ESP8266 Community Forum

- Fri Dec 11, 2015 8:54 am #36220 Wow. Thanks for all the replies, active forum

I've attached a quick drawing (ain't pretty, but Paintbrush is all I have at the PC I'm at now, away from home). I did it from memory; not sure if the Pull-Up was 100K (will check tonight). For test purposes I connected the bell directly. Obviously this would not be the end solution

@Eyal. I hadn't thought of this, so by measuring the voltage before and after the resistor I can derive the current passing through it?

@Kenn. Yeah I kinda had a feeling that it was a bit of a dirty thing I was doing. I'll look into what MOSFET's can do. What I'll probably use is one of those all-in-one AC/DC converters such as the VIGORTRONIX VTX-214-005-103, which gives me 900mA on 3.3V from 220AC, at a reasonable efficiency in a mobile package. Thanks for the extra info tho.

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- Fri Dec 11, 2015 9:37 am #36224 Do you means that your driving the bell directly from a GPIO ?
GPIOs are limited to maximum of 12mA, it is not enough to drive such device directly.
It can even damage your ESP permanently.
You really need some MOSFET to drive it.

For the button, the pullup of 100K is not strong enough, I would suggest to reduce it to 10K.

- Fri Dec 11, 2015 10:32 am #36226 No, I'm not driving the bell from GPIO, I know it might fry the board The bell is rated at I believe 200mA, can't be a good thing to put that through a delicate digital port. The 3.3V on the diagram are the 3.3V pins from the regulator on the board!

Ok, so, back to the original question. With D1 attached there is not enough power left to drive the bell.
Not that it matters that much, as I will use a mosfet or external AC/DC, BUT, it still bothers me.. I still think it's odd

@martinayotte. I'll try 10K, see how that works out.

- Fri Dec 11, 2015 11:02 am #36227 I don't think you have issue with the button, although the pullup will be better with 10K.
The important stuff to figure out is the bell. So since you say "I will use MOSFET", for now how do you drive it ?
Is the bell really a 3V one ? it look pretty rare. Do you have a picture of the bell, because old ones are usually 12 VAC.