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What is this three-legged component?

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Athosworld

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When I opened an old CRT TV remote, I found this component that looks like a ceramic capacitor.
99096B98-85BD-4626-BB71-A1720A7CD61E.jpeg
 
It is a ceramic resonator, one with the loading capacitors built in - the centre pin is the ground for the capacitors.
 
Yes it's a ceramic resonator, seems a higher frequency than most though, I seem to recall they were usually 455KHz or so? - they commonly break off, due to the remotes been dropped. I suspect it's probably a remote that uses a micro-controller, rather than a custom remote IC.
 
The outer two are the direct connections to the resonator, then the centre one is (typically) ground, with an appropriate value load capacitor to each outer terminal.

The commonest crystal oscillator configuration on microprocessors, or using CMOS gate etc., uses a crystal with a capacitor to ground from either end.

Those ceramic resonators are a low cost equivalent to a quartz crystal, with lower frequency accuracy. The three terminal ones also combine the capacitors to reduce the component count.

eg
osc33.gif



xtal_osc.png



A three terminal resonator replaces the separate crystal and load caps.
 
Yes it's a ceramic resonator, seems a higher frequency than most though, I seem to recall they were usually 455KHz or so? - they commonly break off, due to the remotes been dropped. I suspect it's probably a remote that uses a micro-controller, rather than a custom remote IC.
That explains why it fell off so easily and without desoldering.
 
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