Hello everyone!
I'm new here and I hope to write on the right side. I made a quadcopter for my licence project and I want to add some external stuff but I don't know if it's possible. The controller is APM 2.6 with JR-8103A RC and I'm thinking to set a button on RC to turn on a LED or an electromagnet ( to pick up a cube from the ground ). Can I do this? I have just 3 days to do it and I hope to succeed. Thank's!
Replies
You won't run it through your flight controller. It'll be like a servo directly off the receiver. They make channel switches that contact when the channel exceeds a 50% threshold, but with three days you don't have time for shipping.
If you can get a small servo, you should be able to connect it directly to your receiver and possibly actuate a switch. the easiest would be a mercury switch mounted to the servo wheel so that, at rest, the contacts are clear, and when the servo is actuated, it would flip the switch upside down, immersing the contacts in conductive mercury. That way, it would take no real torque to make the connection and maybe no auxiliary power or relay would be needed.
Thank's for reply! I have time until monday. I was thinking to connect directly to receiver, but I didn't know if it will work ... later I saw at the copter.ardupilot.com that they made an Eletro Permanent Magnet and it function in this way, but I can't buy one now ... It's interesting your idea with the servo, but I didn't understand how can I grab something from the ground :-? ... Can you explain this? Maybe I will be able to do it until monday. Thank you very much!
The problem is actuating a switch using only the power from the receiver, so the servo cannot be large enough to physically flip a toggle switch. That's why using a mercury switch would work.
If the servo wheel is aligned perpendicular to the ground with a mercury switch on it, as it rotates, the mercury makes or breaks contact with the contact points inside the capsule, completing the circuit that drives your electromagnet which is drawing power from your flight battery, completely separate from any power your receiver might supply.
Again, all this would be moot if you had the time to order a solid state switch/relay for this purpose.
If you don't understand what a mercury switch is, picture a cylindrical drug capsule with two tiny wires imbedded just a millimeter apart in ONE END. The capsule contains a drop of conductive liquid, in this case, mercury. When the capsule is held with the contact pins up, the mercury is at the other end and the contacts are not shorted by the liquid, but turn the capsule over 180 degrees, and the drop of liquid pours to the other end completing the circuit, and you have effectively actuated a switch with virtually no torque -- certainly less than required to flip a physical switch. The smallest servo available can easily rotate a mercury switch. All you have to do is make sure the wires are loose enough to let the capsule move.
Here is one from Amazon. Your local electronics store, or electronics surplus should have cheap ones too. Sometimes they're used in car alarms.
http://www.amazon.com/Omega-AU46-MERCURY-SWITCH-OMEGA/dp/B001QG76B8...
Nice idea! I will try to do it until monday if I will find the components and I will tel you if it will work. Thank you vey much!