Step-Up Transformer

Compare primary and secondary voltage and current with a 1:2 ideal transformer.

V1 supplies a 10 V peak, 1 kHz sine wave. T1 has 10 primary turns and 20 secondary turns in ratio terms, and RLOAD = 1 kΩ terminates the secondary. Both positive winding terminals have the same polarity. Separate ground symbols give each side a numerical reference.

$$n=\frac{N_s}{N_p}=2$$ $$V_s=nV_p,\qquad I_p=nI_s$$ $$Z_{\mathrm{in}}=\frac{R_L}{n^2}$$

The secondary voltage is 20 V peak, secondary current 20 mA peak, and primary current 40 mA peak. Instantaneous input and output power agree for the ideal transformer.

Read the chart. Vpri is green and Vsec red. Ipri is blue and Isec purple. Coincident voltage traces in the 1:1 case are expected. The four-cycle display makes polarity, amplitude and phase easy to compare.

Try it. Change RLOAD’s Resistance to 2 kΩ. Voltage ratio stays fixed while both currents halve. Restore 1 kΩ. T1’s Primary coil turns and Secondary coil turns control the ratio; keep their polarity settings at 0 for this comparison.

Model limits. This turns-ratio model omits magnetizing current, leakage, winding loss, saturation and frequency limits. It is suitable for an ideal AC ratio demonstration. Use the separate Transformer with DC example to study turn-on and steady DC. The displayed ground references do not demonstrate safety isolation.