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Thanks for the suggestions,I only know some of the electronics symbols, could you tell me what the thing marked "PBS", and what's the thing marked "C" are?thanks.
Perhaps you should've done a simple google request before posting.Old phones used a hand cranked AC dynamo, that operated the AC ringer bell. Landline phones still work the same way but you don't need to crank a dynamo to generate the AC it's transmitted over the lines.
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