ESP8266 Community Forum

I'm working on a project to monitor and water my plants using ESP8266 at the core. I will be powering the pump and solenoid valve(s) using a 12V motorcycle battery (or similar). The valves draw about 100 mA and the pump draws about 400 mA.

This should be a fairly simple question, but I'm getting lost in some of the details and nomenclature. I'm familiar with the concept of transistors and relays and also aware of the fact that the ESP8266's 3v3 logic signal is relatively low compared to what many transistors or relays will need to be activated in order to drive a 12V signal. It seems that there are transistors and relays that operate at logic level voltages.

In this situation, a relay seems overkill, and I think a transistor should do the trick just fine. I will have 1 pump and up to 3 solenoid valves all running on 12V, so it would be nice to have one chip act as 4+ "switches".

I'm thinking that one of these parts will do what I want it to do:

Darlington Driver 8-Channel ULN2803 DIP
https://www.sparkfun.com/products/312

or

ULN2803: 8 Channel Darlington Driver (Solenoid/Unipolar Stepper) - ULN2803A
https://www.adafruit.com/products/970

Do these both seem like a good choice for what I've described above? Looks like the Toshiba one from Adafruit has a higher V_I(ON) requirement value, so perhaps doesn't work as well with 3v3 logic signal? Any other key items I should pay attention to on the spec sheets?

Motors and solenoids can be quite "dirty" when powering them; I would use a relay board.

eduperez wrote:Motors and solenoids can be quite "dirty" when powering them; I would use a relay board.

Any suggestions on a specific 4-channel relay board that works with 3v3 logic level and draw less than ~20mA per channel? Looks like most boards work with a 5V logic signal and/or require more current.