Custom Search

Power Supply AM Farm Radio

Power Supply AM Farm RadioPower Supply AM Farm Radio Circuit Diagram

The affection of the ability accumulation is a Tamura 3FD-410 5V bifold primary/dual accessory transformer. These are accessible from for reasonable prices. Normally, the transformer's primary windings would be affiliated in alternation for 240VAC operation or in alongside for 120VAC operation. This ambit takes one of the primaries and repurposes it as a 120VAC secondary. For this to work, the agent should be somewhat over-rated, which it is in this case.

The two 5V accessory windings are accumulated in alongside and beatific to a arch rectifier and clarify capacitor to aftermath about 7VDC. This DC voltage is current-limited by a 150 ohm resistor and acclimated to drive two amber LEDs. The LEDs can be hot-glued to the central of the radio aloft the punch to accommodate punch lighting and power-on indication.

The 7VDC is additionally beatific to an LM317 adjustable voltage regulator IC. The LM317 commonly produces a minimum voltage of 1.7V, which is too aerial for this application. A alternation 1N4002 diode is acclimated to bead about .5V to aftermath a minimum voltage of 1.2V. The regulator is adapted so that the filaments accomplish at 1.5VDC.

The 90VDC B+ accumulation uses a arch rectifier beyond the transformer's additional primary ambagious to aftermath about 160VDC. The rectified DC is filtered through a brace of electrolytic capacitors and a alternation resistor. The resistor drops the B+ voltage to the appropriate 90V.

Via :