HRDS Series - Single Shot Timer

Littelfuse Single Shot Relays
The HRDS Series combines an electromechanical relay output with microcontroller timing circuitry. It offers 12 to 230V operation in five options and factory fixed, onboard or external adjustable time delays with a repeat accuracy of ±0.5%. The output contact rating allows for direct operation of heavy loads, such as compressors, pumps, blower motors, heaters, etc. This series is ideal for OEM applications where cost is a factor.

Operation (Single Shot)
Input voltage must be applied before and during timing. Upon momentary or maintained closure of the initiate switch, the output relay energizes for a measured interval of time. At the end of the delay, the output de-energizes. Opening or reclosing the initiate switch during timing has no affect on the time delay. The output will energize if the initiate switch is closed when input voltage is applied.
Reset: Reset occurs when the time delay is complete and the initiate switch is opened. Loss of input voltage resets the time delay and output.

Access specifications, certifications, check availability and order parts below

Catalog #Input
Voltage (V)
Storage Temperature (F/C)Time Delay RangeSample capableCompare
HRDS12012VDCNon-isolated SPDT-40° to 85°C (-40°F to 185°F)0.1 - 10s onboard adjustableNo
HRDS313M24VDCNon-isolated SPDT-40° to 85°C (-40°F to 185°F)3m fixedNo
HRDS32124VDCNon-isolated SPDT-40° to 85°C (-40°F to 185°F)1 - 100s onboard adjustableNo
HRDS421120VACNon-isolated SPDT-40° to 85°C (-40°F to 185°F)1 - 100s onboard adjustableNo
HRDS430120VACNon-isolated SPDT-40° to 85°C (-40°F to 185°F)0.1 - 10s externally adjustableNo