Abstract: An arrangement for securing a power transistor (4, 6, 8) or like component which is inserted into a printed circuit board (2) in a vertically downward direction. The printed circuit board is housed in a housing (20, 60) whose lower part (20) has upstanding walls (24, 26) with pairs of vertical slots (4A & 4B, 6A & 6B, 8A & 8B). Spring clips 52 are inserted vertically downwardly so that their legs (52A, 52B) engage in the slots and their center portions (54) urge the transistors toward the upstanding walls so that the housing acts as a heat sink for the transistors, obviating the need for additional components. Also, since all insertion is performed vertically from above, assembly can be performed straightforwardly by an automatic insertion machine, resulting in more rapid assembly and increased reliability.

Abstract: A chopper circuit is series connected between a conventional ballast and the fluorescent lamps to provide a high frequency current to the lamps to increase and adjust the luminance thereof. The chopper circuit comprises a diode bridge with a transistor connected across the DC terminals thereof. The lamps are series connected with the AC terminals. A photocell is used in a feedback circuit to maintain constant lighting.