40°C to 125°C, with a reduced low-temperature limit of 16°C. MARR-5 series parts operate across -75°C to 125°C, providing extended low-temperature capability. Substitution is valid when the application's temperature requirements fall within the substitute part's specified range.

Q8: Are there inventory considerations for substitute selection?

Current inventory levels are: RI-23B (963 pcs), RI-23GP-3540 (788 pcs), MDCG-4-22-28 (4400 pcs), MDCG-4-22-38 (1618 pcs), MARR-5-27-38 (983 pcs), MARR-5-17-38 (979 pcs), MARR-5-12-38 (943 pcs), MDCG-4-22-33 (766 pcs), MDCG-4-17-38 (717 pcs), MDSR-4-27-33 (686 pcs). MDCG-4-22-28 offers the highest current availability. Inventory levels are subject to change and should be verified at time of procurement.

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