# How to calculate resistor values in the induction heating circuits?

#### vivek20055

Joined Nov 4, 2012
88
Hello,

I am new to electronic circuits?. I need to calculate resistor values in the following circuit. Can anyone suggest me something about this?

Thanks & regards,
Vivek Alaparthi

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#### wayneh

Joined Sep 9, 2010
17,504
A way to start is to estimate the voltages you want/need at various locations. Then use Ohm's law to calculate the combination of resistors needed to establish those voltages.

It helps in these calculations to know the impedances of the active components. For instance an op-amp will likely have inputs with at least 1MΩ impedance. That means you can control the voltage at that input with high value resistors, for example 47K, without much concern about current flowing into the input. The outputs have very low impedance.

Some components need specific current levels. For instance an LED needs about 20mA, or a transistor needs about 10% of the current it is controlling to be provided to the base of that transistor. Again, Ohm's law and Kirchoff's law are your friends.

#### vivek20055

Joined Nov 4, 2012
88
i am really confused with this ...!!

#### wayneh

Joined Sep 9, 2010
17,504
Please stop creating multiple posts on this same circuit! The mods should and will close the other ones.

Please also provide some context to your problem: What are you trying to do, and what have you done so far? Where did this circuit come from and why are the components not labeled? Is this for school? Why is a beginner attempting and struggling with such a difficult circuit?