ESP8266 Community Forum

- Fri Aug 28, 2020 3:32 am #88511 The value of the 100K was chosen to be higher than the 10K resistor which sets the delay time constant together with the capacitor.

It is not critical but it is in effect in parallel with the 10K (via the base) so will lower the delay time. It could be reduced to 47K or even 22K with small effect. It doesn't want to be too high as the base current needs to be sufficient so that the transistor turns hard on to pull the RST line low. RST has an internal pull up of the order of 10K, so 100K should provide sufficient base current to saturate the transistor.

- Fri Aug 28, 2020 3:49 am #88512

The value of the 100K was chosen to be higher than the 10K resistor which sets the delay time constant together with the capacitor.

It is not critical but it is in effect in parallel with the 10K (via the base) so will lower the delay time. It could be reduced to 47K or even 22K with small effect. It doesn't want to be too high as the base current needs to be sufficient so that the transistor turns hard on to pull the RST line low. RST has an internal pull up of the order of 10K, so 100K should provide sufficient base current to saturate the transistor.

Aaahhh, two super valuebale things learned:
* The relation between the two resistors to effect the delay time. Need to read up a bit on that! Thx!
* And that the the RSTs pullup to 10k. That I didn't know!

Thanks again! Can't wait to get to the next electric parts shop and get some capacitors. Sadly not one nearby and ordering feels stupid, as the shipping is gonna be >5 times higher than the actual package value

- Sat Aug 29, 2020 3:09 pm #88539 Hrm, one more thing: I realized there is no connection to GND :/ Did I miss something, or would I connect GND from the doorbell straight to a GND on the ESP?

- Sat Aug 29, 2020 3:38 pm #88541 ofcourse ...