Questions on a set of equipment used to generate and transmit electromagnetic waves carrying messages or signals, esp. those of radio or television.

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3answers
103 views

Could transmit/receive turnaround be improved by having a heterodyne receiver switchable between high-side and low-side injection

In some of the small radios I've worked with such as the Nordic Semiconductor 24LE line, there is a significant (100us+) delay between transmitting data and being able to receive a response. By my ...
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2answers
134 views

Questions about FM receivers and transmitters?

I have a test tommorrow on phase lock loops, AM/FM receivers along with several other topics. I need to understand this topic clearly before I take the exam to advance to the next schooling in the ...
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1answer
46 views

How much power does a phone consume each time it ping its SIM's ID to the nearest cell tower? [closed]

I am trying to build a device than can be tracked through the cellular network. Like a phone, for every few second the device will ping its identity to near by cell tower, which will inform the Mobile ...
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2answers
132 views

Understanding a simple crystal oscillator transmitter circuit

I've recently built this circuit: http://makerf.com/posts/mighty_simple_shortwave_transmitter It works on the desired frequency as you can see from this video : ...
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1answer
93 views

Orientation of ultrasonic receiver

I would like to use an ultrasonic transmitter and three receivers to be able to determine the position of the transmitter relative to the receivers. The distances to be measured are around 3-4 ft. I ...
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1answer
38 views

Using HT12E/D with RX/TX 433Mhz modules

i have ht12d and ht12e ic's and rx tx 433Mhz modules. i arranged the ht12e to the output port of Microcontroller and connected the ht12e to transmitter and similarly to the recieving side. is it now ...
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2answers
56 views

Intercom Malfunction [closed]

I'm an electrical engineer, but I didn't pay close enough attention in my Comms Systems class apparently because this baffles me. Hoping someone else has a better guess about what is going on and/or ...
0
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3answers
282 views

How to build a simple LED transmitter and receiver

I'd like the distance to be about 1/10th of a mile; less distance will be fine if that's easier to build. What tools and parts may I need for this? I have plenty of LEDs lying around and I have ...
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2answers
65 views

How to transmit a signal to a reciever over 50 meters?

I'm studying at a technical college in Denmark, and I'm doing an exam project involving emergency calls for elders. I'm currently trying to build a solution, but it involves a transmitter which can ...
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2answers
71 views

Arduino along with radio tx/rx

I'm thinking about a project similar to the home-automation systems etc... Few problems came in the way, The cost of the Arduino radio receivers/transmitters is huge, especially if I need few of ...
0
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1answer
38 views

How to adjust or obtain different IR Transmitter's distances?

I would like to recreate a infrared concept used by in the vacuum cleaning robot's charging station. I would like to use 3 infrared transmitters all in same wave length and transmit a synchronized ...
0
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2answers
118 views

How to remove the static sound in an fm transmitter

Hi I have a school project and I used the schematics from this website for our FM transmitter. Its actually working but its hard to recognize the music being played because of the static, also does ...
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0answers
139 views

Is wireless power transfer by induction at 60Hz possible, or does the frequency need to be changed?

I want to build a wireless power transmitter that works over a very short distance. Can I use my line voltage(120V at 60Hz) through the primary coil to induce voltage into a secondary coil about 1/4" ...
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1answer
45 views

Use 555 Timer Voltage Doubler to Increase Range of Transmission

I have seen a number of 555 timer voltage doubler circuits. I am building a fm radio transmitter like this one: I understand that the higher voltage the farther the transmission range. Would this ...
0
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1answer
46 views

How do cell phones modulate transmission data

Is it digital, as in the the phone transmitter is turned on and off corresponding to the bits, or is it FM or AM? at what frequency? and how is it that they can transmit what appears to be over large ...
0
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1answer
28 views

Looking for a LED transmitter/receiver package(or group of components)

I am trying to design a system that utilizes 355nm and 370nm LEDs. I want to keep their intensity stabilized at a certain value, so I want to create a feedback loop. I am using these LEDs as ...
0
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1answer
85 views

Use Potentiometer to change frequency in FM Radio Transmitter

I know that in most circuits you use a tank circuit consisting of an inductor and variable capacitor in parallel to generate different frequencies like this one. However since most cheap trimmer caps ...
0
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1answer
37 views

Use Preformed inductor instead of coil for FM Transmitter

I want to build this transmitter: The inductor in the schematic says 0.1uh so I figured I could get some of these and use them instead of making my own like it describes in the picture. I would be ...
0
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1answer
99 views

2n3904 vs. Pn2222A for FM Radio Transmitters

My question is which is better for transmitting an audio signal on the common 88 - 108 fm band: the common 2n3904 NPN transistor or the PN2222A NPN or are they interchangeable. I have seen a lot of ...
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1answer
84 views

555 timer as FM transmitter vs. Tank Circuit

This site seems to suggest the use of the 555 timer in astable mode to generate frequency modulation from a source. The typical transmitter uses a tank circuit with an inductor and trimmer capacitor ...
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2answers
176 views

What technique can I use to focus a Bluetooth 4 transmission (or at least shield it)?

I'm actually trying to focus an iBeacon that uses Bluetooth 4.0 LE. These transmit in the ISM band from 2.4 to 2.485 GHz. Normally these things radiate in a spherical, or half spherical pattern, but ...
1
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1answer
72 views

Transmit electrical signal across human body [closed]

Is it possible to transmit and receive an electrical signal SAFELY using the human body as a medium? For example, I would have a transmitter of some sorts in my left hand, and a receiver in my right. ...
0
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1answer
59 views

Timed Infrared or Infrared PWM Signals

We are trying to have a moving IR receiver pickup a specific IR-led for a range of IR-LEDs. The options we're looking at : Send and unique pwm signal from each different led, the moving object ...
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0answers
45 views

Transmitting data over Long range ,using a Low Power Circuit

I Have Been Designing a BOT That Would Travel Along the Pipeline And Detect Leakage Using Ultrasound Efficiently,And Locate The Position of Leakage Using A GPS MODULE using the Arduino,I have make it ...
1
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1answer
99 views

Boost a weak AM transmitter

I've made this simple AM transmitter: http://makerf.com/posts/fun_with_crystal_oscillators_part_3 The author of this circuit, claims that would be possible to extend the range of this transmitter ...
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0answers
57 views

How to convert laptop to charge wireless

I am wanting to charge my laptop using Qi wireless charging transmitters and receivers. Setup: The laptop battery is a Li-ion belonging to a Sony Vaio Flip 15A (output: 15v 3.17 Amp, input: 19.5v ...
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0answers
19 views

T/R switch for single element material thickness testing (-200V pulses)

Our non destructing ultrasonic inspection design now has two crystals, one for transmitting and one for receiving. We would like to have only one crystal for transmitting and receiving. This is common ...
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1answer
215 views

GPS SOS Signal Device

Is there a way to send GPS coordinates from one device to another, without the use of any kind of cell service? What I'm attempting to design is a device that connect to a motorcycles' tip-over ...
-1
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1answer
134 views

RF - separate transmitter and receiver antennas for half duplex

i was wondering why is it for just half duplex systems, don't we have a dedicated transceiver and a dedicated transmitter antenna. ok, just hear me out... assuming we are using grounded monopoles, ...
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0answers
38 views

One Transmitter for multiple recievers

I need to track case pans at work, I would like to do so by using cheap 433Mhz receivers. My problem is we have up to six hundred case pans in the building at any given time. Will I be able to use one ...
1
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0answers
59 views

Best transmitter and receiver for the job? [closed]

I am very much an amateur when it comes to this just to warn you. I am trying to build a device which will on the press of a button has a transmitter send a 6 digit code to a receiver, which will ...
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1answer
1k views

Generating Rolling Code with Arduino for RF Switch

I am working home automation using Arduino and TX/RX module. From various sources I learned that Rolling Code based RF Switches are having better security. I have following queries How suitable it ...
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0answers
25 views

High level sensor protocols

We are developing a sensor gateway for industrial usage (a kind of internet of things transmitter). The type of sensors are slow frequency sensors with measurement intervals above 1 second (e.g. for ...
1
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2answers
49 views

What are the trade-offs of transmission bands?

If I were designing an RF circuit how do I determine what band the circuit should operate on? What are the trade offs? and why is the higher the frequency the lower range? It is quite un-intuitive for ...
10
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2answers
608 views

How does the plastic-tube inductor in this wireless transmitter work?

This single layer PCB (solder side shown here) is from an old fan remote: The inductor in the plastic tube is not connected physically to any components; however, the two loops of wire surrounding ...
0
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2answers
68 views

Peak-to-peak voltage of WRL-10534?

I'm experimenting with the 434 MHz RF Link transmitter (WRL-10534) from SparkFun. I'd like to determine the peak-to-peak voltage of the RF output, but I don't have access to an oscilloscope that can ...
1
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1answer
74 views

Wireless transmission power for multiple receivers

I have just started learning about wireless systems and for some reason I'm hung up on what I feel is a fundamental idea. Consider some transmitter-receiver pair with isotropic antennas. The receiver ...
0
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1answer
40 views

Replace LED by a Trasmitter

I need a wireless switch with capability to report current state, so I would like to modify a wireless switche like this, by replacing a current state LED by a trasmitter to get the state of current ...
1
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2answers
262 views

square wave carrier signal

I am having some trouble to put things together into one picture. Can a modulated carrier wave be a square wave? If yes then How? Because at resonant frequency at the transmitter, the current ...
1
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2answers
152 views

How would I measure distance with a transmitter/receiver pair?

I am looking to build a a device that can transmit/receive its distance from another device, with the other device doing the same up to 50 meters. Will using a fm transmitter and receiver with a ...
10
votes
4answers
556 views

How is it possible to have a 5W transmitter driving 50 ohms with a 12V supply?

So let's say you have a circuit, which generates a carrier wave at some frequency (let's say 27MHz) and it's connected to a 50 ohm dummy load (which I gather is equivalent to an antenna for circuit ...
1
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2answers
71 views

Distinguish between two ultrasonic transmitters

I want to have two ultrasonic transmitters emit signals to three receivers for measuring distances and relative position of the transmitters to the receivers. The distance between the transmitters is ...
-1
votes
1answer
501 views

What is the best and simple circuit diagram for a radio receiver to receive radio waves in Citizen's Band [closed]

I am building a two way radio system using the citizen's band in India. The transmitter is using a 555 timer IC clocked at a frequency between 26.957-27.383MHz to transmit AM waves. Can you please ...
0
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3answers
183 views

What's the relationship between samples and bits?

I was talking to a friend today that I have a transmitter which is capable of sending 128 samples/second. Note that each sample is a voltage level represented by a floating point decimal. He then ...
1
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0answers
332 views

Datasheet for Keyes IR Transmitter (KY-005) wanted

Can someone help me find the datasheet for the Keyes IR Transmitter (KY-005)? I know how the pins work, I just need to figure out its voltage drop and how much current should go through it. Thanks! ...
0
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0answers
42 views

Is this an antenna or an inductor or both? And does the wire length/core diameter matter?

I have a small transmitter, and attached to it is this device: However, one of the wires attaching the circuit board to to circular red device is broken. I figured that since I have it all taken ...
2
votes
1answer
662 views

How do I sniff this RF Transmitter Gate Opener Circuit?

What piece of hardware am I looking for to observe the transmitted radio signal? Would an oscilloscope come in handy here? is this a 2-channel RF remote, a 3channel RF remote, or something else? My ...
0
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2answers
332 views

2.4 GHz versus 434 MHz transceiver for home automation

I am working on a project that uses an Arduino Uno R3 and will have one receiver and one transmitter. I'm going to use this for home automation within my home in India. I want to know which ...
1
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1answer
133 views

Connecting dipole antenna for transmission

I have a small FM transmitter on a breakout, the antenna is a single connection. It came with a thin blue wire for this purpose; below it spirals up and out the top of the photo. This works fine ...
0
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1answer
705 views

Creating a home made ultrasound transducer

I don't know how ultrasound transducers (transmitters) are made, is it possible to create a home made ultrasound transmitter with a custom specific range 1MHz or more? If it is not, would a 3D ...