Hammond 161D40 1VA 40V Center-Tapped PCB Power Transformer

The 161D40 is a 1 VA low voltage power transformer for printed circuit board mounting, built with a single 115V primary rated for 60 Hz only. Its secondary delivers 40V centre-tapped at 20mA when the windings are used in series, or 20V at 40mA when they are connected in parallel. It suits OEM engineers and designers who need a board-level 40V C.T. or 20V AC source from a 115V line.

According to the part drawing, the primary connects across pins 1 and 2 and the two secondary windings sit on pins 3-4 and 5-6, each marked 20V / 25mA per secondary winding. The drawing lists a no-load secondary voltage of 23.83V ±2% per winding and an excitation current of 12mA max. @ 115V, 60Hz, pin 1 - pin 2. A red dot above pin 2 marks the mechanical winding start for manufacturing only and is not a polarity dot.

Construction follows the 160-161 Series design: a vertical mount, split bobbin transformer; 1 VA models in this series are concentric wound. Low primary-to-secondary coupling means no electrostatic shield is required. Insulation is Class B (130 degrees C) with a Hipot rating of 2,000V RMS, and the 161D40 drawing specifies a primary-to-secondary hipot test of 2000V, 60Hz, 1 sec.

Drawing dimensions for the 161D40 are A 1.000" ±0.031, B 1.360" ±0.031 and C 0.830" ±0.063, with pin size 0.018" x 0.041" ±0.005, E 1.200" ±0.031 and G 0.250" ±0.031 (2 places). The shipping weight is 0.13 lbs (0.06 kg).

The 161D40 is CSA certified (File # LR3902) and UL recognized (File #E207860), and it is listed as RoHS and REACH compliant. If the design must also run from 230V or 50 Hz supplies, the dual primary 115/230V counterpart in the ordering table is 160D40.