Wiparat Circuit Electronics

My Friend want circuit Temperature Monitor for control relay. I find on internet , See to This Web http://www.mitedu.freeserve.co.uk/Circuits good article circuit. The Temperature Monitor use IC LM741 or IC 301 for test Temperature control relay switch.
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Using a thermistor in the position shown makes a heat activated sensor. A change in temperature will
alter [...]

Low Pass Active Filter by LM741
When you want to filter low frequency gives can change only. I thinks the Low Pass Active Filter circuit help you. Because of it uses IC LM741,then usable easy follow circuit image. We can fix the frequency is cut off get, by equipment value R1=R2 = R , and C1=C2=C [...]

60Hz Notch Filter by LM741
Source : 60Hz Notch Filter by LM741