FM Radio Station Microphonic Part 25

FM RADIO STATION MICROPHONIC PART 25

HOW DO YOU TRANSMIT VOICE WITHOUT A MICROPHONE?

This is a two transistor circuit that makes up a wireless FM radio transmitter with a remarkable feature - it transmits voice without a microphone! 

It uses a floppy coil that moves upon receiving the vibrations from speech or other sources.


"This means it will vibrate when bumped and will even pick up sounds such as talking, music and footsteps and transmit audio just like a microphone.

Forget the phone lines as they are not needed for this example. Build the circuit and use 7 turns of thin wire on an 8-10mm pen and see how the coil picks up every sound in the room. Simply connect a 9v supply and the circuit starts broadcasting. The coil should be 6t and 3mm diameter, using 0.5mm enamelled wire."

Source
http://www.talkingelectronics.com/projects/Spy%20Circuits/SpyCircuits-3.html

FM Radio Station Notes Part 24

FM RADIO STATION NOTES PART 24

TUTORIAL: How Radio Waves are Produced
http://www.youtube.com/watch?v=aAcDM2ypBfE#t=186

FM TRANSMITTER
As a reference to going even smaller and more simple, this schematic shows possibly the most simple one transistor FM radio voice transmitter design, using a common 2N2222 transistor and only three capacitors and two resistors. There's only 7 electronic parts total to this assembly plus batteries and the antenna. A power on/off SPST switch should be added to the schematic.

Parts List
R1 Resistor 4.7K
R2 Resistor 220 ohms
C1 Capacitor .01uf
C2 Capacitor 33pf
C3 Capacitor 6.8pf
L1 Coil
Electret Microphone
2 - 1.5 Volt Battery

A slightly modified version is at this web site:
http://www.sentex.ca/~mec1995/circ/fmt2.htm
http://www.sentex.net/~mec1995/circ/circuits.htm

FM RECEIVER
The video also includes a schematic diagram for a very simple matching two stage FM radio receiver. This battery driven radio has only two transistors, amounting to 6 electronic parts plus batteries, switch and antenna.

Parts List
R1 Resistor 12K
C1 Capacitor 220n
T1, T2 Transistor BF199
C Variable Capacitor
3 Volt Battery
SPST Switch
Earphones
Antenna

BF199 transistor data sheet
http://pdf1.alldatasheet.com/datasheet-pdf/view/2947/MOTOROLA/BF199.html

MOST SIMPLE FM TRANSMITTER
The simple FM transmitter circuit shown above is a spinoff of this project. It uses only one resistor, one capacitor, one transistor and one coil. The article is found all over the web. It has no microphone but the coil is so microphonic that it will pick up noises in the room via vibrations on a table. The circuit does not have any section that actively tunes the frequency. The transistor turns on via the 47k resistor and this puts a pulse through the 15 turn winding. The magnetic flux from this winding passes through the 6 turn winding and into the base of the transistor via the 22n capacitor. This pulse is amplified by the transistor and the circuit is kept active. The frequency is determined by the 6 turn coil. By moving the turns together, the frequency will decrease.  The circuit transmits at 90MHz which is at the low end of the 88 to 108 MHz FM band. It has a very poor range and consumes 16mA.

http://www.circuitlab.org/2013/02/schematics-easy-build-rf-transmitter.html

http://skema-elektronik.blogspot.tw/2011_02_01_archive.html

http://circuit-diagram.hqew.net/Simplest-RF-Transmitter-circuit-diagram_4095.html

http://www.talkingelectronics.com/projects/Spy%20Circuits/SpyCircuits-1.html

This Google search link will find a lot more simple FM radio transmitter schematics and projects.

SIMPLEST FM TRANSMITTER
Here's another link to a project claiming also to be the simplest FM transmitter ever made.
http://circuitsdiy.com/the-simplest-f-m-transmitter-ever-made/

This circuit has audio input and needs only 2 resistors and 3 capacitors plus a coil and transistor.

"For input from low power output devices, such as mobile, computer’s sound card, the value of the unlabeled capacitor is 0.1 or 104. For higher wattage outputs, the value is 0.01 or 103. An optional microphone pre-amp can be also added in this circuit to enable it transmit voice directly."

ANTENNA
One idea to create the small transmitter antenna is to use a small wheel bicycle used spoke from a children's bike available from a bike shop probably for free.

How to Change a Dark Detector into an FM Transmitter
http://www.buildcircuit.com/fm-transmitter-and-dark-sensor/

A dark sensor can be converted to a simple FM transmitter using a similar schematic layout.

The dark sensor will light the LED as the output indicator. The transmitter substituted a microphone for the LDR.

FM TRANSMITTER
This FM transmitter is very sensitive and it has transmitting range of 30 meters with a 9-volt battery. Reducing battery power will reduce transmitter range.

Comments given at the link about the transmitter
The circuit may work but it relies on a “Q-factor” from the coil and capacitor in the tank circuit to produce a high voltage.

This high voltage gives the circuit a good range. Firstly the coil and capacitor should be near each other. The coil should not have long leads. and a 22n capacitor should be across the supply to give the circuit better performance. The value of C2 is too high. It should be 10p. The coil should be 5 turns. The electret mic should not be connected directly to the base of the transistor.

FM Radio Station Specs Part 23

FM RADIO STATION SPECS PART 23 
FM Radio Station statement of operating specifications, characteristics and purpose

Specifications 
Radio Type - Transmitter
Band - FM
Frequency Range - 88-108 MHz
Frequency Selection - tunable
Transmit power - under 100 mW
Range - desktop within room
Antenna - 1.75" diameter mini loop wire strand
Applications - hobby, school electronics, toy
Use - intermittent, testing, educational
Type - Personal Non-commercial
Power - 3 volts low power
Audio Source - voice electret microphone
Power source - battery
Typical Broadcast Duration- 30 seconds
Location - desktop
Size - pocket portable
Cost $4

Objectives 
* to fulfill the requirements of electronics design lab
* testing fm transmitter characteristics
* learning principles of broadcast radio stations

Applications 
* Transmit short range robot speech
* Classroom radio station project
* Electronics lab requirement
* Baby monitor
* Wireless pickup for guitar or ukelele
* Wireless microphone/KTV Singing
* Hobby or toy

Conclusion The micro FM radio station is a learning toy with short desktop range, a 1.75" antenna, and power under 100 milliwatts. No license is needed.

FM Radio Station Shielding Part 22

FM RADIO STATION SHIELDING PART 22
Whenever a capacitive or conductive source such as a human hand is in proximity or touching the radio station transmitter board, it can alter the signal and cause the circuit to drift, shifting the frequency.

To remedy this effect, install ground shielding throughout the radio station's enclosure. Form a continuous sheet of tin foil from a roll of kitchen aluminum foil used for cooking. Cover the inside of the front face plate as well. Make sure it contacts the sides to make a firm electrical connection without movement. Inside the cabinet, attach a ground wire from the foil to the transmitter's board ground connection. An external ground may also be needed. Experiment for best results. 

Make sure all other internal cabinet components are insulated and cannot inadvertently short out to ground.

FM Radio Station Sensitivity Part 21

FM RADIO STATION SENSITIVITY CONTROL PART 21

Sensitivity circuit, adjust values as needed

This project installs a sensitivity control to the FM radio station. R1 is a static preset 1K ohm resistor as seen in the original schematic. Add an optional resistance with a 0 to 10K ohm variable potentiometer as shown. The variable potentiometer becomes the sensitivity control. Just dial in the amount required.

Calibrate the sensitivity control based on the sound source to improve the sensitivity and quality of the signal. The microphone will be the most sensitive when the value is at zero ohms. R1 is actually an optional resistor as shown. It's purpose is to limit the voice sensitivity, for example, a 10K resistor will resist the voice signal coming from microphone more as compared to the 1K resistor.

Life in the Galaxy

Stars in the galaxy

LIFE IN THE GALAXY
Way back when astronomer Drake formulated the famous Drake equation for life in the galaxy, he determined the number of intelligent civilizations in our galaxy alone to be around one million.

This week, astronomers recalculated that there are 11 billion possibly habitable planets in our galaxy, greatly upping the odds that we're not alone in the universe. Researchers used four years of data from NASA's orbiting Kepler telescope to compute how many planets lie in their solar systems' "Goldilocks zone," where surface temperatures support liquid water. They found that one in five sun-like stars harbors a roughly Earth-size planet in the habitable zone, and the nearest may be only 12 light-years away — possibly close enough for communication. Given the sheer number of candidate planets, says astronomer Geoffrey Marcy, "surely some of them have all the necessary attributes of life."

Worlds beyond the solar system harbor intelligent life

We believe as space telescopes improve in resolution and capability, it won't be long and we'll discover intelligent life in the galaxy. Those in-space galactic neighbors only a dozen light years away may provide world changing communications. Why not? Many of our space probes take decades to return useful information. Communicating with advanced civilizations where it takes 10 or 20 years for a steady stream of data to reach us will not be unusual.

Sources and References
http://theweek.com/article/index/254523/the-biggest-scientific-breakthroughs-of-2013

FM Radio Station Housing Part 20

The idea is to put the radio station electronics into the smallest tiny enclosure possible and have remaining space for expansions. The yellow project box is perfect for this application, at 2 3/8" high x 1 1/8" deep x 4 1/8" long. One key feature, not shown here, is the front panel design label, that notates various controls and functions. Notations on the front will line up with actual controls at the top and the sides.

Cabinet, board, battery, antenna, controls

FM RADIO STATION TINY HOUSING PART 20
Perhaps the smallest radio station on the air today, tiny "Whisper Radio FM 102" is  housed in a miniature cabinet with space for expansion.

Whisper Radio -
"To hear a whisper you need to shut out the noise of the world…"

The radio station housing is an insulated rectangular yellow polymer cabinet. Components on the inside include the main board on the left with protruding microphone at top and antenna on the left, plus a 9VDC battery over on the right side.

At the top left is the mic, and at the top right is the on/off toggle switch and a red LED power-on monitor light. The best feature of mounting the microphone this way is the shortness of the leads which are kept at only one fourth inch long, thus minimizing interference. The push through microphone, without extending the leads, creates the highest quality, best signal, and minimizes distortion.

The cabinet is "drilled" with a soldering iron that easily melts holes into the plastic. Keep the internal board to the left, close enough to the side wall but keeping clearance mounting space to include the antenna jack.

The cabinet is large enough for installing many added features described in previous posts, like the mute switch, on-the-air monitor, tone control, etc. Refer to the controls post and the index link for more details.

FM Radio Station Controls Part 9
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-controls.html

FM Radio Station Part 5 Index
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-part-5-index.html 

FM Radio Station Broadcast Part 19

SciFi broadcast on Whisper Radio FM 102

FM RADIO STATION BROADCAST PART 19
Whisper Radio FM 102 broadcast a science fiction program, The Experiment - the Adventures of Tom Volt, on Monday December 30th 2013 at 12:30 to 12:48 am. A transcript of the program's text is found at the link below. This is from the famous Tom Volt adventure series authored by science fiction and science fact writer Humanoido.

The story goes on about the opening up of a quantum door into an alternate reality by a small group of scientist and describes their ultimate experiences.

The Adventures of Tom Volt - the Experiment
http://humanoidolabs.blogspot.tw/2013/04/the-experiment.html

FM Radio Station Schematic V1.1 Part 18

FM RADIO STATION SCHEMATIC V1.1 PART 18

The new updated v1.1 schematic for the FM radio station adds polarity notation to the electret microphone, corrects the size of notation for C3, and cleans up the antenna A1 symbol. It corrects the notation for transistors as Q1 and Q2 instead of T1 and T2, and introduces scaling.

A larger percent size schematic is provided for better clarity.

For more details about the FM Radio Station, refer to the index link.

FM Radio Station Part 5 Index
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-part-5-index.html

FM Radio Station Electronics Part 17

FM RADIO STATION ELECTRONICS PART 17

This page assembles four important comparison electronic element views showing the FM Radio Station. The purpose is to check the components and their placements from the board to the schematic to confirm complete accuracy so the project can be duplicated.

At top left is the top side of the printed circuit board showing all components and their values.

At top right, the photo shows a back lit view with circuit traces.

At bottom left is the schematic diagram.

At bottom right is a photo of the bottom side, with photo reversal to match the top right back lit photo.

FM Radio Station Part 5 Index
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-part-5-index.html

Astronauts to Mars

ASTRONAUTS TO MARS
How soon will astronauts go to Mars? Those going on the trip are now making preparations. Several groups are in the race to Mars, including private industry and NASA. China wants to do everything on their own and does not want to participate. Other countries may join in the initiative to putting the first colonists on Mars.

Aiming for Time Travel to the Future
Spacecraft don’t launch directly at Mars; that would use up too much fuel. Instead, spacecraft launch towards the point that Mars is going to be in the future. They start at Earth’s orbit, and then raise their orbit until they intersect the orbit of Mars; right when Mars is at that point. The spacecraft can then land on Mars or go into orbit around it. This journey takes about 250 days.

Looking at the Mars chart, it looks like a very popular place with many USA and Russian spacecraft orbiting and landing there. A good number have failed to reach Mars. The closest Mars is to the Earth is around 35 million miles during a close and favorable opposition. Miss the closer oppositions every two years and the aphelion distance of Mars to the Earth can be a staggering 249 million miles away. The year 2018 is a good year to arrive at Mars when it's only 35.8 million miles away.

Here’s a list of Mars Oppositions from 2007-2020 (source)
Dec. 24, 2007 – 88.2 million km (54.8 million miles)
Jan. 29, 2010 – 99.3 million km (61.7 million miles)
Mar. 03, 2012 – 100.7 million km (62.6 million miles)
Apr. 08, 2014 – 92.4 million km (57.4 million miles)
May. 22, 2016 – 75.3 million km (46.8 million miles)
Jul. 27. 2018 – 57.6 million km (35.8 million miles)
Oct. 13, 2020 – 62.1 million km (38.6 million miles)

Data to the Year 2037
Date of Opposition
Feb 12 1995
Mar 17 1997
Apr 24 1999
Jun 13 2001
Aug 28 2003
Nov 07 2005
Dec 24 2007
Jan 29 2010
Mar 03 2012
Apr 08 2014
May 22 2016
Jul 27 2018
Oct 13 2020
Dec 08 2022
Jan 16 2025
Feb 19 2027
Mar 25 2029
May 04 2031
Jun 27 2033
Sep 15 2035
Nov 19 2037

Date of Closest Encounter
Feb 11 1995
Mar 20 1997
May 01 1999
Jun 21 2001
Aug 27 2003
Oct 30 2005
Dec 18 2007
Jan 27 2010
Mar 05 2012
Apr 14 2014
May 30 2016
Jul 31 2018
Oct 06 2020
Dec 01 2022
Jan 12 2025
Feb 20 2027
Mar 29 2029
May 12 2031
Jul 05 2033
Sep 11 2035
Nov 11 2037

Closest Distance (AUs / Millions of Miles)
0.67569 / 62.8
0.65938 / 61.3
0.57846 / 53.8
0.45017 / 41.8
0.37272 / 34.6
0.46406 / 43.1
0.58935 / 54.8
0.66398 / 61.7
0.67368 / 62.6
0.61756 / 57.4
0.50321 / 46.8
0.38496 / 35.8
0.41492 / 38.6
0.54447 / 50.6
0.64228 / 59.7
0.67792 / 63.0
0.64722 / 60.2
0.55336 / 51.4
0.42302 / 39.3
0.38041 / 35.4
0.49358 / 45.9

Space Telescopes

SPACE TELESCOPES
It looks like competition is heating up for the number of telescopes in space. In addition to Humanoido Lab's 15 mega space telescopes, the chart illustrates many more. Several countries have made space telescopes including the USA, UK, and Japan.

Extremely Powerful Telescopes Chronology
http://humanoidolabs.blogspot.tw/2013/12/extremely-powerful-telescopes-chronology.html 

FM Radio Station Tone Part 16

FM RADIO STATION TONE CIRCUIT PART 16

Here's a modification to make a tone selector switch for the FM radio station's electret microphone output. Changes for actual use require adjusting the 8.2K ohm resistor and the 1nF capacitor based on the voltage supply.

A tone selector switch is used as a high pass filter to provide some tone adjustment. The 47nF setting reduces the low frequency and puts more of the midrange into useful talk power.

For FM, a 1uF setting is used which provides more full range audio suited to FM voice.

The electret mic element inherently has a strong gain. The intensity of voice and the position of person speaking can be adjusted to provide the best gain without distortion. Experiment with distances and component values to find the best results.

http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-controls.html

FM Radio Station Part 5 Index
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-part-5-index.html

FM Radio Station Microphone Part 15

FM RADIO STATION MICROPHONE PART 15

Electret Microphone
http://sound.westhost.com/project93.htm

A typical electret microphone preamp circuit uses an FET in a common source configuration. The two-terminal electret capsule contains a FET which must be externally powered by supply voltage V+. The resistor sets the gain and output impedance. The audio signal appears at the output, after a DC-blocking capacitor.

THE MICROPHONE is an important part of the radio station. In a simplified circuit, it must deliver reasonable sound quality and provide a usable frequency response and audio level.

An electret condenser microphone (ECM) consists of a very light diaphragm (moving plate) and back plate (stationary or static plate) and has a permanent charge implanted in an electret material to provide polarizing voltage.

The principle of operation is that sound waves impinging on the diaphragm cause the capacitance between it and the back plate to change synchronously, this in turn induces an AC voltage on the back plate.

1. Foil Electret Condenser Microphone (also called Middle or Classic) - Type of condenser microphone where the electret material is the diaphragm. (Sometimes referred to as "Front" type.)

2. Back Electret Condenser Microphone -Type of condenser microphone where the electret material is the back plate.

3. Front Electret Condenser Microphone -Type of condenser microphone where the electret material is the inside of the case of the microphone.

"It must be realized that all electret mics (indeed, all mics) have one limitation we cannot readily change, and that is maximum SPL (Sound Pressure Level). Because electret capsules have an integral amplifier, there will always be a level where they will distort.

A capsule having a 10k feed resistor and supplied from a 15V supply will output well over 1V RMS quite easily, simply by having it close enough to your mouth as you speak loudly.

Even professional microphones (including dynamic types) are quite capable of 0dBm in close proximity to a floor tom or a loud singer. As a result, close vocal work, drums and brass instruments (trumpet, sax, etc) are capable of extremely high SPL, and are not really suitable candidates for electret mics. It is possible to get good performance at up to 115dB SPL quite easily - possibly more. 

Sensitivity
The sensitivity can be reduced, simply by reducing the value of the feed resistor. Again, there is a limit, as the internal FET amplifier can be driven into distortion regardless of what you do on the outside of the capsule. It is feasible to modify the capsule itself - but this is only possible with some models unless you are willing to make a few sacrifices (you can guarantee that you will ruin a couple in the process)." 

Frequency response
http://www.digikey.tw/Web%20Export/Supplier%20Content/PUI_668/PDF/PUI_ElectretCondenserMicrophone%20Basics.pdf?redirected=1

"Frequency response is the microphone's sensitivity performance in the frequency range of 0 to 20 kHz. Compared with the dynamic types, ECMs tend to have an extended response both at low and high frequencies, which is also smoother.In the case of dynamic types, the response limits are defined where the sensitivity has fallen by 3 dB relative to its value at 1 kHz. It is not stated in such terms for ECMs since they have a much wider frequency response." 

Usage

"To obtain the best results, avoid placing near reflective surfaces. If possible, mount in soft rubber to insulate from vibration. Treat ECMs as stat ic sensitive. Use specified heat sinking when soldering to ECMs. Use as little heat as possible for shortest time consistent with good joint. Avoid subjecting ECMs to high temperature and humidity that can degrade performance. The frequency response of ECMs may be too extended for communications application, in which case, it can be limited by suitable acoustic filtering in the intended housing or handset."

Microphone Setup
The legs on the electret microphone can extend through the cabinet. The mic is supported using a single strand color insulated copper wire. The mic electrical cable has a negative shield side to reduce interference. The microphone has a foam covering fabricated from a discarded headset. The wire support is bendable for best positioning.

Microphone Modifications
One improvement, since moving very close to the mic produces a much better signal and greater clarity, is a funnel that can direct the sound into the mic. This may be a great improvement and needs further testing. It may resemble a miniature old fashioned Thomas Edison "Gramophone." The cone can be fabricated from paper, cardboard or plastic from a bottle.

Microphone Measurement
The microphone resistance is measured at 1.37 ohms.

Microphone Impedance
http://www.edaboard.com/thread217554.html

http://www.gearslutz.com/board/geekslutz-forum/764918-what-should-follow-electret-mic-capsule.html 

Definitions
SPL - Sound Pressure Level

Microphone - Receiver that converts sound energy to electrical energy. Also described as a sound sensor.

Condenser - Another term used for a capacitor: two plates separated by a fixed distance capable of storing an electric charge.

Electret - An electrical property which describes the capability to retain electrical charges.

Pascal (Pa); bar (1Pa = 10 u bars) - Unit of pressure. For microphone applications, this unit refers to 
the pressure of sound on a microphone.

Links
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-controls.html

http://en.wikipedia.org/wiki/Electret_microphone

FM Radio Station Part 5 Index
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-part-5-index.html

FM Radio Station Mute Function Part 14

Radio Station mute function schematic

FM RADIO STATION MUTE FUNCTION PART 14

This circuit shows details for adding a mute function to the FM radio station. A switch will mute the microphone. When muted, the LED will stay lit.


Microphone Mute Function with LED monitor
When the DPDT switch is in a normalized position, the electret microphone is active, the LED is not connected, and broadcast takes place. When switched, the microphone cuts out, resistor R2 is connected to replace the microphone, and the LED lights. A carrier signal continues to broadcast but there is no sound. The LED is on a separate circuit and does not interfere with the microphone. The microphone resistance is measured at 1.37 ohms (when not in the circuit).

Note: On the schematic, replace the text SPDT with DPDT.

http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-controls.html

FM Radio Station Part 5 Index
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-part-5-index.html 

FM Radio Station Power Monitor Part 13

Radio switch schematic

FM RADIO STATION POWER MONITOR PART 13

Follow the schematic diagram to wire in a power switch and a red LED power-on monitor light.

Guide

The switch turns the radio radio station transmitter on and off. When on, the red LED will remain lit. The LED monitor light does not interfere with the radio station transmitter. This is the first modification add-on to the radio station.

Parts required, 1 LED, 1 resistor, 1 SPST or SPDT (for a future add on) toggle switch. Use the LED wiring guide pictorial and schematic to determine proper LED polarity.

Testing the LED power on/off indicator circuit. The resistor value of 820 ohms was determined with the use of a resistor ohm substitution box.

The guide shows a "looking down view" from above the LED. Shown in the schematic is a SPST switch. The actual radio transmitter will have a SPDT switch.

The 3mm red LED costs NT$1 each (US$.033 each) in a package of 100. The SPDT toggle switch SW1 is priced at NT$18 (US$.60). The resistor R1 is 820 ohm or the next larger resistance.

http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-controls.html

FM Radio Station Part 5 Index
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-part-5-index.html 

FM Radio Station Power Part 12

FM RADIO STATION POWER PART 12

Online mW to W Converter
http://www.rapidtables.com/convert/power/mW_to_Watt.htm

The FM radio station at 100 mW is only .1 watt which is a mere whisper of more powerful radio stations. (1 Watt = 1000 mW)

Relative Power
Measuring the voltage at the antenna can determine the relative power measurement which is useful for tuning, i.e. to a minimal or maximum value. 

Measuring Power
http://www.zen22142.zen.co.uk/Circuits/Testgear/rfprobe.htm

http://preciserf.com/wp-content/uploads/2012/04/Appnote-4-Power-tests1.pdf 

From Code of Federal Regulations Telecommunications 47
Part 80 to End, FCC 80.259
"(c) A reserve transmitter must be equipped to measure antenna current. (d) The antenna power must be determined at the operating carrier frequency by the product of the antenna resistance and the square of the average antenna current both measured at the same point in the antenna circuit at approximately ground potential."

How to Measure Amps or Watts With a Multimeter
Measuring Amps
Step 1: Select the "Current" setting on the main dial of the multimeter. Choose a current range high enough for the circuit being tested. For example, if the circuit has a current that you estimate to be around five amps, select the "10 amp" setting instead of the "1 amp" option. Choosing a setting that is too low can overload the multimeter.

Step 2: Insert the leads into the multimeter connections labeled "current." Typically, the black lead should be connected to the "common" port, while the red lead is connected to a port that matches the selected current range. This arrangement varies, depending on the unit. Consult the multimeter labels carefully to confirm that the configuration is correct for measuring current.

Step 3: Place the multimeter leads into the circuit using a series configuration. The electricity must be redirected to flow completely through the multimeter to obtain an accurate reading. Current should usually move into the red lead and exit the black lead.

Step 4: Read the amount of amperage displayed on the multimeter. Remember to consider this number in the context of the selected current range. For example, the number "10.00" may indicate 10 amps on one setting but only 0.01 amps if the multimeter is set to the smaller "milliamps" range.

Measuring Watts
Step 1: Choose the "Voltage" setting on the multimeter dial. As you did when measuring the current, ensure that the appropriate voltage range is selected. It is usually a good idea to select the highest possible voltage range to prevent an overload.

Step 2: Configure the multimeter leads into the ports marked for "voltage." The black lead can usually remain in the "common" position. Move the red lead to the port labeled for the voltage range being tested.

Step 3: Connect the leads to the circuit in a parallel arrangement. The black lead should link to a negative or grounded point, while the red lead should be touched to a point of the circuit you wish to measure. Unlike a current measurement, a voltage test does not need to be completely redirected through the multimeter.

Step 4: Read the number on the multimeter display. As with current, remember to consider the context of the multimeter range setting.

Step 5: Multiply the amount of current and the amount of voltage in a circuit to determine the watts. For example, a motor circuit that uses 5 amps and 12 volts has 60 watts of power.

A SIMPLE POWER DETERMINATION
Use several incrementing known wattage light bulbs as a test to verify basic power operation of the transmitter. The lamp will present a load to the transmitter that's similar to an antenna. This test may provide a visual indication of the power output from the transmitter, and verify operation of the antenna coupler. Use grain of wheat bulbs for milliwatt ratings.

POWER FORMULA
P=EI, P=(I^2)R where E is voltage in volts and I is current in amps

ANTENNA
The antenna is a small circular loop with a 1.75-inch diameter. It's measurement of resistance for the tiny loop antenna is 0 ohms on every scale from 2K to 20M. The multi-strand antenna wire is a total of 6-inches long. This indicates that power output readings and measurements can be made at the antenna coupler with no antenna needed. The coupler is where the antenna attaches to the board.

The next step is to unravel a length of wire equal to a fundamental size of the wavelength and measure its resistance. If the value is still 0, increase the fundamental, from 1/32th wavelength to 1/16th, then repeat again if the wire still has zero resistance. At 1/8th, the antenna may be too long.

FM Radio Station Part 5 Index
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-part-5-index.html

FM Radio Station Name Part 11

FM RADIO STATION NAME PART 11
Radio station naming conventions and ideas

Whisper Radio
To hear a whisper you need to shut out the noise of the world…

Similar terms: hush

FM Radio Station Part 5 Index
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-part-5-index.html

FM Radio Station QSL Card Part 10

FM RADIO STATION QSL CARD PART 10
Ideas for the design of a radio station QSL card to confirm reception. The QSL card is a special card sent out to acknowledge the reception of a radio station.

* Country Map
* Radio Station Name
* Radio Station Logo
* Radio Station Transmitter Frequency
* Radio Station Transmitter Power
* Radio Station Photo, Equipment, Room, Antenna

* Blank - Name
* Blank - Time, day, month, year
* Blank - Signal strength
* Blank - General location of receiver
* Blank - Receiver Model

Tips for Printing a QSL Card
Use 110 pound or heavier paper for printing
The card should fit into an evelope

LINKS
Part 1
FM Radio Station Announcement
http://humanoidolabs.blogspot.tw/2013/12/big-brain-radio-station.html

Part 2
FM Radio Station Assembly
http://humanoidolabs.blogspot.tw/2013/12/radio-station-part-2.html

Part 3
FM Radio Station Assembly & Tips
http://humanoidolabs.blogspot.tw/2013/12/radio-station-part-3.html

Part 4
FM Radio Station Broadcasting Into Space
http://humanoidolabs.blogspot.tw/2013/12/radio-station-part-4.html

Part 5
FM Radio Station Index
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-part-5-index.html

Part 6
FM Radio Station Programming
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-programming-part-6.html
 
Part 7
FM Radio Station Testing
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-testing-part-7.html

Part 8
FM Radio Station Broadcast Script
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-broadcast-script-part-8.html

Part 9
FM Radio Station Controls 
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-controls.html
 
Part 10
FM Radio Station QSL Card
http://humanoidolabs.blogspot.tw/2013/12/fm-radio-station-qsl-card-part-9.html