How do I show the effects of putting a resistor in series with the primary of a transformer.Currently the transformer drops 120 to 6Putting the resistor on the 120 side what would happen? I am assuming it would drop the 120 down to some value which would then affect the secondary but I would like some numbers
if it has any noticeable effect, then it will get very HOT and burn out Transformers are basically lossless (95%) so adding resistors is basicaly stupid
Sounds like an interested question
An ideal transformer changes impedances by a ratio which is the square of its voltage ratio (which is also the winding ratio). So in your case you drop from 120V to 6V. The voltage ratio is 20:1. If we square that, we get a ratio of 400:1 for impedance transformation. This means a 400 Ohm resistor in the primary circuit will look like a 1 Ohm resistor in the secondary circuit. Please note that putting resistors in front of or behind transformers is generally not a good thing. It rarely ever makes things better and it almost always screws things up. If you need a different voltage, you have to change the ratio of the windings.
Placing a resistor in series with the primary of a transformer has the same effect as placing a resistor in series with a resistive load: that is, depending on how much current is flowing, there will be a voltage drop across the series resistor which decreases the voltage seen by the primary of the transformer and a corresponding drop in the voltage produced at the secondary. If there is no current flowing, then there is no voltage drop at the primary and no drop at the secondary. For example, your 120:6 transformer produces 6 volts at the secondary with 120 volts applied to the primary. Suppose your secondary load draws 1 ampere, then the power is 6 watts and the load is 6/1 6 ohms. This current reflected back to the primary is 1/20 .05 ampere. The secondary impedance reflected back to the primary is 120/1/20 2400 ohms. So any load in the secondary is reflected back to the primary by the square of the transformer turns ratio: 20^2 400 in this case. 6 ohms in the secondary is reflected back to the primary as 6 * 400 2400 ohms in the primary. So now you can compute the voltage seen by the primary when you place a resistor in series with it. If the reflected load is Rr and the series resistor is Rs then the voltage seen by the primary will be Vp 120 * Rp/(Rs +Rp) and the secondary voltage will be 1/20 of that.
