ESP8266 Community Forum

- Wed Jan 06, 2016 12:30 pm #38061 I connect 4 Relay by use ULN2003 for drive Relay. when I connect 4 wire from ULN2003 to NodeMCU and power on NodeMCU . Then NodeMCU can't open web page.
But , If I connect only 1 wire from ULN2003 or open NodeMCU before connect 4 wire , Then it can open webpage.
I want to use only 1 adapter . Current adapter is 2.5 A . How to fix it ?

- Wed Jan 06, 2016 12:58 pm #38063 Which GPIOs are you using to drive the ULN2003 ?

- Wed Jan 06, 2016 3:36 pm #38076 Is the voltage at esp 3.3 volts with relays connected, ?
Is the voltage adapter regulated or just a wall wart?
If yes to both questions , I would suspect electrical noise.
Try decouple relay driver with 47uf and .1uf cap....ensure good ground.....

- Thu Jan 07, 2016 12:15 am #38108

Is the voltage at esp 3.3 volts with relays connected, ?
Is the voltage adapter regulated or just a wall wart?
If yes to both questions , I would suspect electrical noise.
Try decouple relay driver with 47uf and .1uf cap....ensure good ground.....

Yes both. If I connect ground from uln2003 to adapter then ESP not work.



But If I power on ESP with not connect uln2003 ground to adapter then it work



How to make good ground.