Building a simple tuned radio frequency (TRF) receiver is an easy job. TRF receivers work by tuning to the transmitting carrier frequency (duly amplitude modulated, of course) and amplifying them before feeding this RF to the detector stage. Three major types of AM receivers are:

1. The Crystal Radio Receiver: The crystal was actually an impure form of lead sulphide, called 'galena'. A spring was made to contact this crystal through a fine tip; thus as if working as a point contact diode. This was known as 'cat's whisker' in the past era. Acharya Jagadish Chandra Bose (and G. Marconi) devised this contraption. You will be surprised to learn that this radio consumed no external power supply. The induced current was sufficient to drive a high impedance crystal headphone. You can learn more here

A coaxial RF connector is an electrical connector designed to work at radio frequencies in the multi-megahertz range. RF connectors are typically used with coaxial cables and are designed to maintain the shielding that the coaxial design offers. Better models also minimize the change in transmission line impedance at the connection. Mechanically they provide a fastening mechanism (thread, bayonet, braces, push pull) and springs for a low ohmic electric contact while sparing the gold surface thus allowing above 1000 reconnects and reducing the insertion force. Research activity in the area of radio-frequency (RF) circuit design has surged in the last decade in direct response to the enormous market demand for inexpensive, high data rate wireless transceivers.

ALE/PROG: Address Latch Enable output pulse for latching the low byte of the address during accesses to external memory. ALE is emitted at a constant rate of 1/6 of the oscillator frequency, for external timing or clocking purposes, even when there are no accesses to external memory. (However, one ALE pulse is skipped during each access to external Data Memory.) This pin is also the program pulse input (PROG) during EPROM programming.

radio frequency transmitters plus the security of programmable card access for long-range access control with supported distances up to 200 feet away. The stand-alone unit is programmed using a built-in keypad and audio feedback so a computer is not required. Transmitters can be restricted based on time zones and/or gate location.

If you own multiple vehicles and need to carry the identification device with you, our portable "clicker" style transmitters can be utilized. Or if the same vehicle is used on a daily basis, you can utilize our "visor" style. Mounted on the overhead visor in the car, or the convenience of placing the transmitter on a key chain so it is always with you, the operation is simple and the information secure.

This is a precision ±15V regulator on a single side PCB.The circuit is based on EB-802 with design by zerosoft on www.headphoneamp.co.kr .I have replaced some components that easy to find in the market and design a new PCB that look like symmetry layout.But,you can replace the components with high quality component if you can find.