EzViz DB1 - Chime / Powerkit question

mucse

n3wb
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Hey guys,

I'm a bit lost in space since a few months now i try to get the DB1 doorbell running with an additional chime.
I purchased 2 different chimes, and no success at all (Seeyoutube video for my latest try)

Now, what i also tried is testing the 2 wires from the power kit with my multimeter...
In "standby" the only thing what i can measure is around 0.5VAC. Once i press the bell button, the volatge goes up to 0.6 VAC. Is this really intended? Whats the power kit actually doing, from what i read here it should supply then the chime with power, so i should expect 12 Volts in my case, i guess? Is my powerkit maybe broken?

Or do i oversee something? I need urgently an "external" alarm, when someone rings, since my mobile phone isn't always with me. Is there any other chane to do this? Maybe plaing some audio on a google home device using IFTTT or similar?
Is there any other device which i could use instaed of the powerkit?

Thansk for any hints!

 

jlpiercenc

n3wb
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I just got a DB1C installed and wondered what was in the power kits. I popped it apart and saw two chips: an LCB710 which is a solid-state relay with 1A @60V capacity. The other chip is a LM2903 voltage comparator: basically an op am with no feedback used to compare two voltages or a voltage vs a reference. There are numerous large size resistors on the PCB. The out-of-circuit resistance is 4 ohms. My guess is the relay is normally closed and allows current to flow around the coil of the chime's electromagnet so that the chime doesn't buzz. The comparator notices when the doorbell camera system starts to draw a significant amount of current indicating that the bell button is pressed. At that point the relay opens and then all the current flows through the electromagnet ringing the chime normally with full power.

That's just a guess, but you need some kind of kludge like this to feed power to the camera (and IR illuminators) without buzzing the chime, I would think. The camera is rated at 6 W (so approximately 0.3A at 20V.). I noticed it gets warm at night when the IR illuminators are active.

I noticed on YouTube videos suggesting you can put an 8 ohm 1/2 W resistor in the place where the power kit goes (for folks w/o a power kit, I guess). Some responses indicated the resistor burns up. That's not surprising. The chime circuit doesn't have many components but it seems to me its behavior is complicated. There's a step function input with the bell switch; there's the induction of the electromagnet; and the electro-mechanical effect of the ringer hammer. So L is changing a lot, voltage is leading current likely a lot, etc. But just considering a resistive circuit and Ohm Law for DC that approximation is something like 20 V across an 8 ohm resistor for a moment. So P = V**V / R = 50 W. If someone holds your door bell closed (or pressed it repeatedly) for a while that's a lot of heat in a 1/2 W resistor.

I may be totally off here on any of this and would welcome being set straight. I like to know what's going on in my house especially what electrons are up to!
 

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