The cat needs running water

He won’t drink from a bowl. So we want to use LittleBits to open a solenoid valve that I can put in under the sink. Hopefully I can find a 12V solenoid so I can power both the solenoid and LittleBits from the same power supply… I’m sure I can find a 24V solenoid. I won’t use a 120VAC solenoid.

I don’t want to even think about trying to train a cat to press a button. We should be able to use the Motion Sensor Bit. Does anyone have any experience with it’s range? If it’s not much then maybe it’s likely to get wet. What’s the best way to seal it? Silicone? Spray paint or varnish?

The 5V and 250ma from LittleBits is not enough to operate a solenoid. It’s not clear online if the Proto Bit will pass thru a different voltage other than the 5V control voltage from LittleBits, i.e. 12V. The website is also not clear how to wire the Proto Bit to power the solenoid or a relay. Does anyone know how to connect LittleBits to a solenoid?

Does anyone have any better ideas?

hello @tbutler997,
A few months ago I submitted a new bit to the bitlab which unfortunally did not get enough votes. It is a “relay bit” that could be used in your cat project !
It connects an external power to an external component (could be your solenoid) using a maximum voltage of 12V and a maximum load of 1 ampere.
It can be made with the perf board which is available in the HDK kit or can be purchased separately. The other components used (a transisor, a relay, a diode and some resistors and a LED)are not very expensive and can be bought from any electronic DIY shop.
This is the schematic of this relay bit:


This relay bit can be activated by any other bit in a safe way, the output of the relay is connected via the (red) bolted terminals and does not influence the LittleBits system at all.
I hope you can build your cat water feeder with this design, let me know if something might be unclear to you ! :smile:

Maybe @JackANDJude could tell you more about the motion sensor, I do not have this bit…

This is the relay perf board with the used components:

and two applications (examples):

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Hi @alexpikkert,
A Relay bit is so obvious to me. Of course they should build it. They seem to be stuck on electronics and doing things the electronics way. LittleBits are weak on connecting to other things.
Note I changed my my name.
I think the Power bits should handle 24v input like many control systems. Then of course a Relay bit that can handle 24v for connecting on the other end. It’ll probably be a lot easier to find a 24v solenoid valve. I’d like to see the Power bits have connectors to allow hard-wiring the power to the bit or to give a power takeoff. With a Power bit like that I could also use an powersupply/adapter, plug it in, not have to splice into the wires, then connect the takeoff to the relay and then to the solenoid. That be a lot more elegant that sticking a splice somewhere. Maybe I’ll solder one on my Power bit.
I’d like to see the end pieces handle a clip of some sort. Then the backboard, so much like a breadboard, is just one option.
Thank you so much for the schematic. If I use the the HDK then my little girl will be happier since she’d like to use all LittleBits. She recently learned to solder. So maybe it’s best LittleBits doesn’t make a Relay bit. It’ll give her something to make. Can I get back to you for another schematic if I have to go with 24v or need more amperage?
Now to contact @JackANDJude.

Hi @alexpikkert,
I’m familiar with old-school relays. Can these little ones have a time delay?
If you’re in a schematic mood, can you think of how to make a heat/IR sensor bit? A Motion Sensor bit sounds great except he’ll be moving most near the running water. That’s where the water is most likely to trigger the sensor and may keep it running forever. But the cold water should let a heat sensor go back to sleep.
Thank you

Hello @TimNRobin,
The littleBits system is a very open system. Many things can be done using only the available bits, and the system is used from schools for learning classes where young kids can experiment with electronics to old school experienced users.
I think using 24V or higher could be dangerous for kids in schools, that’s why it is understandable that LittleBits limits their operating voltage to a safe 5 V DC.
The official connection to higher voltages in a safe way is done with the IR controlled power outlet you can purchase in the smart home kit in the shop.
In my relay bit I used a miniature relay from Zettler type AZ822-2C with this datasheet:

As you can see, I used a safety margin in my Bitlab specification of 12V 1A. In reality the contacts can switch 24 V DC 1Amp!.
If you need more you can select another type of relay, as long as the coil (which is connected to the littleBits system) operates on their 5V DC.
Also Axicom sells these relays, see:

A type D2N V2305 worked also fine. The contacts of this relay can even swich more amps.

Hello @TimNRobin,
About time delay:
Littlebits has a timeout bit type I27, with this bit you can delay the closing or opening of the relay by setting the delay with a little screwdriver.
The best way to discover the solution you need is experimenting… :bitstar:
There is a temperature sensor but I think it works not fast enough for what you need.
You could use a light sensor or an IR sensor to detect movement also. Or a small floor surface, activating the roller switch bit…
Happy tinkering and keep posting your progres!

All the Bits are like cats: they don’t like to be wet. :cat: :umbrella:

Hi @Timnrobin! Nice to meet you. :smile:

The motion trigger is very sensitive. Restricting it’s range is usually what people do. Find more on that here:

I tried this morning, and bunny can set off the motion trigger with a cone of paper taped around it to restrict its range of detection. She puts her nose at the top of the cone, and an led turns on.

I agree with @alexpikkert that a timeout module would help your 5v relay to remain on momentarily - for as long as 5 minutes per incident. You can hook the relay up to the proto bit. Check out my motion sensitive bubble machine for an example, but replace “hacked bit” with proto bit.

I think you can place the motion detector strategically around the sink so it won’t get wet.

I have a 12V solenoid valve switch. It would add 2-3 inches to your faucet, and you’d probably need a coupler.

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@TimNRobin I hope you come tomorrow to our monthly Community Call. During the first half there will be guest speakers and announcements, and then we break into rooms to show projects and ideas we have. :smile: