# RF circuit for powering solenoid

#### absoluteZro

Joined Nov 12, 2011
19
[my knowledge of circuits is pretty bad, but I am willing to read anything I need to on the allaboutcircuits textbook]

The specs show this: Main Parameter of Receiver Modules:
Control Mode: L4: Latch Type(Key A open, Key B close and Vice vers)
Working Frequency: 315MHz
Working Voltage : DC5V
Working current : Less than or equal to3mA (5.0VDC)
Working principle : superregeneration
Encode chip: PT2272-L4 compatible
Response rate: >-105dBm ( 50hmic )
Pin Assignment:
-D0: Output 0
-D1: Output 1
-D2: Output 2
-D3: Output 3
-GND: Ground
-VT: Switching voltage
-VCC: Supply Voltage

The purpose of this transmitter/receiver will be to turn a solenoid on/off. I initially thought I needed a switch, but I don't think RF controlled switches exist...probably because that is what the receiver essentially is (I think?).

Anyways, the solenoid is a 12v push type. I haven't decided on one yet, but it will definitely be 12v so I can use 23As.

The questions are: How do I wire a circuit using that receiver to turn on the Solenoid, then stop supplying power to it?
During my reading, I found that since Solenoids are inductors, I should have a diode attached to the solenoid so current doesn't flow back and hurt my receiver. Is that true?
What does that Working Voltage/Current mean? Will it still work with a 12v power supply?

(Also, if anyone is knowledgable in Solenoids, I was trying to find a practical guide to give me an idea of what 1N of force would be like. Something like the tables that tell you 30dBa is a whispering conversation etc.)

#### praondevou

Joined Jul 9, 2011
2,942
What does that Working Voltage/Current mean? Will it still work with a 12v power supply?
I doubt it. That looks like it's nominal supply voltage/current ratings. They don't give absolute maximum ratings and unless you know the circuit I wouldn't use any other voltage than what they put in their description. You will need to drive a transistor which in turn will drive the solenoid.

However, wireless switches do exist: http://www.ebay.com/itm/12V-10A-315...454?pt=LH_DefaultDomain_0&hash=item2a1453d7ae

#### absoluteZro

Joined Nov 12, 2011
19
So if I have that, all I have to do is put my batteries, switch, and solenoid in a circuit?

It says working voltage: 12VDC. But also suggest a power supply of more than .5A. Since I need to provide a lot of power to the solenoid, if I have only 12v power supply, should I be worried about the receiver/switch using up some of my power?

#### praondevou

Joined Jul 9, 2011
2,942
So if I have that, all I have to do is put my batteries, switch, and solenoid in a circuit?

It says working voltage: 12VDC. But also suggest a power supply of more than .5A. Since I need to provide a lot of power to the solenoid, if I have only 12v power supply, should I be worried about the receiver/switch using up some of my power?
Since you use a LOT more current for the solenoid why would you worry about 500mA for the receiver circuit? Btw, 500mA is probably the maximum current when all relays are turned on.
If you search for "wireless switch" on ebay you will find a lot like these. Chinese made, very inexpensive and with one or more channels and for different voltages.
Note that 10A doesn't mean you should pass 10A through these tiny relays, that's a maximum rating.

With the small relay you switch either a bigger one with then powers the solenoid or you power the bigger relay directly with the same signal that powers the smaller relay, deactivate the smaller which is mounted on the PCB and pull to wires to your bigger one.

Make sure, if you swap the relays, that the one you use has a coil resistance similar or higher than the one that was mounted on the PCB.