Thread: 240v sounder
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geoff geoff is offline
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Default 240v sounder
In message , writes
On 13 Mar,
Frank Erskine wrote:

Automatic light switches with an ORP12, a red spot transistor and a
relay.

And what about before semiconductors? Replace the red spot with a triode.
Neon for the timer.


Even I'm not that old ...

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geoff
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