how can i connect a j type thermocouple to an arduino ? and how can i make my own amplifier ?
Use a proper chip like the MAX31855. They have all the cold-junction stuff, proper amps etc.
the MAX31855 is not an option for me as it can be used only with a k thermocouple...also i will have to order it and it will take time...i need to make my own..is it possible ?
From the data sheet
Versions Available for K, J, N, T, and E Type Thermocouples
I suppose you can DIY but I don't know how to.
Where are you? It doesn't normally take long to get stuff. Avnet supposedly have them in stock.