Kitchen Radio/CD Player

[Electrone]

I have been looking for a kitchen under cabinet radio/cd player to replace one we have had for a few years which developed a problem with the cd player which i couldn't fix and and so decided to scrap it. There seem to be very few available. I bought one, an AEG, through Amazon which came from Germany. This made a ticking sound as the CD player was operating which I wasn't happy with so I sent it back for replacement. The display on the replacement radio went blank after approx 24Hrs on standby so I returned it for refund.

I am considering adapting a car radio to mount under a cabinet with two small speakers. It will never be played at loud volume settings so I presume a switched mode power supply capable of delivering about 3 amps should suffice, (I don't want a conventional heavy transformer/rectifier type) provided it doesn't inject audible noise into the radio.. All modern car radios have a low current supply which is permanently connected to the car battery to maintain the station preset memories. I assume this supply is only milliamps so, to maintain the station memories if the radio is disconnected from the mains, I propose making up a 12v lithium battery pack for this supply. I hope this should last many months. I considered using NimH cells kept charged by the main power supply but dismissed this idea on the grounds of cost and extra complication.

Before I embark on this project and start spending money I would welcome comments from other Forum members in case there are likely to be any problems I haven't considered

Michael

[Nickthedentist]

Hi Michael,

I use such a set-up at work, except that mine takes cassettes(!) as a Blaupunkt-made VW Gamma V from about 2000 was all I had lying around.

It's mounted under a worktop, using a mounting cradle which you used to be able to buy in Halfords etc.

Power is from a 5A SMPS rescued from an ancient (1990-ish?) laptop. The permanent, switched and illumination 12V inputs are all linked together, and the mains left permanently on. It's given no trouble in the 5 years or so it's been installed. If there's a power cut or the RCD trips, I need to re-enter the security code, but the station presets are non-volatile, as I think many are these days.

Aerial is just a few feet of flex nailed to the underside of the worktop. Speakers are 1980s Pioneers connected to the front outputs, plus an old ex-surround sound subwoofer connected to one of the rear outputs, the fader control being used to choose how bassy I want it to sound.

Nick.

[terrybull]

Not only will the power need to be permanently on for the pre sets but many modern radios will need a security code to be entered every time the power is disconnected.

[Electrone]

Thanks, Nick, for your comments It's nice to know someone else has a similar set up and it's very sucessful

Michael

[Paul Stenning]

Depending on the height of the ceiling and cabinets, there may be room for a power supply and even a pair of reasonable speakers on top of the wall cabinets. Power could then perhaps be taking from the cooker hood circuit (if it's accessible up there) so you don't lose a socket.

[Nickthedentist]

Yes, quite. A good use for those excellent-sounding-but-battered speakers most of us have lying around as they'll be all but out of sight (and are likely to get a bit gungey even in the cleanest of kitchens).

This is the kind of mounting arrangement which I was referring to: http://www.ebay.co.uk/itm/CLASSIC-MI...-/111058385292

N.

Originally Posted by Electrone

I propose making up a 12v lithium battery pack for this supply. I hope this should last many months. I considered using NimH cells kept charged by the main power supply but dismissed this idea on the grounds of cost and extra complication.

Although Lithiums are quite simple to implement it takes quite a lot of accurate stuff to stop them failing (blowing up). It would be much cheaper to just leave the power on to the standby line.

[G6Tanuki]

Old car-radio-cassettes were the music-source-of-choice for Welsh village pubs a few decades back; a cheap 3-amp CB-radio power supply works just fine (though many of these were horribly wired with the on/off switch in the negative line).

The "permanent live" feed on a recent-generation car radio/cassette/CD-player only takes a few microamps: a while back I needed to do some fairly-long-duration work on a car whose owner didn't have the 4-digit security-code for their radio/CD so I hooked up a zinc-carbon PP3 to provide juice on the permanent-live, which worked fine for the week or so it took to get the car's gearbox removed/rebuilt/refitted.

[Electrone]

Thanks to everyone who posted advice and suggestions, especially Nick for pointing me in the direction of a suitable mounting tray. I was going to construct one out of wood to hold the radio and speakers, this would save me the bother, only problem is finding somewhere for the speakers as they would have to be separate in our small cluttered kitchen. However I'll get round that problem in due course!

[Electrone]

I have built my kitchen under cabinet Radio /CD Player. The result is shown in the attached pictures. It is based on a Sony Car Radio Model CDX-GT23. I wanted to keep the case as slim as possible whilst using speakers of a size which would give reasonable sound quality. My carpentry skills are fairly basic and I couldn’t think of a method of making attractive speaker grills and getting them right first time and so the speakers face downwards with black circular grilles fitted. There is no space in our small kitchen for separate speakers. The case is constructed in 9mm ply covered with a material called Masterflex with a beech finish which a friend gave me This is like veneer but thicker. Picture 1 shows the completed radio mounted under a cupboard. (It looks bent in the picture I can assure readers it is not!) I think this is a result of cropping the original photograph) Picture 2 shows the interior of the radio. The mains supply is shown on the left. This is a 5 amp switched mode supply giving 12 volts. The backup power supply (to keep the station presets alive if the mains supply is switched off) is shown on the right. The diodes shown in the circuit are mounted on the terminal block at the rear.

The circuit I devised for the power supply is shown in picture 3. Before describing the function of this it is worth considering how the preset station memories are kept alive in a car radio. There are two lines carrying 12 volts, a switched supply on a red coloured wire which is supplied via the ignition switch and a main supply on a yellow wire fed directly from the car battery via a fuse. 12 volts on both lines allows the radio to be switched on at the front panel. When the ignition is switched off, 12 volts disappears from the red line which switches off the main circuits in the radio but the memories are still supplied from the yellow supply keeping them alive.

However when the radio is supplied from a mains power supply the situation is somewhat different

The circuit functions as follows:

The 12 volts from the mains power supply is fed via diode D1 to the yellow feed wire to the radio. The back up supply consists of 7 AA cells giving 10.5 volts at the anode of D2. There is a 0.5 volts drop across D1 giving m 11.5 volts at the cathode of D2 which therefore does not conduct. 12 volts is fed to the red wire of the radio, (this is normally switched by the ignition switch when used in a car. enabling the radio to be switched on at the front panel). If the mains supply is switched off, the 12 volts supplied through D1 disappears and D2 is allowed to conduct feeding 10 volts (0.5 volts drop across D2) to the yellow supply line which keeps the memories alive. D1 isolates the back up supply from the red switching supply line. If D1 was not present, 10 volts would remain on the red supply which would try to keep the radio going (if the mains supply failed whilst it was switched on at the front panel) which would quickly drain the back up battery pack.

The radio has been in use for some three months now with no problems. The mains supply has failed on several occasions, twice when I tripped the property supply whilst working in my workshop and there have been a couple of local supply failures which are fairly common as we are situated in a rural area. The station presets have remained intact. The sound quality from the radio is much better than that produced by the two commercial sets we have had. The Sony has RDS and the front panel clock is radio controlled, two features which are useful.

[Colin Ames]

Nice job!

Colin

[Electrone]

Thanks, Colin!

Michael

[Nickthedentist]

Yes, seconded. A good use of a spare car stereo, of which there are lots around these days.

Your construction looks very neat and workmanlike.

Nick.

[unitaudio]

Beautifully simple and very tidy. And those speakers will be rather better than the ones used in commercially available kitchen radios. A neat unit that could find use in a variety of locations around the house and workshop. Nice work!

Regards,
Paul

[paulsherwin]

If you don't need to play CDs, this is an excellent way of reusing old car radios from the last 30 years. These usually have very good AM and FM sensitivity and quite low current drain unless you really turn them up - in fact a 1A wall wart scavenged from something will usually do the job. You can connect them to a single speaker if you are pushed for space and don't need stereo.

They make good workshop and garage radios too.

I tend to run old bangers and often scrap them rather than selling them on. I usually retain the radios and have about 6 in plastic bags in the garage.

[Nickthedentist]

Snap, Paul! Except I counted eight last time I looked.

You could also build one inside the very bottom section of a wall cupboard for minimal visual impact, with the speakers firing downwards towards the worktop. All you'd need is one of the existing shelves moved down to about 4" from the bottom of the cupboard, and a small rectangle of matching chipboard on which to mount the radio itself.

[Electrone]

Many thanks to all the Forum members who responded with complimentary comments.

Michael