what can i use to provide heat in a temperature control circuit

[Scritch]

Any suggestions to what i can use as a heat source

 

[ibrahim03]

A simple 60W or 100W light bulb can be used. It depends on the application. What exactly are you making?

 

[FvM]

Generally speaking, an electrical heater. (I guess, you already know.) For test purposes, it can be a small power resistor near to the temperature sensor.

 

[Scritch]

it's design for a baby's incubator

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it's design for a baby's incubator

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it's design for a baby's incubator

 

[ZASto]

There are specialized heated mats for incubators. Also, you will have to consider Oxygen measurement and regulation, as well as efficient ventilation.