PT4115 continuous conduction mode inductive step-down converter

The PT4115 is a continuous conduction mode inductive step-down converter, designed for driving single or multiple series connected LED efficiently from a voltage source higher than the total LED chain voltage. The PT4115 operates from an input supply between 6V and 30V and provides an externally adjustable output current of up to 1.2A. Depending upon the supply voltage and external components, the PT4115 can provide more than 30 watts of output power. The applications of the PT4115 include Low voltage halogen replacement LEDs, Automotive lighting, Low voltage industrial lighting, LED back-up lighting, Illuminated signs, SELV lighting, LCD TV backlighting.

BS170 - is used for the QRP rig PA

The 2N7000 PA was described in my blog message sometime ago. The BS170 by Fairchild can be also used for QRP rig PA. It is N-Channel Enhancement Mode FET. The Maximum Power Dissipation Pd is 830mW, therefore it can be suitable for QRP rig PA. The transmitter section of ADC-40 is the dual BS170 and it generates about 4watts with 13.8V power supply. The small heatsink is required to use BS170s for PA because it will be hot and drops the power. The PFR-3A is the triple BS170 for PA and generates 5 Watts with 12V power supply.