External Telephone bell as an alarm

[Ste]

I have found an external telephone ringer, which is basically a double coil with a striker that hits two bells as the coils are energised. It has been powered via the telephone line, but Id like to adapt it to sound as an alarm activated by a basic circuit incorparating a door contact as the trigger .

I know next to nothing about telephones and their operation, but im told I will require  "about 50 - 70 volts AC at 16-25 Hz".  Obviousley I havent got such frequencies or voltages, so my question is, can I buy a little basic box of tricks to convert normal mains voltage and frequency to the desired level.

Its only a small project to do whilst in lockdown, so the budget is minimal

 

[HarryA]

You can get a 120 volt to 48 volt transformer for about 15$ off Ebay. That still leaves you with 60 hertz which would be expensive to converter down in frequency. Perhaps 60 hertz  would work? I used a pocket am/fm radio for a signal device; just opened the lead to the battery for external connections. You can get one for 10$.