Tiny Greenhouse Control. Please Help

Hello everyone,

I'm playing around with a box Ive built to germinate seeds in a controlled environment, and I'm looking for some advice. I'd like to get control of this 5V DC USB powered fan, http://www.amazon.com/gp/product/B00080G0BK/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1 and have the flexibility of adding a small motor, small water pump, and some LED Christmas style lights in the future. I'm looking at the relay boards listed below. Wondering if there is one that would handle both DC and AC? and what type of power supply(s) I would need. (seems like people on amazon are ordering 9V wallwarts to go with boards like these)

View live webcam of grow box here: http://www.ustream.tv/channel/ben-s-grow-box-cam


I have not used these particular boards but have had good luck with similar. The second one in particular–the one with real relays. From the specs:

Equiped with high-current relay, AC250V 10A ; DC30V 10A

Yeah, relays work with either AC or DC. The specs limit you to 30 volts DC, which is PLENTY to run your little fan. Those relays will also handle some pretty hefty motors, water pumps, and lights. Even heaters if you want. 10 amps X 250 volts is 2500 watts. Theoretically, it could handle a 3 horse pump.

The "FET Switches" board is for DC only. Unless you have a specific need to be able to "dim" a DC light then the second board, with electromechanical relays, would be preferred.

The relays on the second board are designed to be powered by a 5V supply, but anything ~5V to 12V should be fine.

Yourduino.com has an excellent tutorial for both types of boards: http://arduino-info.wikispaces.com/ArduinoPower

Awesome! Thanks so much for taking the time to reply. I did see that the relay board is capable of AC & DC, however, today i read that these relays are fairly loud. This would be an issue. How about if I started with one of these just for the fan and maybe a small motor, and then if i needed to add other stuff I could get a solid state relay board in addition.


If this looks good, id just need one of the 9v wallwarts to power it?

Thanks again XD

The relays are audible if you listen for them but I wouldn't call them "loud". It's just a light "click" when they turn on or off, and assuming you encase your electronics in any kind of enclosure you'd probably never hear them unless you really tried.

Thanks Chagrin,

This helps a lot. I think ill go for one of these then: http://www.amazon.com/SainSmart-4-Channel-Relay-Module-Arduino/dp/B0057OC5O8/ref=pd_sim_indust_2

Anyone have advice on the type of power supplies to purchase? Im seeing that it's best to use one supply for the arduino diecimila, and another for the above mentioned relay board to switch a 5V USB fan, and a small DC motor. Would two 9V walwarts cover this?

Here's a link to the live webcam that is currently inside the grow box: http://www.ustream.tv/channel/ben-s-grow-box-cam

Ben :slight_smile:

Just need a little help wiring up these components so I don’t hurt myself or the arduino. :sweat_smile: Ive read up quite a bit on it, but still unclear. I hear that I since I want to power the relay independently I should be moving the jumper pin?

Ive got a Diecimila that will be powered by usb. I need it to control the fan and lid lights via the 2 Relay module.

I’d like to power the relay using the 100-240V AC, 9V DC 1A Wallwart. Then hook the LED lights and 5V fan to the relay. Then control them all with the arduino. Here’s a photo of what ive got. Any help would really be awesome!

Per http://arduino-info.wikispaces.com/ArduinoPower the jumper between VCC and JD-VCC should be removed. The two digital outputs (IN1 and IN2) and the adjacent VCC are then connected to the Arduino. The GND and JD-VCC in the other row are then connected to your 9V power supply.