Solar Charge Controller

Hello,

Following is the circuit I took from a site which I successfully built. But here's the question, I desire to compute transfer function of this feedback circuit. It would have been great if I would be having only R L C stuff. But since I am having 555 timer also, I am badly in need of your valuable suggestions for numerical computation of the transfer function i.e., Output voltage / Input Voltage.

The 555 is being used as a voltage sensor switch with separately adjustable cut-in and cut-out. The 7805 provides a 5V (poor) voltage reference to the 555, including biasing the two voltage comparators inside the 555 to (5/3)V and (2*5/3)V. The transfer function is left to you, but it is non-linear, and includes hysteresis.

The circuit is poorly thought out. Overly complicated for what it does. The adjustments overlap in way that makes it extremely difficult to get it set up initially. I would have done it differently.