Can it be easily done? I don't know how those sockets work, but here's my issue...
I have a pair of panel speakers in my shower which were driven by a built- in radio/amp which has long since expired. My Cunning Plan is now to replace this unit with a bluetooth receiver/amp, which will then receive content from my phone or preferably, from the radio in the bedroom, for which I've just ordered a little bluetooth transmitter which plugs into its headphone socket. That should work fine, except that I'll obviously need to unplug the transmitter every time I want to listen to the radio in the bedroom, as the 3.5mm headphone jackplug mutes the radio speakers.
Is there a way of easily preventing the muting, without trashing the radio? I have no use for headphones as such at all.
Normally a mechanical component of the switch. Can you get access to the inside of the radio and adjust the contacts so that insertion of the plug does not break the circuit to the internal speaker.
That very much depends on the radio. If its old school then there is a mechanical switch operated by the plug, which may or may not be easy to bypass if you go inside with a good soldering iron and a short bit of wire, or if its software based then I suspect if its not in the menu, you are stuffed. Even if its hardware, it may well be that the speaker load will be such that the actual voltage when its connected might well be too low for the blue tooth dongle. You really need a radio with a line out socket. The old Pure models had this and in that case the line out jack was fixed and the volume still controlled the speaker. This idea of using the headphone jack will always be variable output even if you do bypass the switch on the socket.
Also, be wary of overloading the device (eg Bluetooth transmitter) if you set the radio's volume too high. I use FM headphones with my PC and if I set the PC volume (software slider on Sound icon) too high, the headphone sound is distorted, even if I turn the headphone volume down. I tend to use the lowest PC volume and the highest headphone volume - empirically that gives best results.
That is a hand wired mono jack. The radio might have the jack mounted on the printed circuit board. Also, if it is capable of producing stereo it will have a third contact - a ring between the earth sleeve and the tip. This will also have a switched contact.
It will be very important to isentify the correct contacts to short on the PCB as getting it wrong and connecting an output to ground can destroy the audio amplifier.
There will be pads on the PCB on both sides of the jack - two rows of two, if mono, two rows of three for stereo.
The pads furthest from the jack's input will be the ones to short ACROSS the jack, not along it!
If it is a stereo jack, the centre contacts on both sides should alse be shorted
However, there can be variations in the connection arrangements, so remember the old maxim: if in doubt, DON'T!
"NY" grunted in news: snipped-for-privacy@brightview.co.uk:
Thanks, everyone. I haven't received my transmitter yet, so at least I'll be wanting to check the system works as envisaged before opening up the radio to mess with the wiring - will post back when I do that!
FWIW I will certainly need to maintain the output as the headphone socket, since the bluetooth receiver / amp has no controls at all, and I will therefore be reliant on the radio knobs to adjust the volume. Thinking about it though, that means that it might be absolutely necessary to have the radio's speakers turned off when I use the Bluetooth transmitter, if it turns out that the volume of the two sets of speakers are wildly mismatched...
Note that the Bluetooth will introduce a significant latency (delay) into reproduction, so you won't want to be within earshot of both the direct and the Bluetooth speakers. Or get an extra Bluetooth speaker for your bedroom and hope they have equal latency.
I'm inclined to think that Bluetooth is significantly deficient as a means for wireless audio - pairing difficulties, lack of range, especially through walls, plus the latency - unfortunately analogue alternatives are rather hard to obtain these days. 863 MHz is available, but only with headphones AFAIK. FM is a possibility, so you can use a normal FM tranny as a speaker, but it's hard to obtain a useable transmitter.
Quite. I never cease to be glad I cable my house for audio when I rewired many many years ago. Means no reason to have out of sync audio in different rooms.
After a number of attempts to build a stable FM modulator during the 60s [1] - all of which proved eminently unstabe (!) I came across this circuit which proved unconditionally stable.
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I built mine on a Printed Circuit board and used a PP3 for power. Just laying on the bench it was so stable that it was unbelievable. Although intended to be connected to a receiver via a cable (it came from a stereo encoder design) there was nothing connected to it - not even a primitive aerial.
Radiation from the coil was sufficient to cover a reasonably large area. Only if you placed a finger within about half an inch from the coil could you detune it.
I built another one that just had a fixed 10pF capacitor in place of the trimmer between collector and emitter of the transistor and that worked fine as well. Tuning is by squeezing or stretching the turns of the coil to alter its length.
You could, of course, build it in a metal tin and fit an aerial socket. The circuit shows all of the earth connections being returned to a common point but on my PCB I simply allowed a generous width for the earth and that worked fine.
If you fancy making your own PCB you could copy my idea. First draw out the layout on a sheet of 0.1" graph paper, keeping the layout as compact as possible. Clean the copper laminate and emporarily stick the paper to it with sellotape then use a centre punch or any sharp point to mark the copper at every connection point.
Draw the track layout using nail varnish - if you can find black or any dense colour, so much the better as it shows up well on the polished copper.
The etchant normally used is ferric chloride but dilute nitric acid might be easier to find
Drill, build and enjoy!
[1] Where I was working we had two radios and a radiogram in, all with intermittent faults on FM. In those days, with only the Light, Home and Third Programmes available, the daytime fare was abusmal: The Morning Service, Mrs Dale's Diary, Womans Hour, Listen with Mother and so on.
After a successful modulator was built we had Radio Caroline on FM - much easier on the easr!
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