Originally posted by elias
View Post
I too have have seen all the effects you mention. And, like you, I haven't found OU either but I have had many an exciting time when I thought I may have. To answer your question: Consider a simple circuit consisting of a 24v battery, connected to the positive terminal a 12v 100mA bulb. That bulb is connected to the positive terminal of a 12v battery and the negative terminal of the 12v battery is connected to the negative terminal of the 24v battery completing the loop. The 24v battery is the power source for the circuit and the 12v bulb and 12v battery are the load. Because of the bulb current is limited in the circuit to 100mA.
Kirchoff's current law is a statement about the conservation of charge flow through a circuit: at no time are charges created or destroyed. This means that that, in this simple circuit, a 100 mA current(I) will flow from the positive terminal of the 24v battery, through the bulb, the 12v battery and back to the negative side of the 24v battery, lighting the bulb and charging the 12v battery in the process with 100mA of constant current. If you were to change the bulb to one rated at 12v 200mA, then the 12v battery would see a constant current of 200mA. Change the bulb to one rated at 12v 12watt and 1 amp of continuous current will flow throughout the circuit, lighting the bulb and charging the battery with one amp of current. The bulb is limiting the current in the circuit by conversion and that current is present at all points in the circuit.
Now add a switch into this circuit, you can either add it between the 24v positive terminal and the bulb (high side switch) or you can add a switch between the negative terminals of the 12v and 24v batteries (low side switch). Now you can interrupt the flow of current in the circuit by activating the switch, opening and closing the circuit. What happens when we replace the bulb with an inductor and rapidly switch the flow of current on and off. When the switch is closed the inductor converts the current into a magnetic field around the core of the coil, this limits the current through the circuit, as the field builds less current is diverted so more current becomes available to the circuit and to the 12v battery. This is what is known as the rise time of the inductor or the coil charge. Because of the way the inductor works, current rises in the circuit as the coil charges, therefor, current also rises in the charge battery.
When the switch goes open circuit, the flow of current from the 24v battery stops instantly. Charged inductors hate this, so the inductor will no take the role of the power source by collapsing the stored magnetic field inducing a reverse the polarity potential in order to keep current flowing in the same direction as when it was abruptly switched off. If there is no closed path for the energy you get a huge voltage spike so we include a path from the negative terminal of the 12v battery to the top of the coil to allow the energy induced by the collapsing field to dissipate as current through the 12v battery. The inclusion of the blocking diode creates a closed loop during the field collapse only and blocks when the switch or transistor is conducting, charging the coil.
Regards Lee...
. You don't think the magnet is needed then? Also you do not believe "voltage without current" theory?
Comment