First time i've posted to this group.
I was looking at a website that sells battery-operated digital locks, like the ones you see attached to doorknobs in a hotel room, or a restricted door in an office building.
Do those things use a small motor to unlock and lock the door? Or is there a solenoid? Sometimes i think i hear a motor; sometimes i don't hear anything at all when the door unlocks.
Thanks, Mike
be advised.. they are VERY pricey... dont have 'sticker shock'..
--Shiva--
I know that they can start at anywhere around $700. That's way too expensive for a closer(?) and electronics. THe electronics is only worth around $30, and probably the keypad takes up the most cost. Other than that, you're paying for $600+ worth of metal.
But my question was - is it a solenoid or motor? I wonder how batteries can supply enough juice to toggle a solenoid. (Perhaps the charge builds up, like in a camera flashbulb.)
new safe locks can use motors, and they run quite well on 9 volt batteries.. same thing here. its the POWER increase thru reduction they gain..
solenoids take way too much power, for it to be run 'good' on batteries IF there is a 'sufficient load' for them to overcome --Shiva--
locks,
I would never use such a piece of shit, but yes, an electric motor moves the bolt.
Depends on the design. Advantage of a motor is that there's no power drain to hold it unlocked; advantage of a solenoid is that relocking it doesn't drain power. Which is better depends on how the lock will be used.
I would guess that the residential versions are mostly solenoid because
-- among other things -- it can be cheaper to manufacture.
Note too that what you're hearing may be a solenoid being operated on AC, which will tend to buzz. A solenoid operating on DC is usually silent. Depending on the application that buzz may be considered either a nuisance or an advantage, and folks select the behavior they want when they're setting up the system.
It really depends on the design. I've seen solenoid (click) and motor driven as well as a neat design that enables the lever.
The last design uses a small pin to connect the door knob/lever to the spindle. The pin is spring loaded. It's forced back (and locks in that position) when the knob is fully turned, disconnecting the knob from the spindle. The knob can be turned all you want when the pin is retracted. No electricity is needed to lock the door.
The pin is released (reconnecting the knob to the spindle) when a very small solenoid is activated. The solenoid is very low power and uses a very short pulse to unlock the door.
Other variations use a solenoid to engage a pawl that connects the knob to the spindle. These typically are timed. Again, low power only when thge knob is about to be turned. Turning the knob actually provides the force needed to retract the bolt.
Daniel
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