Radio

a capacitor is frequently placed across a 110V line to reduce the noise in radios.what is the smallest voltage such a capacitor should have?

110 VAC is the rms voltage that is an effective equivalent to 110VDC.

The 110 VAC voltage actually gets to a higher peak voltage of

1.414 x 110 = 155.54 volts peak

These higher peak voltages although brief in duration can damage a capacitors dielectric insulation if the peak voltage exceeds the working voltage of the cap

You could also add a safety factor of at least 10%(or more) so a cap rated no less than 175 would be required. Higher voltage rated caps (200v for example) would work and provide an added measure of safety

If I did get into Morse code, I would want to purchase a small, portable radio to send messages. Portability, for me, would be huge if it were possible to find a portable radio.

Also, how small do these radios typically get? Is it possible to get something as small as a walkee-talkee?

Radios which do morse code can be very small! Personally, I built one and put it in an Altoids tin. I probably could have fit it in something smaller even but you can’t beat the price and they’re everywhere. It’s a 30m rock-mite transceiver and transmits half a watt. It was only $29 from smallwonderlabs.com. Another interesting tiny morse transceiver is the ATS-3b, which has a VFO, operates on 6 bands and up to 4 watts and will still fit in an Altoids tin!

cn someone give the whole science behind it? how did they develop it? how did they know they could transfer signals through wires..how did they know to convert signals to transmissions? how do they use satelites and frequency in radios? etc etc…
well the 1st answer doesnt help at all…..

That would take half a day to answer so I will refer you to a couple useful links through wikipedia.

In short, the discovery of electricity led to the study of it for any purpose imaginable from communications to physical therapy to mechanics. The telegraph would transmit electrical pulses (long and short) over a conductive wire and an alphabet of dashes and dots was created to utilize this means of communications.

Radio was discovered by combining electric and magnetic waves of energy to produce an electromagnetic signal that could be tuned to transmit or receive different frequencies.

Telegraph
http://en.wikipedia.org/wiki/Electrical_telegraph

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

P.S. If you really want to learn about the mechanics of radio technology I suggest building one. I made one when I was younger and it was a good experience, but I believe they sell radio building kits now so it shouldn’t be as difficult gathering up all the materials.

I get one heck of an interference on my TV from the local taxis as they use their radios (i live next to a main road).

Pleas help it is driving me NUTS!!!! thanks!
I can actually hear what they say and where they are going whilst the TV goes into white noise.
Thanks for your answers, but i DO use Digital TV, though with an indoor aerial.

Hiya !

One solution would be to use a couple of ferrite rings in your aerial lead – something like these from Maplin Electronics…

http://www.maplin.co.uk/Search.aspx?criteria=ferrite ring&source=15

If you want more details – drop me an email

bought yesterday. Neither will work on batteries. The batteries are brand new and ive tested them with a battery tester and the battery tester is brand new. The batteries are duracell they say 9v2 on the package. The radios say they take one 9v battery. I dont know whats wrong.

The clock should still work on batteries, or maybe the batteries only act as a backup, so that when AC power is restored your clock is still set. Your cd player however will not work simply on a 9v battery.

what are these kinds of radios, perhaps where could I buy one?

THANKS

The units are called "Scanners".
I don’t know where you live but in canada most of the police services have moved from using regular communications systems to a newer system known as "Trunking". You will need to by a trunk tracker scanner in order to listen to what they are saying. These scanners are a bit more difficult to program than the older type because not only do you need to program the frequency the police are using, you also have to program a 4 digit code for the division you want to listen to.
If you live in an area where the cops have not moved to a trunking system then you can use a conventional scanner and listen to cops, fire, ambulance, cordless phone calls,
ham radio, and much more. You can buy either type of these scanners at several electronics stores like "Radio Shack"
"The Source In Canada" as well as stores that sell communications equipment like ham and cb radios. There are several brands but I like the "Uniden" units. You can get handheld battery operated models or one’s for mobile or home base use. If you choose a mobile or home model then there are several types of antennas you can choose from. just make sure you get an antenna that is made for the frequncies you want to listen to. If you want to save some cash you will find tons of scanners for sale on "Ebay".

Take care.

We’re soon going to be combining and we use 2 way radios is it possible, i have the connection to the antenna. so if it would help do I have a coil of wire by the 2 ways antenna? or what?

CB works wit a GP anatenna on a specific frequency (27mhz) Be sure to use the antenna that support the freq you will be using
look on wikipedia

Whenever riding in the car with one of my parents we’re always going from station to station looking for something good. While at home, with tv, we can just search for shows, or go straight to HBO for a movie? How come radios (not just car radios-all of them) haven’t reached that point of interactivity yet- Search for bands, search for songs, or search by genre?

Mainly because radio generated content is not information based. Because you pay for the cable service, more options are given, but as most radio stations do not profit directly from the listeners, they do not have to put as much effort into the process. Also with many different bandwiths and different stations in different areas, a radio with the ability to check for songs/bands/genre would be hard pressed if you were driving and wanted to check for say a Bob Dylan song. The closest you could come right now is satellite radio, they separate the different genres, but you still got to wait for something you like. Sadly, radio is not a true digital signal, it still requires analog signal (radiowaves) to get to your car, keep your ipod handy and filled with songs you like.

I am doing a project for school and I need to know what kind of radios police use in their vehicles and where I can find them priced. Thank you!!!

Usually Motorola radios that are mobile.

They cost around 200-400 brand new.

My dad and I just rented Little Big Planet, and we were wondering what the little radios were in the background. Does anybody know?

they play the music that you hopefully can hear