J
Jeff Dege
- Jan 1, 1970
- 0
I've built a 418MHz RF receiver into a Radio Shack project box together
with a couple of relays. When I push one of the button on the
transmitter, one of the relays closes.
My intent is to wire this into the doorbell circuit, so I can ring the
doorbell remotely, when no one is there. I can then use this to
desensitize the dog to the doorbell - teach him to not get so excited
every time he hears it ring.
I have a clip for a 9V battery inside the box, but I also included a set
of binding posts so that I could power it from an external source. I'd
thought that I might be able to power it from the doorbell circuit. But
the truth is I don't know beans about what sort of power doorbell circuits
carry.
I know they run at a low voltage. That's clear from the wiring used. And
I can see the step-down transformer.
I also know that the solenoids in the doorbell itself have to be powered
by a DC current. Applying AC to a solenoid accomplishes nothing.
But I don't know whether the current is rectified at the transformer or
inside the doorbell. If the former, I might be able to connect it
straight to the 7805 voltage regulator inside the box. If the latter, I
need a rectifier circuit.
So - can anyone tell me exactly what sort of current I can expect to find
in a doorbell circuit? And what I would need to condition it before
feeding it to a 7805 voltage regulator?
--
I am myself persuaded, on the basis of extensive study of the historical
evidence, that... the severity of each of the contractions - 1920-21;
1929-33, and 1937-38 - is directly attributable to acts of commission
and omission by the Reserve authorities and would not have occurred
under earlier monetary and banking arrangements.
- Milton Friedman
with a couple of relays. When I push one of the button on the
transmitter, one of the relays closes.
My intent is to wire this into the doorbell circuit, so I can ring the
doorbell remotely, when no one is there. I can then use this to
desensitize the dog to the doorbell - teach him to not get so excited
every time he hears it ring.
I have a clip for a 9V battery inside the box, but I also included a set
of binding posts so that I could power it from an external source. I'd
thought that I might be able to power it from the doorbell circuit. But
the truth is I don't know beans about what sort of power doorbell circuits
carry.
I know they run at a low voltage. That's clear from the wiring used. And
I can see the step-down transformer.
I also know that the solenoids in the doorbell itself have to be powered
by a DC current. Applying AC to a solenoid accomplishes nothing.
But I don't know whether the current is rectified at the transformer or
inside the doorbell. If the former, I might be able to connect it
straight to the 7805 voltage regulator inside the box. If the latter, I
need a rectifier circuit.
So - can anyone tell me exactly what sort of current I can expect to find
in a doorbell circuit? And what I would need to condition it before
feeding it to a 7805 voltage regulator?
--
I am myself persuaded, on the basis of extensive study of the historical
evidence, that... the severity of each of the contractions - 1920-21;
1929-33, and 1937-38 - is directly attributable to acts of commission
and omission by the Reserve authorities and would not have occurred
under earlier monetary and banking arrangements.
- Milton Friedman