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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment

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Old 5th Dec 2017, 9:37 am   #1
Sparks
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Default Sterdy door phone handset/cradle

Quick question. Can anyone please tell me what this component is inside the cradle body ? Is it a transformer, buzzer or something else ? I haven't a clue. Thankyou.
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Old 5th Dec 2017, 5:42 pm   #2
rambo1152
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Default Re: Sterdy door phone handset/cradle

I think it is the buzzer that announces someone at the front door.
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Old 5th Dec 2017, 5:58 pm   #3
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Default Re: Sterdy door phone handset/cradle

Thankyou Rambo. If so, any idea how I can test it ? The unit isn't active, it's purely decorative so it doesn't matter too much if it doesn't work. Thankyou.
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Old 6th Dec 2017, 7:12 pm   #4
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Default Re: Sterdy door phone handset/cradle

I guess it's just a question of applying a voltage of sorts across the terminals to see if the buzzer works. What would be a suitable value ? I don't want to overdo it and risk damaging the unit. Ta.
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Old 6th Dec 2017, 9:39 pm   #5
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Default Re: Sterdy door phone handset/cradle

If it is a buzzer, I can't see any interrupter contacts, suggesting that it works on AC.

What is the resistance of the coil? I can't see how many noughts there are.

Is there a gap between the coil cheek and what looks like a piece of flexible magnetic metal?
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Old 7th Dec 2017, 7:42 am   #6
dagskarlsen
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Default Re: Sterdy door phone handset/cradle

Not easy to guess on such voltage, but other buzzers for 10-12 V AC I have seen has had around 100 ohms resistance, so I would take the chance of try for 1 second.
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Old 7th Dec 2017, 9:58 am   #7
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Default Re: Sterdy door phone handset/cradle

Some more pictures in the hope they help. The coil thing says 100 ohms. The flat piece of metal at the bottom of the coil is quite thin and flexible. There are also a red wire and a black wire attached to either end. A hook switch is attached to the top - it breaks a circuit when the handset is in place and makes it when it is lifted.

Thankyou for your replies folks.
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Last edited by Sparks; 7th Dec 2017 at 10:09 am.
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Old 7th Dec 2017, 10:19 am   #8
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Default Re: Sterdy door phone handset/cradle

Definitely an AC Buzzer.

Try powering it from the output of a bell transformer, starting with the lowest available voltage. It would be advisable to check the continuity of the coil first.
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Old 7th Dec 2017, 10:21 am   #9
Sparks
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Default Re: Sterdy door phone handset/cradle

Thanks Graham. I don't know if it's significant but the handset has a No.16 carbon mic so obviously some sort of voltage is supplied to the unit.
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Old 7th Dec 2017, 10:23 am   #10
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Default Re: Sterdy door phone handset/cradle

The supply to the telephony parts of this will be DC, possibly 6V or lower.
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