I can not close 12VDC brass solenoid valve.

[haroldl]

I have an Uno, e-Tape and Geerte brass valve #996 for liquid flow control, I am also using a 12 volt dc external power supply. my sketch is reading the e-tape levels fine. When level is less than 300 set digitalWrite on pin 7 - HIGH. The relay's led is now on. The solenoid will open and start the flow. When the level reaches 450 my else statement calls digitalWrite on pin 7 - LOW but does not close the valve. I am using a Sainsmart 4 channel solid state relay, I am using only one channel on the relay , all works as expected except for closing the valve. My serial out confirms the else statement executes. The led on the relay turns off but the flowing continues unless I turn off the external adafruit regulated power supply manually. My circuit has the Uno pin 7 jumpered to bread board going thru a 1k resistor then directly to the relay's 5 volt input. I am asking why can I not close the cut off valve by setting digital pin 7 to LOW ?

[Franklin97355]

Could you tell us how you have it connected and powered?

[haroldl]

My Uno is connected and powered thru my laptop's usb. The Uno provides 5 volts and ground to a bread board. I connect 5 volt from the bread board rail to the relay's VCC, then connect bread board ground rail to relay's GND. Uno's digital pin 7 connects to relay's IN1, no resistor is used. The IN1 led will turn on and off as expected.
The brass valve has a yellow and a blue wire. I have connected the yellow to positive 12 volts on the Adjustable breadboard power supply. The blue wire connects to relay's D1 - screw terminal one, D1 - screw terminal two connects to adjustable power supply ground. The external power is supplied by an A/C adapter with a output of 12VDC, 2 amps.
This circuit will turn on channel one led and open the cut-off valve, I just can not close the valve when digitalWrite 7 LOW is executed.
If I use relay channel 2,3 or 4 I get the same as described for channel 1. I am guessing, I need to pull pin 7 to zero when the digitalWrite LOW is called, if so how can I do it ?

[adafruit_support_bill]

When pin 7 goes low, does the relay open?

[haroldl]

In my sketch setup function,

pinMode(valvePin, OUTPUT);
digitalWrite(valvePin, LOW);

no the valve does not open when Low is called.

[haroldl]

May I add, I used a 12 volt fan to test relay is activating when pin 7 is set to HIGH, the fan will start. When pin 7 is set to LOW, relay led will turn off and the fan will stop.

[adafruit_support_bill]

no the valve does not open when Low is called.

The question was "When pin 7 goes low, does the relay open?" If it is a mechanical relay, you should hear a click.

[haroldl]

I am using a Sainsmart 4 channel solid state relay.
no it does not open and stop the current flow,
IE: When the program first calls digitalWrite pin 7 HIGH. The relay does close and output voltage to valve goes from zero to 9.36 volts, when digitalWrite pin 7 LOW is called the voltage remains 9.36 but the relay led does go out.

[haroldl]

If I remove the positive and negative leads from the valve and connect them to a 12VDC fan the fan will cycle on and off based on sketch logic, the only issued is why would the brass cut off valve not respond to digitalwrite low as the fan does ?

[adafruit_support_bill]

when digitalWrite pin 7 LOW is called the voltage remains 9.36 but the relay led does go out.

Not sure why the relay output would stay high. But I'm not familiar with that Sain Smart board. It may require a pull-down resistor on the input.

So the valve opens and closes if you manually connect/disconnect the 12v source?

[haroldl]

Yes, with positive from power supply connected to valve and touch the negative lead to valve, it will open and liquid will flow until I disconnect the negative lead. The valve does close. I tried adding a pull-down resister 1K not sure if correct size, but no joy. Can you recommend a relay, I would prefer on a breakout board 2 or 4 channels that is known to work with the brass solenoid valve sold by adafruit store ?

[adafruit_support_bill]

Any mechanical relay board should work. I'm pretty sure SainSmart makes a mechanical relay board. Solid-state relays are quieter and will last longer, but they are generally designed for either AC or DC switching. I suspect that the one you have is designed for AC, so it doesn't properly switch a DC load.

[haroldl]

Mechanical relay board worked. Thank you so much...