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Questions tagged [transmitter]

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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1answer
298 views

Low-Frequency Magnetic Transmitter

I want to design a magnetic transmitter to detect a device which will be underground (1m to 7m) from surface, so I started to look at a solution and I find that a magnetic transmitter will work ...
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2answers
73 views

RFM only works if i touch power supply line

I have a small system with a ATtiny84 and an RFM12B module that transmits data. The thing is it only transmits when i touch both GND and +VCC.. no matter what component it is on. Do i need mere caps ...
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1answer
296 views

Location transmitter [closed]

I want some advices about a radio transmistter,actually this radio trasmitter is more a location transmitter which transmits at about 512Hz.I want to know how could i design a transmiter and a ...
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3answers
2k views

FM transmitter design?

I stumbled across a relatively simple FM radio transmitter online. Credit: makezine.com I wanted to understand how it works (it is called "super simple" on the website), but several hours I have ...
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3answers
3k views

555 AM transmitter

I looked on instructables and I found an interesting(at least for me) AM transmitter made with a 555 timer which acts as the oscillator:http://www.instructables.com/id/555-AM-Transmitter/ Is this ...
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8answers
9k views

Can a radio transmitter somehow detect the number of receivers in its area?

During conversation, a colleague proposed that over-the-air television and radio broadcasters can determine the number of viewers or listeners based on the "load" on their signal. This seems to me ...
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1answer
65 views

ETSI Tx Power standard for short Range Devices. I am Confused

I came across the European Telecommunication Standards Institute (ETSI) standard for non specific Short Range Devices which is documented in EN 300.200 . On page 28 under Section 7.2.3 with Heading ...
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1answer
248 views

How to build a transmitter using a VCO module

this question is the consequence of my previous questions, since I am learning how RF transmitters works. In past I have also built some oscillators (using little transistors and a bunch of components)...
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2answers
1k views

Make an RF transmitter: classic transistor oscillator or VCO module?

This question is about pros and cons of making an RF transmitter (eg in the FM band) in the classical way (eg. with a "transistor based" oscillator circuit, like this one which is very classic and ...
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2answers
116 views

How to solve Power Density Function?

How to solve this problem: A radio receiver needs $$ 1 \textrm{ nW/}\textrm{m}^2 $$ of power density function, how far away from a 1-watt point source will it continue to work?
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3answers
697 views

Transmit power vs. Transmission power, is there a difference?

I was reading a scientific paper, and the authors sometimes use the term "transmit power" and sometimes "transmission power". Is there a difference in terms of correct English usage? Examples: ...
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1answer
564 views

Multichannel RF transmitter design for 315MHz and 433MHz

first time designing RF, so pardon my ignorance. I want to design a ASK/OOK transmitter board operating on both 315Mhz and 433MHz ISM band frequencies. I have a MCU onboard that generates the data to ...
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1answer
95 views

Changing the port values inside the loop (8051)

I am using RX/TX module an ht12d/e for my project. I will make it short, in my program i am making a packet of data and sending it and the receiver is receiving it synchronously. The receiver is set ...
2
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1answer
796 views

Merging right & left signals to mono with op amp?

Sorry for my english i'm a young french. I want to design an audio transmitter to connect my pc to my Hi-Fi without Jack cables. For now i just want to send a mono signal because sending a stereo ...
2
votes
3answers
655 views

What are the basics I need to know to power LEDs with RF at a range of 30 feet?

I would like to light up a path in the woods with hundreds of LEDs using RF. The idea is that I would carry a RF transmitter powerful enough to light LEDs. As I approach the LEDs would get brighter, ...
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2answers
605 views

How do I implement TDMA with basic 433 MHz transmitter receiver pairs?

Is it possible to use TDMA or some kind of time synchronization / pseudo random coding for a number of transmitters so that they can be interfaced with a single master receiver without jamming?
2
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1answer
613 views

Can I transmit in the ISM band without a ham radio license?

I recently purchased a HackRf SDR, which has transmit and recieve capability. I'm debugging a 2.4ghz wireless module, and being able to transmit to it using the hackrf would be very helpful. Since ...
5
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2answers
316 views

Best communication option for multiple arduinos?

My father and I want to develop a cow pedometer to measure a cow's activity. The idea is that if you can measure a cow's activity you can detect when she enters heat. Detecting heat with sensors will ...
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1answer
145 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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1answer
2k 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
111 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
526 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 them,...
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1answer
98 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 ...
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1answer
224 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 ...
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1answer
3k 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 ...
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1answer
1k 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 ...
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1answer
2k 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
1k 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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1answer
513 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
180 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 knows ...
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2answers
7k 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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2answers
3k 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 by ...
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2answers
2k 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
101 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 ...
1
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1answer
269 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 ...
2
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2answers
3k 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 : https://www.youtube.com/watch?v=...
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2answers
6k 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 I'...
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1answer
728 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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4answers
2k 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
79 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 ...
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2answers
874 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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2answers
1k 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 it ...
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2answers
198 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 ...
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1answer
153 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 ...
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1answer
46 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 ...
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2answers
3k 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 ...
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2answers
4k 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 ...
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4answers
3k 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 ...
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2answers
230 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 ...
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1answer
168 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 ...