Antenna Handbook

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10 Best Professional Automotive Diagnostic Scanner 2021 By Brand

White LED Lamp Circuit

Make  this  solid-state pocket torch using a few of these white LEDs. The simplest approach is naturally to use a separate series resistor for each LED, which has an operating voltage of round 3.5 V at 20 mA. Depending on the value of the supply voltage, quite a bit of power will be lost in the resistors. 

The converter shown here generates a voltage that is high enough to allow ten LEDs to be connected in series. In addition this converter supplies a constant current instead of a constant voltage. 

A resistor in series with the LEDs produces a voltage drop that depends on the current through the LEDs. This voltage is compared inside the IC to a 1.25 V reference value, and the current is held constant at 18.4 mA ( 1.25V devided by 68Ohm)
The IC used is one of a series of National Semiconductor 'simple switchers'. The value of the inductor is not critical; it can vary by plus or minus 50 percent. 220 uH coil at 3.5 A is good choice. Almost any type of Schottky diode can also be used, as long as it can handle at least 1 A at 50 V. The zener diodes are not actually necessary but they are added to protect the IC. If the LED chain is opened during experiments, the voltage can rise to a value that the IC will not appreciate.

Circuit


PCB Layout



Component Layout



Parts Lists


source ; Elektor 

Free Energy : Centrifugal dynamic power generating system using a lever structure Patent

This patent of Centrifugal dynamic power generating system using a lever structure invented by Daniel Paul Gorney. 

The free energy concept is the system/machine that operate perpetual motion indefinitely and independently without any other source of fuel, electricity, or any other renewable energy source other than gravity energy.

The free energy magnitude is over unity concept. the free energy result must bigger than energy for running the system/machine itself.
                                                                                                                                       

DC Millivoltmeter with IC OP AMP 741

The Design of this DC Millivoltmeter presented here is a sensitive dc. electronic meter of several Megaohms input resistance and covering range from 5 Volt f.s.d to 5 mV f.s.d. 

This D.C. voltmeter designed to be used with 1 mA meter movement, this unit can be used as a pre-amplifier for a conventional test meter when switched to its 1 mA range for 5 V range. The range of meters from 5V f.s.d ,0.5V, 50mV, and 5mV f.s.d are provided, with input several Mega Ohm.


Best Long range 990 miles hd 1080p outdoor amplified hdtv digital tv antenna long range vhf uhf ?

Is it possible to get 990 miles or 1500 km  amplified outdoor antenna  from Broadcast TV stations ? The answers it is depends , if the broadcast stations have many repeaters it is possible for you to received from the long range TV stations , but you don't need 990 miles amplified antenna for this. And also there is no antenna in the market with 990 miles amplified Antennas with a gain of 990 miles are not available in the market and are very difficult to manufactured.

The antenna in the range 50-300 miles it is enough  with reasonable price, more gain in dB and more elements.  because the TV stations have repeaters.

So the choice is an antenna to receive long distances between 50-300 miles plus an amplifier.

I have selected 5 of the best antennas and amplifiers or boosters for this purpose, so can be your reference before you buy it.