12v relay Diagram for a 12v solenoid

[halloweenrick]

I need a diagram for a 12v relay to a 12v solenoid to run off a Prop-1.

[JackMan]

Here ya go, pretty simple stuff. The relays you have are SPDT (single pole double throw). If you are looking at the bottom of the relay there are 3 pins on one end, the center pin is C (common). The 2 pins on either side of C are the coil connections. The 2 pins at the other end are N.O. and N.C. (normally open, normally closed). The diagram on the bottom of the relay shows which is which.

Just as a reminder, there's no need to address your posts to a particular member, there's lots of people here that can help when you need it. It would be a good idea to modify your post and change the subject line to something that suits the content so others can find it in a search. Thanks.  ;D

[JonnyMac]

You'd be helping your friends at EFX-TEK by using regular email instead of personal messages on the forums as those messages and any contents burn up server space that only serves the private parties. Public posts that everyone can access and learn from are no problem; that's what these forums are for.

Thanks for understanding.

Jon

[halloweenrick]

Sorry Jonny.  I'll delete my messages saved and feel free to delete this topic as I have saved the schematic.
Thanks Rick

[JonnyMac]

Public topics are fine because everyone can learn from them.  For private exchanges, please use regular email instead of forum PMs.  Thanks.

Jon

[gadget-evilusions]

What is the point of the diagram? Obviously I can see it's using a relay to control a solenoid, but doesn't it defeat the purpose of operating a high wattage solenoid (I assume the point of using the relay) if you run the +v and ground thru the prop-1. I don't see an advantage. I have used relays to operate solenoids from a prop-1 when the power draw was over what the ULN could handle, or when the voltage was over what the prop-1 could handle.

[JackMan]

The advantage would be that the current needed to operate the solenoid wouldn't be flowing thru the ULN. Oviously this isn't a concern if the mA draw of the device is within the limits of the ULN.

[bsnut]

What is the point of the diagram? Obviously I can see it's using a relay to control a solenoid, but doesn't it defeat the purpose of operating a high wattage solenoid (I assume the point of using the relay) if you run the +v and ground thru the prop-1. I don't see an advantage. I have used relays to operate solenoids from a prop-1 when the power draw was over what the ULN could handle, or when the voltage was over what the prop-1 could handle.

I understand that, I am a little late on this topic. I think point of the diagram is what I started doing and that is, providing a drawing makes it easier for someone to understand what they're talking about.

[gadget-evilusions]

I understand posting a diagram, I was just trying to get the purpose of using the relay with still routing power thru the prop-1 partially.

What was the wattage of the solenoid that was being operated?

[BigRez]

I was wondering the same thing Brian...  If you're using the V++ and GND to power the Solenoid, why not just connect it to V++ and OUTx and eliminate the relay?  If the Solenoid is drawing too much power and has its own power supply, then the relay is used to switch GND open and closed but there's no connection from the prop-1's V++ to the Solenoid - it has it's on power but a common ground.  Is this correct?

[JackMan]

If your connected devices require more current than the Prop-1 power supply can deliver, yes, you would need an aux PS to operate those devices and a relay is a way to accomplish that. Lets say the solenoid draws 550mA and you are powering the Prop-1 with a 1000mA PS. You have enough available power to satisfy the Prop-1 and the solenoid but the ULN can't handle 550mA. If it's wired like the schematic, the 550mA needed for the solenoid is not flowing thru the ULN, it's simply coming directly from the PS thru the V+ and GND of the Prop-1. The only current passing thru the ULN would be the very small amount needed to energize the relay.

[BigRez]

OK, that makes sense and I understand that, but in that scenario, why then would one want to use the relay?  It seems that unless the relay is a multiple-throw relay (it's not) that's switching multiple items at the same time, it's just extra hardware that isn't needed; The solenoid could use V++ and OUTx without a relay.

Maybe the confusion is coming from missing info that has been removed or communicated elsewhere?

[bsnut]

Maybe the confusion is coming from missing info that has been removed or communicated elsewhere?

I agree with this as well.

I understand what Jack is saying as well, with using one power supply. I also understand what Brian and Mike are saying as well. One thing that I would be concerned about is the current through the switch and traces on the Prop-1 itself. You don't want to over do it or you will have problems with blue smoke. I keep my voltage source for my high current solenoids on different power supplies and they are fused to help protect the circuit and easy to troubleshoot.

   
 

[JackMan]

OK, that makes sense and I understand that, but in that scenario, why then would one want to use the relay?  It seems that unless the relay is a multiple-throw relay (it's not) that's switching multiple items at the same time, it's just extra hardware that isn't needed; The solenoid could use V++ and OUTx without a relay.

Maybe the confusion is coming from missing info that has been removed or communicated elsewhere?

The ULN can only handle 500mA max with all OUT terminals combined. If one device is drawing more than 500mA and it is connected to an OUTx you will blow the ULN. If you are using multiple OUTx terminals at the same time and your devices are drawing more than 500mA combined, you could blow the ULN. I personnaly don't like to push it to its limit if I feel that things are close. You're not gonna smoke the Prop-1 traces or the switch using a 1A PS.

[JonnyMac]

The ULN can only handle 500mA max with all OUT terminals combined.

Actually, it's about 1.2A the load is spread across all outputs.  When only one is running, it can handle up to 500mA.