DIY Six Stage Attenuator for High Frequency HF

If you have to deal with radio frequency more than very rarely, it is helpful if you can easily weaken the signals in discrete steps. 

So you can e.g. Bring the output signal of an HF generator to a different level than would only be possible with the generator's adjuster. 

There are many applications for a concealer when comparing or repairing receivers or with radio devices. Unfortunately, professional attenuator are quite expensive. 

Doing it yourself is worthwhile here because expensive electronics are not required

The Circuit Diagram of Six Stage Attenuator from Elektor Elektronic July Edition 2017 in Germany language 

Circuit Diagram

PCB Lay Out

Final Six Stage Attenuator Prototype with aluminum case

With Six Stage Switches for 0..31 dB in 1 dB Step

Prototype Final

Frequency Response 0....-31 dB

Radio Straight or Crystal Radio for Science Project or Hobbyist

OA70 / IN34 / IN60 is Germanium Radio, choose only one type.
Antenna high from Ground is high is possible, ground is a must to Steel Water pipe, or making one from a piece of copper approximately 1 meter down to the ground, so will be voltage between ground and radio wave pick up by antenna.

I have build this Radio and connected input speaker to line input notebook and running with Open Lab software and can pick up Radio Signal from about 6 km air distance.

====+  Parts List for   +====

10 nF                              1   Capacitor


VC 500 pF                      1   Variable Capacitor


OA70/IN34/IN60             1


 GND                               1   GND
Termination Ground

108 Turns,12 Turns        L Tap between 108 Turns and 12 Turns

8-2000 Ohm  1   SPKR or Earphone 8 - 2000 Ohm , you can get this in junk shop or at ebay.com

RF Connector Male and Female For Antenna Connection
 

50 Ohm Coaxial cable for Antenna


Electronic Project Box

Antenna for LW,MW,SW and AM 

Sun Switch With Transistor 2N3055

2N3055 is Power Transistor and Amplifier Transistor for General Purpose and can act as Photo Transistor by cutting the "hat cover" of this transistor. This photo transistor function of 2N3055 can be taking the advantage as switching function with transistor. This circuit using 2 transistor which is 2N3055 and BD139. If there is no sun light or the light is not enough for Transistor 2N3005 to deliver, so R1 will give current to TR2 BD139 ,and this transistor will turn on Lamp on the Output of Circuit.

If The Sun Light which flows to "hat cover" of TR1 2N3055 enough, TR1 will deliver and will grounded Base of TR2 BD139 and will Turn Off The Lamp.R2 and P1 will improve switching system of the Transistors and The Light of Lamp Intensity could be regulated by P1.

At the below figure is Stripboard or Veroboard for the circuit. This Veroboard using DIY LC software. 

Parts Lists of Components :
Transistor TR1 2N3055

Transistor TR2 BD139

  
Resistor R1 4K7
Resistor R2 10K
Trimmer Resistor P1 1M
Lamp 9 V / 400 mA
Battery 12 V and Case battery
 

Universal PCB
  
Box  for the Circuit

Iridium Extremem 9575 Satellite Phone

• Extreme Satellite Phone - The Smarter, Tougher Satellite Phone. Iridium Extreme® combines market-leading toughness with an unmatched feature set including location awareness and a fully integrated SOS button with emergency response service — all in one compact handset.

The Iridium Extreme is the toughest handset ever from the only company that offers real global, real mobile, real reliable communications. Engineered with more features and more accessories than any other satellite phone on the market, Iridium Extreme puts more innovative capability - and more ways to connect than ever before - into the hands of people everywhere. 

Standardized: A highly capable handset needs a highly capable network to empower it. Iridium Extreme is built with the same reliable voice and data capability that Iridium users have come to trust, and backed by the world's only satellite network that commands real global coverage, pole to pole. Optimized: From desert to mountain, jungle to tundra, Iridium Extreme puts more powerful capability into the hands of people, around the world. 

It has more features and accessories than any other satellite phone. It is the only one with real time tracking. And it can connect with Iridium AxcessPoint to create a Wi-Fi hotspot to keep in touch on your trusted devices - everywhere. Ruggedized: No other phone in the world has more guts or grit than Iridium Extreme. 

It is the first phone with military-grade 810F durability. It is dust proof, shock and jet-water resistant. From emergency crews and paramedics to military personnel and government operations, Iridium Extreme is built for the world's toughest, highest usage customers to make the connections that matter under the harshest conditions, anywhere on the planet.

Get Raspberi Pi 4 Tiny Single Board computer with highly efficient function

Raspberi Pi 4 , tiny computer with support 4K dual display monitor , choice of RAM from 1GB, 2GB, 4 GB, high speed Giga bit ethernet, with wireless networking and bluetooth support. 

Faster more Powerfull

Better Processor ,Faster data transfer speed,with fanless and low power supply for this tiny single board computer. Have 2 Port USB 2 ports and USB 3 ports, make transfer data ten times more faster. With application for robot brains, smart home hub, media centre, networked AI core, factory controller, and much more. Works compatible with old Raspberi model.

Amherst Researchers from University of Massachusetts , Tauhidur Rahman and Forsaid Al Hossain has invented a portable surveillance device powered by machine learning - called FluSense- using Raspberi Pi 4 , which can detect coughing and sneezing crowd size in real time, then analyze the data directly monitor flu-like illnesses and influenza trends.

The FluSense creators say the new edge-computing platform, envisioned for use in hospitals, healthcare waiting rooms and larger public spaces, may expand the arsenal of health surveillance tools used to forecast seasonal flu and other viral respiratory outbreaks, such as the COVID-19 pandemic or SARS.(umass.edu)