[VoIP] Coin relay controller

[Mark Rudholm]

Mark Rudholm wrote:
> Donald Froula wrote:
>> Sorry, I should have read more carefully. I was using
>> two 120VAC:18VAC transformers with their secondaries
>> connected together for isolation and current limiting.
>> That provided the 170 VDC after filtering.
> 
> Ah, so you effectively constructed a 1:1
> 
> Mouser has small (100-200mA) 2:1 transformers
> that are quite suitable for this application.

Oh, also, If you connect a 120VAC:9VAC transformer
to the line, and then put an 120VAC:18VAC
transformer downstream of that, you'll have
constructed a 2:1 transformer.  A 9VAC transformer
is probably sitting in your parts bin...