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Anyone know how would be the best way to use the featherweight magnetic switch with an arts 2 in dual battery mode?
Magnetic switch and arts 2
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SRBell
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Really? I just got a Raven II and the same switch. That's a pretty big V drop. I can't verify the specs being there's no instructions for it. I'll test the voltage under load tomorrow. BTW, talk about small surface mount parts! Before actually receiving the units I thought I'd wire in some external led's to the AV bay... I can barely see the led's on the board with really strong reading glasses lol. Good luck soldering that. That's too bad, I really like all those blinky lights!
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Here we go...
From the release, when the switch was announced...
When an ARTS is used in dual battery mode, are the batteries in series, or are they wired to separate circuits? If so, do you need to switch both batteries, or just one of them?
If they're wired in series, then 18V is too much for the switch.
-Kevin
From the release, when the switch was announced...
When an ARTS is used in dual battery mode, are the batteries in series, or are they wired to separate circuits? If so, do you need to switch both batteries, or just one of them?
If they're wired in series, then 18V is too much for the switch.
-Kevin
ClayD
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Troj, the arts2 has a pyro circuit and and logic circuit. they are seperate to my knowlege.
you can run the switch on any battery, but the output voltage is what matters, Adrian told me a while back what it was and I cant remember. Made me think it may have issues...
I think a better number for the arts2 was 7.74, or 7.4 and i cant remember what Eric told me there either... i have it in an email...
If you were to use the swicth with an arts 2, My opinion is that it should use the Switch Ports... Not inline with the battery, that way if it is designed to disconnect the pyro charges, and the logic circuit,, your not inadvertantly powering them by bridging these ports.!!!!!
BUT if the release says ANY altimeter,, its as Advertised... i may change my mind and get some...
you can run the switch on any battery, but the output voltage is what matters, Adrian told me a while back what it was and I cant remember. Made me think it may have issues...
I think a better number for the arts2 was 7.74, or 7.4 and i cant remember what Eric told me there either... i have it in an email...
If you were to use the swicth with an arts 2, My opinion is that it should use the Switch Ports... Not inline with the battery, that way if it is designed to disconnect the pyro charges, and the logic circuit,, your not inadvertantly powering them by bridging these ports.!!!!!
BUT if the release says ANY altimeter,, its as Advertised... i may change my mind and get some...
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Okay, there's an easy answer...
Hook a multimeter inline with where you plan to place the switch, with the ARTS connected the way you plan to use it, and see what the meter tells you is going through the circuit.
-Kevin
Hook a multimeter inline with where you plan to place the switch, with the ARTS connected the way you plan to use it, and see what the meter tells you is going through the circuit.
-Kevin
The output is whatever the input is, minus a very small voltage drop. The FET switch used in the magnetic switch has an on-resistance of less than 20 mOhms. So if you're sending 3 Amps through your ignitor, you would only be dropping 0.06 Volts across the switch, or less.
You can connect up a larger LED + series resistor between the output and ground if you want, all Radio Shack parts. That's the way the LED on the switch is hooked up already. Just start with the voltage of the battery, subtract off the forward voltage drop of the LED, and you have the voltage you'll want to drop across your resistor. If that difference is 5 V and you want 10 mA current, then you would need a 5V/.01 = 500 Ohm resistor.
No issues with the end product. The design took a while to iterate on, is all.
You can use a magnetic switch in place of any other switch that you would put on the high side of the circuit, as long as the battery voltage is 16V or less, and you're not planning to put more than 12 Amps continuous or 20 Amps for 1 second through the switch. That's already many times the capacity of what the bulky key switches are rated to handle, current-wise. Those are usually 4 Amps or 6 Amps.
I can attest to the greatness of Adrian's magnetic switches.
I've already installed two; one in a minimum diameter carbon fiber rocket, and one in an oddroc. Both would have been very difficult to install traditional switches.
The switch itself is TINY, although I am happy to report Adrian decided to make it compatible with 4-40 screws rather than the raven's 2-56 only which makes it easy to pick up mounting hardware at your local home depot, or ace hardware.
Mounting was super simple, and you don't really need instructions as the in, out and ground are all silk-screened onto the pcb.
My ONLY complaint is the first switch I installed turned out to be bad (I will be returning it soon). I didn't know it was bad because I didn't know the "normal" behavior of the switch, and it took me a while before I started swapping out parts to realize the first one wasn't working properly (turned on immediately upon putting the battery in)
This particular switch is powering a brand new piece of electronics from missileworks - the WRC+ !
Here's a sneak peek:
So far, Jim Amos's WRC+ it's on the "completely awesome, what did I do without it" list along with the magnetic switches.
Before you say something, I know... it's a bit dangerous connecting up a just released product to another product that's still in beta, but if I had to install a traditional power switch, I'm not sure I could even test right now.
I've already installed two; one in a minimum diameter carbon fiber rocket, and one in an oddroc. Both would have been very difficult to install traditional switches.
The switch itself is TINY, although I am happy to report Adrian decided to make it compatible with 4-40 screws rather than the raven's 2-56 only which makes it easy to pick up mounting hardware at your local home depot, or ace hardware.
Mounting was super simple, and you don't really need instructions as the in, out and ground are all silk-screened onto the pcb.
My ONLY complaint is the first switch I installed turned out to be bad (I will be returning it soon). I didn't know it was bad because I didn't know the "normal" behavior of the switch, and it took me a while before I started swapping out parts to realize the first one wasn't working properly (turned on immediately upon putting the battery in)
This particular switch is powering a brand new piece of electronics from missileworks - the WRC+ !
Here's a sneak peek:
So far, Jim Amos's WRC+ it's on the "completely awesome, what did I do without it" list along with the magnetic switches.
Before you say something, I know... it's a bit dangerous connecting up a just released product to another product that's still in beta, but if I had to install a traditional power switch, I'm not sure I could even test right now.
Thanks, Alex!
Starting out in the "on" position when you plug the battery in is normal. Does it fail to turn off with the magnet?
Sorry, should have been clearer - switch seems to be stuck in the on position. Magnet has no effect on the switch.
Sorry to hear that. I'll ship you another. A bad one must have slipped past the tests I do on each one before I ship.
-Adrian
atxcple
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in single and dual battery mode the arts2 still only uses one switch so to keep with their design just sodder your switch leads that you put into the screw terminals to the featherweight magnetic switch.
ClayD
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have you done that?
That is why i shy'd away... the arts2 requires 7.(something - around 4) volts to operate. the Switch ports are "after" the voltage regulator, so if the magnetic switch causes a 7.7 regulated volts to drop to 7.1, you could be on the edge of brown out...
(i measured everything when the inital word came out, my numbers may be off a tadd...
AdrianA said:
This means, connecting the magnetic swich to the battery, then... you would have to "jumper the switch ports".. In single battery with the jumper to the pyro channel, you may be okay(although i dont recomend that operation..), Maybe if your using something like an 11.1volt 850mah lipo.. Dual battery mode, may be draining your pyro battery by "jumpering the switch ports", even though your not "arming your altimeter" the pyro channel may think its armed.
A couple of comments here...
First off, thank you Adrian - as usual, fantastic customer service. I'll send back the old one so you can figure out what may have happened.
Here are a few measurements I just took from my switch setup you can see in the photo above.
All testing was done using an energizer 9 volt lithium battery - if you take the battery apart, it uses three 3.2v batteries connected in series.
I used a HP 34401A bench multimeter which is pretty darn accurate.
Voltage of the energizer battery connected directly to the multimeter: 9.613
Voltage from the altimeter side of the magnetic switch after connecting the same battery: 9.610
Voltage and amperage from pyro 0 terminal when I simulated a .1 ohm load (basically shorting the battery): 9.34 volts, 12.31 amps
hope this helps someone.
First off, thank you Adrian - as usual, fantastic customer service. I'll send back the old one so you can figure out what may have happened.
Here are a few measurements I just took from my switch setup you can see in the photo above.
All testing was done using an energizer 9 volt lithium battery - if you take the battery apart, it uses three 3.2v batteries connected in series.
I used a HP 34401A bench multimeter which is pretty darn accurate.
Voltage of the energizer battery connected directly to the multimeter: 9.613
Voltage from the altimeter side of the magnetic switch after connecting the same battery: 9.610
Voltage and amperage from pyro 0 terminal when I simulated a .1 ohm load (basically shorting the battery): 9.34 volts, 12.31 amps
hope this helps someone.
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This would be cool. Maybe we can meet at LDRS and let me check out how you wired it. I am Chris' Rocket Supplies so I will be there the whole time, after I fly my O motor on Thursday.
When you measured the 12 Amps, was the measured voltage simultaneous with that, and if so, where did you measure it?
Thanks.
Are you coming to LDRS? We could meet up there.
Yes, I'll be at LDRS - I'll bring the switch.
The Voltage and Amperage were measured simultaneously using probes on the wrc+'s pyro1 output, so the voltage drop is a combination of the switch and the wrc+. While my multimeter can record a few probes at the same time, I only have one set, so I couldn't measure the voltage at the battery, or just after the magnetic switch - this was an eBay special
I can guarantee the majority of the voltage drop was due to the WRC+ MOSFET, as the decrease correlates pretty well with the MOSFET's ON-state Drain-to-Source Resistance of this particular part.
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