Ghost in the machine

[PGH]

I have a clock radio which has served perfectly for the past 30+ years. Yesterday I heard faint voices coming from the bedroom and when I went to investigate realised that I could hear the radio even though it was switched off. The volume was a lot lower than normal and when I switched it on, it returned to normal volume. I unplugged and left it for a while and when I reconnected it, it worked ok for half an hour and then again became audible even though switched off.

Even more mysteriously when I switched on a light to see what I was doing, the phantom broadcast stopped. This happened irrespective of which light in the bedroom I switched on, ie ceiling light or wall light.

While I appreciate that the radio is probably due for retirement, I’m curious about what could be happening and in particular why switching a light on should have an effect. Any suggestions?

PS I don’t really believe in ghosts.

 

[JimB]

Wild guessing time!

First wild guess:
Inside the radio will be some device, typically a transistor which switches the radio on/off.
My best guess is that this transistor has lost gain or has gone "leaky".
When the clock radio was turned off for a while, the iffy transistor cooled down and its characteristics moved back to a better working area.

Second wild guess:
When you turned on the light, a photocell in the clock radio turned up the brightness in the display.
This increase in brightness caused the supply voltage inside the radio to drop slightly, so allowing the iffy transistor to move back to its better working area.

JimB

 

[Nigel Goodwin]

Another wild guess, does the radio have a slide switch, for selecting the more (timer, radio etc.) - these become dirty over time, and a poor contact can cause the radio to operate when it shouldn't.

Try moving the switch back and forth, and see if that helps.

 

[PGH]

JimB and Nigel Goodwin - Thanks for the suggestions all of which sound very plausible. I’d forgotten that the display had an auto dimmer function but can now see that it has so that could be the cause of the mysterious light effect. The radio also has sliding switches for switching on/off, adjusting time, putting into alarm mode etc so I’ll try sliding them backwards and forwards a few times and see whether that helps.

At least I won’t have to call out our local exorcist now.