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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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43
votes
8answers
10k 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 ...
22
votes
1answer
2k views

Optical audio transmitter can't handle speech

This is a question relating to my project on an optical audio transmitter. I wired up a very simple device in which I use an audio signal transformer (EI14) to modulate the intensity of a laser beam (...
18
votes
2answers
7k views

Can I break a radio tranceiving device by operating it with no antenna connected?

People tell me I shall not use my CB-radio station without an antenna connected or it will result in damage of the device. Is this true and why is this?
16
votes
10answers
5k views

Schematics for a simple radio transmitter that can be built only with passive components?

Fantasized in some of the survivalist, post-catastrophic novels, movies or docudramas is the radio built only with handcrafted or scraped components. Beyond the popular appeal of this stories, I ...
14
votes
3answers
4k views

How do two UARTS know which baud rate to use?

I am reading about the standard protocol for UART and I think that if the receiving UART does not have any idea on what baud rate the data was transmitted, there would be lots of problems. If the ...
13
votes
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 ...
12
votes
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 ...
11
votes
6answers
33k views

ultra low power mini wireless transmitter / receiver?

I'm looking for suggestions for a wireless transmitter & receiver combination. I'm basically just trying to bridge several buttons over a wireless signal(s) (i.e. send a 1 bit signal) in as small ...
7
votes
7answers
3k views

Measuring direction of object (or angle of signal origin)

I am interested in somehow tracking the "compass" direction of a moving object from a reference-station -- in other words, something similar to submarine sonar systems (although I'm unsure how those ...
6
votes
2answers
10k views

Any wireless technology to find the distance between transmitter and receiver

I have a static transmitter and a mobile receiver. Is there any wireless technology to find the distance between the two in real time. Apart from using gps!
6
votes
4answers
392 views

Digital Compass identifying direction of travel for use with trains

I work in a control center for a train company in the UK. Our trains work in either direction but only one end has first class carriages. Because trains on our network reverse quite a lot it is ...
6
votes
2answers
325 views

Tube transmitter tuning

I am trying to tune/tweak/repair this transmitter for a friend of mine. It is oscillating, and it has rf power on the antenna, but it just doesn't seem as "strong" as it should be. The diagram says ...
6
votes
2answers
6k views

What is the advantage of differential Manchester

I can see the advantage of Manchester code over NRZ: you get clock and data in one signal combined. But what does differential Manchester add to that?
5
votes
5answers
452 views

modem free high base AM data transfer possible?

not a very experienced EE, but I was thinking about a system for high speed data transfer, and it is fairly simple conceptually, so I imagine that there must be serious flaws with the method, because ...
5
votes
3answers
343 views

Strange-looking FM transmitter circuit

I found this simple FM transmitter circuit: I built it an it works rather nicely. There are many simple FM transmitter circuits on Google, most of which look basically like this: These work by ...
5
votes
3answers
5k views

Does an RF receiver constantly consume power?

I'm building a battery operated robotic arm and would like to use a cheap, short distance RF transmitter/receiver kit to trigger it. However I would like to know whether the receiver will constantly ...
5
votes
1answer
4k views

FM Transmitter Modulation

I am designing an FM transmitter as a learning experience and for fun, but I am having some difficulty with FM modulation. I am using a VCO with a Colpitts topology and common emitter configuration. ...
5
votes
1answer
2k views

A complete Radio electronics guide

I want to learn all the basics about making a simple radio project. The project is simple... One transmitting device (which only sends out analog signals of some decent frequency.. say 50MHz) and one ...
5
votes
2answers
470 views

Need suggestion in choosing an effective wireless Transmitter and Receiver

My requirement is to transmit a binary form of data from one Road Junction to another road junction which is around 4 to 5 km away. I am going to get the traffic information from each road in the ...
5
votes
2answers
319 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 ...
5
votes
3answers
5k views

How to build cheap radio propagation beacon?

I want to build a Radio Propagation Beacon but I would like to find an integrated circuit that does most or all of the work of the transmitter. Transmit to 28Mhz (Ham 10-meter band) Allow me to feed ...
4
votes
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 ...
4
votes
1answer
2k views

Data over a 5V DC power connector

I am looking for a simple way to encode some data over a dc power line. (Probably using a very low cost IC) In my design, I have a port that provides 5V, 200mA for connecting some device, but now I ...
4
votes
3answers
343 views

How can I reproduce ambient EM fields inside a Faraday enclosure?

I am part of a research team looking at the possible effects of EM fields on psychological function. The experiment calls for participants to perform a series of tests while inside a Faraday tent that ...
4
votes
1answer
1k views

Can someone break down how this receiver works?

I'm having difficulty understand how this receiver works due to its size. It was taken from this site: http://jap.hu/electronic/rf.html. It is on top labled toy car receiver. The toy car transmitter ...
4
votes
2answers
913 views

Can I use a DAC to tune a VCO?

I found some FM transmitter circuits with the MAX2606 VCO. Example: Can I replace R1 with the DAC output from an AVR microcontroller? Or can I connect the DAC directly to Pin 3 of the MAX2606?
4
votes
1answer
2k views

How does a cube sat communicate with ground station with a 1w antenna

I heard that cubesat signals can be received with a hand held radio. Its confusing me that how a 1 metre antenna radiating 1watt energy can simply be received using hand held radios. I am designing a ...
4
votes
2answers
3k views

Wireless transmission/reception through 100 feet (30m), including concrete wall

I have an electrical engineering degree, but little experience in building wireless equipment. I need to transmit a signal through about 100 feet of distance, including a concrete wall. I need ...
4
votes
2answers
1k views

Difference between ultrasonic transmitter sensor and ultrasonic receiver sensor?

What is the difference between ultrasonic transmitter sensor and ultrasonic receiver sensor? Can an ultrasonic receiver sensor be used as an ultrasonic transmitter sensor or vice versa?
4
votes
1answer
1k views

FM Transmitter Circuit

I'm trying to make a FM transmitter work properly. I built the following circuit : I can synchronize with 94.8Mhz channel on any FM radio, I know that because the original sound from that radio is ...
4
votes
1answer
77 views

can I use a choke 150uH inductor for my AM transmitter circuit?

I am trying to develop an AM transmitter but I am having problems with getting a variable capacitor and inductor (for the rf circuit) in my location. I was able to find a choke coil with an inductance ...
4
votes
1answer
893 views

How do I determine the proper FM transmitter strength?

I want to build an FM transmitter that will transmit (on an unused frequency) from my laptop (near my video projector) to my receiver (about 20' away on the other side of the room). Then, I thought ...
3
votes
1answer
1k views

How does this FM transmitter work?

I'm an electronics student and I have been trying to understand this FM transmitter diagram (taken from electronicshub.org) for a long time. I had put efforts to learn it by surfing the web but parts ...
3
votes
2answers
9k views

Why did my FM transmitter mysteriously die?

I made a little FM transmitter project a few months ago. I used an Arduino, a litle 4-digit serial LED display, a couple of buttons and an FM transmitter component with breakout board I had this put ...
3
votes
3answers
1k views

Why do receivers have a choke but transmitters don't?

Here's a receiver I found on the web: And here's a transmitter: [ Why do receivers have an inductor specifically designated as a choke (RFC) in their circuits but transmitters don't?
3
votes
3answers
3k views

Changing frequency on RF Link

I am using these RF link modules for a project since I need a cheap, small, and simple wireless link between two microcontrollers. The data being sent is a single integer and can be spam sent to ...
3
votes
2answers
636 views

Is it possible to make a coil-less simple Shortwave Receiver

I am really a newbie here in Electronics and I'm into it as a hobby/passtime. I was going through this simple coil-less Shortwave Transmitter circuit on a blog. Q1 – BC548, X1 – 10.7 MHz ceramic ...
3
votes
2answers
10k views

How to find out what radio frequency is being emitted?

Let's say I have something akin to a garage door clicker. How can I discover the frequency and message it sends with no other information on the device? I want to decode this to the electrical ...
3
votes
2answers
709 views

Determining type of modulation

The circuit below is a radio transmitter circuit of a typical RC car. The circuit makes use of IC TX2 encoder. The output of IC ("SO" pin) is a series of pulses at low speed (84 Hz). This signal will ...
3
votes
3answers
131 views

Improving the quality of an optical audio transmitter

I wired up a very simple device in which I use an audio signal transformer (EI14) to modulate the intensity of a laser beam (a cheap 650nm, 5mW diode) according to the audio output of my phone. The ...
3
votes
1answer
1k views

Advantages of Heterodyne vs Homodyne

What are the main advantages from a theorical point of view of a Heterodyne transmitter versus a Homodyne Transmitter? I've seen the main difference is the VCO or PLL connected to the Mixer after the ...
3
votes
1answer
278 views

A question about resonance and crystal radio?

This is a circuit of crystal radio transmitter. I've tested it, and it works properly. but I can't understand everything in this circuit... L1 and C5 make resonance frequency, Would you tell me if ...
3
votes
2answers
811 views

Designing a Morse code transmit/receive shoe

Thank you for considering my general question, which I assure you is serious! I want to build -- or have built -- a magnificent shoe that can convert taps (front of the shoe) into Morse code and ...
3
votes
1answer
2k views

arduino rf communication: beginner

I would like to implement a home-automation system on my arduino. For this project I would like to communicate with the different devices by radio frequency. So that would be different 433 mhz ...
3
votes
1answer
59 views

Can long-range radio waves from an RTV tower penetrate thin plastic composite material next to its source?

We are currently developing a conceptual design for the renovation of Croatia's main RTV tower located on 1033 meter tall peak Sljeme at the Medvednica mountain north of Zagreb. The idea is to ...
3
votes
1answer
350 views

Switching Mixers for LO frequency= 4.25Ghz

I want to upconvert a square pulse of 250 Mhz bandwidth(250Mhz is the value of the first zero of the sinc ) to a center frequency of 4.25 Ghz , so that the spread becomes from 4Ghz to 4.5 Ghz. ...
3
votes
0answers
50 views

Microphonic SAW transmitter?

I built this very simple SAW transmitter, with a simple "spring" antenna for the right frequency. To test it, I tuned a portable receiver to around 433.92Mhz and fine tuned it until I heard silence. ...
3
votes
2answers
414 views

Product design requirements to pass FCC regulations

I've been spending a lot of time looking at 47 CRF 15, and specifically .231, and I don't understand how these limits are possible for many products. I'm designing a remote control for a product that ...
2
votes
2answers
14k views

Is it possible to use 2-way walkie talkie to locate position?

Basically, given no GPS is allowed, can we use walkie talkie to locate the position of a car / a person? I am assuming the walkie talkie is using radio, not GPS-based. What equipments will be ...
2
votes
2answers
340 views

Is it possible to broadcast FM radio up to 500 metres? [closed]

I'm buying FM transmitter 0.2 watt at Lazada to broadcast for my village community at my area. Not a normal small FM transmitter for car or portable low watt (about 10mW-100mW) which broadcast up to ...