Car radio/CD player

[colmac]

Hi as per the title, we would like to play CD's on our long summer cruise and would like to fit a car radio/CD player.  We don't have Bluetooth or any other music streaming service. We have a basic electrical set up i.e. 3 leisure batteries, no inverter so would it be possible to do this ? Thank you.

[Jen-in-Wellies]

3 minutes ago, colmac said:

would it be possible to do this ?

Short answer. Yes!

Long answer. A lot of boats have this. This is all late 20th century technology and a lot of boats have had them and many still do. Car radio/cd players are well suited to boats as they are designed for vehicles and have similar electrical systems and electrical noise on those systems.

You will need a suitable sized fuse in the wires connecting it  to your boat electrics.

Do you want the radio to work too? This is the relatively hard bit as a steel boat is good at blocking radio waves. An external aerial is best. Does your boat already have one.

In the 21st century, lots of people now use streaming services, or have ripped their CD's to MP3 and have them on a phone, tablet, or whatever and play them over a bluetooth speaker. This doesn't need any wiring at all, other than some way to recharge the phone and speaker.

Jen

[Flyboy]

1 hour ago, colmac said:

Hi as per the title, we would like to play CD's on our long summer cruise and would like to fit a car radio/CD player.  We don't have Bluetooth or any other music streaming service. We have a basic electrical set up i.e. 3 leisure batteries, no inverter so would it be possible to do this ? Thank you.

No problem at all, you will need an external aerial for best results. If you have a steel boat make sure you have the coaxial aerial cable earthed to it via a small capacitor.

Edited September 30, 2020 by Flyboy

[Tony Brooks]

Yes but the wire then the instructions say goes to the ignition on terminal needs to go to a permanent live unless you want to have to turn the ignition on every time you want to listen. Also the normal positive may well have to go to the battery side of the master switch (fuse close to switch) in case the radio station memory needs a permanent feed.

[Jen-in-Wellies]

1 minute ago, Flyboy said:

No problem at all, you will need an external aerial for best results. If you have a steel boat make sure you have the coaxial aerial cable earthed to it.

Further to that, many car aerials rely on being electrically connected to a steel sheet to work properly. Either a car body, or the steel roof of your boat.

[Tony Brooks]

6 minutes ago, Flyboy said:

No problem at all, you will need an external aerial for best results. If you have a steel boat make sure you have the coaxial aerial cable earthed to it.

Er - not really but the result of doing so may not be as bad as theory suggests. It is supposed to reduce interference.

 

Although the aerial is normally earthed at the mast base it introduces anther negative to hull point so increasing the risk of corrosion. The usual answer given on here is to break the aerial lead outer brade and the reconnect it via a capacitor - I think 47 mf was mentioned. DAB aerials seem to be fine with mag mounting so they are not earthed.

Edited September 30, 2020 by Tony Brooks

[Tracy D'arth]

Be very careful earthing the outer coax of the aerial to the steel hull, if the radio body itself is connected to the battery negative.  This will by pass any isolation switch in the main negative battery connection and can result in the coax setting fire to the boat.

It will also show up as a leak the the hull on an electrical test.

[Flyboy]

3 minutes ago, Tony Brooks said:

Er - not really but the result of doing so may not be as bad as theory suggests.

 

Although the aerial is normally earthed at the mast base it introduces anther negative to hull point so increasing the risk of corrosion. The usual answer given on here is to break the aerial lead outer brade and the reconnect it via a capacitor - I think 47 mf was mentioned. DAB aerials seem to be fine with mag mounting so they are not earthed.

The aerial needs a ground plane so must be earthed at the aerial mount, you will get lots of interference from other electrical equipment in the boat if you don't.  I think you mean a  47pf capacitor.

[WotEver]

12 minutes ago, Flyboy said:

No problem at all, you will need an external aerial for best results. If you have a steel boat make sure you DO NOT have the coaxial aerial cable earthed to it.

Corrected that for you.  Any aerial connection to the earth should be via a small capacitor.

[colmac]

My apologies, we have a very good battery type radio so it was just to play CD's really. Have tried to find a decent battery operated CD player without success. Have researched downloading music etc but are a bit of a pair of Luddites I'm afraid despite our daughters best efforts.

[WotEver]

1 minute ago, Flyboy said:

I think you mean a  47pf capacitor.

We're talking RF, so almost anything will do. 1uF will work too.

[Tony Brooks]

Just now, Flyboy said:

The aerial needs a ground plane so must be earthed at the aerial mount, you will get lots of interference from other electrical equipment in the boat if you don't.  I think you mean a  47pf capacitor.

I happily accept the 47pf because I know I could not remember what the post said. I am not even sure about the importance of a ground plane nowadays. I had my VHF/FM aerial mounted on an earthed small metal bracket screwed on top of the cratch top plank, maybe a total metal area of 2 sq in. and it did not suffer from interference but I well know interference is tricky stuff and involves black magic..

[Tracy D'arth]

The capacitor, just about any value from 0.22uf  to 1uf but with a working voltage over 100v preferably a type Y  should be in between the coax outer braid and the radio to insolate it from the steel hull as far as DC current is concerned.

Edited September 30, 2020 by Tracy D'arth

[Tracy D'arth]

deleted

Edited September 30, 2020 by Tracy D'arth

[Flyboy]

1 hour ago, WotEver said:

We're talking RF, so almost anything will do. 1uF will work too.

47uf won't at VHF.

[WotEver]

20 minutes ago, Flyboy said:

47uf won't at VHF.

Sure it would. We’re talking series here, not parallel. 

[Keeping Up]

24 minutes ago, WotEver said:

Sure it would. We’re talking series here, not parallel. 

No it won't, it will have too much self-inductance and will be a high impedance at VHF (probably at HF too)

[dmr]

Bigger capacitors like 47uF will generally be electrolytics and these have an increasing resistance at higher frequencies, this is why many circuit boards will have a little capacitor in parallel with a big capacitor to do the supply smoothing. I think Tantalums are better but a smaller non electrolytic is probably the way to go.

 

To the OP....

Car CD players were pretty much standard in narrowboats, and likely still are, but if you have a multi-fuel stove don't expect the CD player to last very long, or at least to require frequent cleaning, they don't like the dust. There are advantages to doing things the modern way even though its sad not to need a CD collection. An iPhone to a good bluetooth speaker and a subscription to Spotify is pretty good. With a paid subscription the higher bit rates are available, and some of the newer Bluetooth protocols have very good sound quality. If you want to go really posh then there are some proper hifi quality bluetooth speakers available, like the Ruark MR1, but they do cost.

 

.................Dave

[Tracy D'arth]

48 minutes ago, dmr said:

Bigger capacitors like 47uF will generally be electrolytics and these have an increasing resistance at higher frequencies, this is why many circuit boards will have a little capacitor in parallel with a big capacitor to do the supply smoothing. I think Tantalums are better but a smaller non electrolytic is probably the way to go.

 

To the OP....

Car CD players were pretty much standard in narrowboats, and likely still are, but if you have a multi-fuel stove don't expect the CD player to last very long, or at least to require frequent cleaning, they don't like the dust. There are advantages to doing things the modern way even though its sad not to need a CD collection. An iPhone to a good bluetooth speaker and a subscription to Spotify is pretty good. With a paid subscription the higher bit rates are available, and some of the newer Bluetooth protocols have very good sound quality. If you want to go really posh then there are some proper hifi quality bluetooth speakers available, like the Ruark MR1, but they do cost.

 

.................Dave

Electrolytic are not suitable as isolation capacitors, the have leakage and too high values.  Should be Y type polypropylene or better.

[WotEver]

40 minutes ago, Tracy D'arth said:

Electrolytic are not suitable as isolation capacitors, the have leakage and too high values.  Should be Y type polypropylene or better.

Indeed.  And as a capacitor's reactance is inversely proportional to frequency it can't be 'too big', merely unnecessarily big.

1 hour ago, Keeping Up said:

No it won't, it will have too much self-inductance and will be a high impedance at VHF (probably at HF too)

How does that work then?  Inductance is inversely proportional to frequency.

[Keeping Up]

1 hour ago, WotEver said:

How does that work then?  Inductance is inversely proportional to frequency.

You've lost me there. If you mean that for a capacitor, the impedance is inversely proportional to frequency, then I agree. But for an inductance the impedance is proportional to frequency, and that is what I am talking about. A 47uF capacitor will have a high inductance, particularly as it is almost certainly an electrolytic. In effect it will have a series resonant frequency which is well below VHF, and its impedance will continue to rise with frequency thereafter.

[WotEver]

4 minutes ago, Keeping Up said:

You've lost me there. If you mean that for a capacitor, the impedance is inversely proportional to frequency, then I agree. But for an inductance the impedance is proportional to frequency, and that is what I am talking about. A 47uF capacitor will have a high inductance, particularly as it is almost certainly an electrolytic. In effect it will have a series resonant frequency which is well below VHF, and its impedance will continue to rise with frequency thereafter.

Sorry, I meant reactance, not inductance... d'oh!

[Onewheeler]

2 hours ago, WotEver said:

Indeed.  And as a capacitor's reactance is inversely proportional to frequency it can't be 'too big', merely unnecessarily big.

How does that work then?  Inductance is inversely proportional to frequency.

Read this first. https://passive-components.eu/capacitors-losses-esrimpdfq/

[ditchcrawler]

8 hours ago, Flyboy said:

 If you have a steel boat make sure you have the coaxial aerial cable earthed to it via a small capacitor.

I often wonder how many are

[Flyboy]

2 hours ago, ditchcrawler said:

I often wonder how many are

Very few I reckon.  Years ago when you bought a car it didn't come with radio as standard.  You had to drill a big hole in the front wing, pass the aerial up from underneath making sure you had a good earth onto the metal. If you didn't get a good connection you got loads of interference. Never heard of a fire caused by the coax cable.

Edited September 30, 2020 by Flyboy