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This Selector Antennas using PIN Diodes Circuit Diagram selector antennas uses PIN diodes, was designed using common components and is very useful when used various external antennas, this antenna selector uses PIN diodes that eliminate disadvantages of mechanical switches especially at high frequency.  Capacitors C1 to C4 and C9 are used to prevent the input and output circuit DC. Shock L1 to L5 prevent leakage of HF signal.Shock L1 to L5 can be wound on a ferrite core, using enameled copper wire of 0.3 mm in diameter, two rounds will suffice for entries for VHF and UHF 5 (1 mH is required for VHF and UHF about 5 uH). The circuit was designed for antenna input impedance of 50 or 75 ohms. Selector Antennas using PIN Diodes Circuit Diagram

Most 3-terminal active components can be  tested statically using just an ohmmeter. But  when you have a lot of these devices to test,  the procedure soon becomes boring. That’s  where the idea came from to combine fast,  easy testing for these types of device into a  single instrument. The unit described here enables you to test  NPN and PNP bipolar transistors, N-or Pchannel FETs or MOSFETs, UJTs, triacs, and thyristors. Regardless of the type of device, the  tests are non-destructive. Universal connectors allow testing of all package types, including SMDs (up to a point). The unit lets you  change from one type of device to another in  a trice. It avoids using a multi-pole switch, as  they’re too expensive and hard to find. Circuit diagram : Universal Tester for 3-pin Devices Circuit Diagram Here’s how to build a versatile instrument at  a ridiculously low cost. IC1 is a 4066 quad CMOS switch which will let us switch between bipolar transistors and FETs. LEDs D1–D4 tell us abou...