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Velleman Thermostat Mini kitVelleman Kits

Thermostat Mini kit

Specification Features:

  • Temperature range: +5C to +30C approx. (41F to 86F)
  • Relay power rating: 24VDC/AC 3A
  • Power supply: 12VDC / 100mA


The following alterations will allow you to increase the temperature range of the MK138. To make it suitable for use as an egg incubator thermostat (37.5) with a hysteresis of approximately 0.4.  You will need to change the value of these components.


  • R4 4K7 1% (Order Code 907-247)

  • R5 3k9 5% (Order Code 906-239)

  • R6 2K7 5% (Order Code 906-227)

  • R7 10M 5% (Order Code 906-610)

  • RV1 1K (Order Code 994-210)


Read the fully Illustrated Assembly Manual for MK138

PDF Download





Dimensions (PCB)

54 x 62mm



General purpose low-cost thermostat with NTC temperature sensor. Output operates relay with LED status indicator.


The Velleman MK138 is available as a ready built module VM137
Order Code Each 
MK138Velleman Thermostat Mini kit4.35 


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