I’ll build it for you, but first a few questions…

1. How can I be sure I’ll be paid?
2. Are you sure you can install it correctly?
3. What if it doesn’t work?

Of course there are more questions, but they come after accepting the job.

 

My question is: Why wouldn't you contact the guy who built the original circuit. You could ask him "How long has it been working" or "Did you have to make any changes."

 

My question is: Why wouldn't you contact the guy who built the original circuit. You could ask him "How long has it been working" or "Did you have to make any changes."

Yes. I contacted him as did many others on YouTube and he doesn't respond

 

Yes. I contacted him as did many others on YouTube and he doesn't respond

Maybe he burnt his house down with his device!?!?

 

Could at least have the courtesy of saying no thanks.

 

PB has one solution. One could also use an AC optocoupler and get rid of the diodes and capacitor: https://www.onsemi.com/pub/Collateral/MID400-D.PDF

That is one with logic output but there are several others at various distributors. Here is the search I used at Digikey.

 

Would have to figure out where to get VCC from, in order to use that coupler.

 

I remember seeing a thread/applicaton note about using an existing doorbell with the Ring doorbell and I believe it required that high powered resistor. As I understand it, Ring use the existing doorbell wiring to attach to the ring doorbell. That charges a battery inside the doorbell. That resistor is needed when you don't have a real bell with a coil. Some of the solid state musical doorbells won't work without the resistor mod.

This is what i remember - no time to search.

I'm not sure what everyone is fired up about?

The schematic in the video doesn't show where the RING doorbell connects. In a normal doorbell there would be a chime with some resistance. I believe the resistor is providing that resistance. Find the app note.

 

My purpose was to point out that the LED side might be AC and simplify the circuit. That is why I gave the link to the Digikey search. Not all types require VCC: https://media.digikey.com/pdf/Data Sheets/Fairchild PDFs/FOD816.pdf

 

I don't think he's burned his house down as he's responding to some questions just not the ones of people asking if he would build the device.

 

PB has one solution. One could also use an AC optocoupler and get rid of the diodes and capacitor: https://www.onsemi.com/pub/Collateral/MID400-D.PDF

That part saves you manually wiring up a diode bridge, but that's all. The raw output is a 120 Hz square wave, so it still needs filter capacitor. Also, it's max output current is 20 mA, only 10% of the project requirement, so it cannot drive the NuTone directly. Two opto-isolated devices in series?

ak

 

My purpose was to point out that the LED side might be AC and simplify the circuit. That is why I gave the link to the Digikey search. Not all types require VCC: https://media.digikey.com/pdf/Data Sheets/Fairchild PDFs/FOD816.pdf

But won’t the output go to zero at each zero crossing with that coupler?

 

That giant resistor bugs me. I get why it is so large - depending on the size of your doorbell transformer, it could deliver 2 A or more into a catastrophic short of some kind. Still, that's a big puppy running cold 99.99981% of the time. It would be smaller and cheaper to cut the resistor size by 75% and add a 0.5 A, 5 mm fuse in series.

Another way is to replace the resistor with a small current sense transformer. If you have a dead switching power supply of just about any nature lying around, the AC input common mode choke works well. So does the audio output transformer from a small, old transistor amplifier (ok, *really* old).

ak

 

But won’t the output go to zero at each zero crossing with that coupler?

Yup.

 

Here's https://support.ring.com/hc/en-us/a...-Transformer-Without-a-Pre-existing-Doorbell- the app note. It does use a 50 W, 25 ohm resistor that's in series with the doorbell, not being powered all of the time.

He said in the video he's using a FET opto-coupler.

EDIT: Typo

 

International Rectifier
p/n: PVAZ172N
https://www.infineon.com/cms/en/product/power/solid-state-relay/photovoltaic-relays/pvaz172ns/

$11.52 each, Digi-Key
https://www.digikey.com/products/en?keywords=PVAZ172NPBF-ND

ak

 

The circuit in the video is missing the RING doorbell connection. Connecting the resistor to a bush button accomplishes nothing. There is no RING doorbell in the "picture". The ring app note helps you figure that out.

The input to the NuTone mode is shown as a contact closure. He used a FET optocoupler. Details here is to figure out the lowest value resistor that can be used instead of the switch and find a FET coupler that has an on resistance by a factor of 2. Or just use an OPTOMOS relay with a low on resistance. A good designer would know the measured current too.

Zero crossings, bah humbug, it's full wave rectified and filtered. Looks like clean edges don't matter. The full wave rectifier can be one 4-lead part or four 2-lead parts

So, you can find parts that have a near 100% chance of working or invest some time to find the cheapest parts or do something in-between.
The opto-couplers are expensive. You can reduce their cost by knowing the operating point.

You could also add parts to make it more reliable and "complicated". Transorbs for transients and even a current source to drive the optocoupler.