mp3 FM transmitter c/w USB recharger - would this work?

D

DrMoriarty

Moderator
Messages
5,173
Have lost my trusty Belkin, so was thinking of replacing it with [broken link removed] eBay gizmo. I'm attracted to the idea that it can also be used to recharge the player's batteries via the USB — presumably one of the cables must carry power from the cigarette lighter socket to the battery compartment of the mp3 player, while the other carries the audio signal from the player to the FM transmitter inside the unit.

Can anyone see why I couldn't plug both ends simultaneously into a cheapo USB-type mp3 player — with a rechargeable AAA battery fitted, of course — so that it would trickle-charge the battery and transmit the signal to the car stereo at the same time?

Should I risk $6.91 to find out..? :D
 
For MP3 player / iPod Shuffle charging, just plug the USB cable
Click to expand...
Cheapo USB type MP3 players are unlikely to have a battery charging circuit built in. The USB connection merely delivers power to such a device. It does not obviate the need for a charging circuit being built into the target device. The outside connectors of the 4 in USB are 5V power and ground. There are lots of DIY and commercial USB based charging products out there as you will see if you Google for something like "DIY USB charger". For example I bought a cable for about €2 on eBay (free P&P if I recall correctly) that connects a USB port to my Nokia phone and obviates the need for a separate transformer. However the charging circuit is built into the phone!
 
Ah. I guess you're right, ClubMan — the kids got a few of [broken link removed] (from Argos) as stocking-fillers last Christmas, but I would assume that the USB port is purely for file transfer purposes and that there isn't any charging circuit built into the player.

What do you reckon would be the chances of snipping off that USB plug and replacing it with a standard adaptor jack that would fit the recharger socket on my own 20Gb player? (which obviously does have a built-in charging circuit). I must check the voltage/amp figures...
 
DrMoriarty said:
Ah. I guess you're right, ClubMan — the kids got a few of [broken link removed] (from Argos) as stocking-fillers last Christmas, but I would assume that the USB port is purely for file transfer purposes and that there isn't any charging circuit built into the player.
Click to expand...
The blurb doesn't mention that it uses rechargeables so I would assume that there is no charger built in.
What do you reckon would be the chances of snipping off that USB plug and replacing it with a standard adaptor jack that would fit the recharger socket on my own 20Gb player? (which obviously does have a built-in charging circuit). I must check the voltage/amp figures...
Click to expand...
USB will normally deliver up to 5V and 500mA (?) so I presume cigarette lighter to USB adaptors such as this one will follow suit? Obviously you need to be careful about matching a power source to a device otherwise you could end up with junk.

Two other issues - aren't such FM transmitters technically (!) illegal and bear in mind that some US gadgets have different tuning precision than those normally used here (e.g. the frequency steps used for tuning differ as far as I recall).
 
ClubMan said:
USB will normally deliver up to 5V and 500mA (?) so I presume cigarette lighter to USB adaptors such as this one will follow suit? Obviously you need to be careful about matching a power source to a device otherwise you could end up with junk.
Click to expand...
I hear what you're saying... but presumably the only danger is where the power supply exceeds the rating of the device? (for the purposes of a battery-charging circuit, at least). The mains adaptor/charger for my player has an output rating of +5.0V --- 2.0A 10W, so I would have thought the only problem with the lower output of this yoke would be that the battery would charge more slowly/less completely?

ClubMan said:
Two other issues - aren't such FM transmitters technically (!) illegal and bear in mind that some US gadgets have different tuning precision than those normally used here (e.g. the frequency steps used for tuning differ as far as I recall).
Click to expand...
I'm not even 100% sure about the legality of my kids' mp3 collections..! ;)
 
How long will the MP4 player work off it's own fully recharged battery? Would it be worth looking at the market of MP3 car stereos?
 
You must log in or register to reply here.
Back
Top