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| Electronics Discuss radios, chargers, etc... |
Topic Review (Newest First)
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| 11-01-2011 09:23 PM | |
| Cougar429 |
Re: Installing Large Scale Electronics 1st time Generally sliders are less prone to vibrations. If you look at the internals of a rocker switch it is basically a teetering lever with contacts in the middle and one end for a Single Throw, (ON-OFF) or each end, (3-position ON-OFF-ON). When you flip the toggle the spring plunger forces one side or the other of the teeter towards the base/contacts. That sping is the problem as vibrations can actually cause the contacts to lift away from each other. Bad news. In our full size aircraft the switch panel is usually vibration isolated to prevent this sort of thing. The internals of the slider spring tension clamp the double-sided slider contacts onto the fixed contact. Longtitudinal vibrations will wipe the components along each other. Since the slider contacts are either side of the fixed contact, any sideways vibration that would pull one side away forces the other in towards the fixed contact. Less chance of an even momentary break in continuity. The other problem is that toggle switches capable of handling anything over 5A can be quite large and heavy. p.s. The Miracle Switches use toggles. Can't see unless it is vibe isolated how they solve this, unless the toggle activates a slider style base. |
| 11-01-2011 08:27 PM | |
| russ |
Re: Installing Large Scale Electronics 1st time Thanks you've been a big help. Is there any reason why people use slider switches over h/d toggles? *Digi-key does carry some high amperage sliders... http://search.digikey.com/ca/en/prod...937-ND/2055215 but I'd guess it's easier to find toggles locally. |
| 11-01-2011 08:16 PM | |
| Cougar429 |
Re: Installing Large Scale Electronics 1st time Here is a pic of my system basically installed in the Bear. I have yet to fab the switch and remote glow panel. In fact, have yet to figure out where to put it so I can still reach the gear servo and wing bolts  .As you can see the receiver and servo power are separated inside the unit. Luckily I have enough channels on the Rx to allow the power in without having to "T" into a used output to feed the Rx. The servos all plug into the isolator and are fed from either of their power inputs. This is a prebuilt unit that does exactly what I described earlier. However, you can still build a similar system from scratch. The intent is to have battery status indicators by each switch, one 4 cell and the other 5 cell. As it stands I am still trying to figure out if the mount system will be adequate to isolate the two components from vibrations. As you can see the panel is set into 4 grommets removed from a defunct copier. I normally wad everything into foam. |
| 11-01-2011 05:04 PM | |
| Cougar429 |
Re: Installing Large Scale Electronics 1st time When you get up in ESC currents, (I've found 70A and above)you'll notice most of them eliminate the onboard BEC circuitry anyway, so there will be the need for you to provide a separate source for the flight system anyway. Likely this is due to the large amounts of RF noise generated when switching large currents to the motor phases. In that case the ESC is still self-powered by the motor supply pack and all you need to do is send the throttle signal from the receiver. Unfortunately if not kept clean the noise can back trace into the receiver. Same with long servo leads as they act as antennae. As my craft grow larger I have to deal with longer servo leads. So far I have used the noise cancelling extensions and also ferrite rings. The latest on the build table, Rare Bear, will be using a system I bought a while ago. The R4C "Isolator" separates the receiver and servo power sources, allowing one source for the receiver, which in most cases can be a smaller and lighter 5V pack, and one or two sources for the servos. In this case I opted for one larger capacity 6V pack. You can do the same by separating your receiver power and servo power by not sourcing the servos through the receiver. You would need some method to send power to the receiver through the normal plug pin assignments, but tie all the servo power separately. There are several systems out there that do this for you, with the option on some of going straight 2S Lipo as it will have built in voltage regulation. The advantage is the better ones have opto isolation on all the outputs to prevent noise from returning to the receiver from long servo leads. One very important factor is that regardless of number or voltage of your power systems, (this includes your ESC) ALL negative leads must be tied together. This provides a ground reference and path for noise cancellation. NOTE: One thing that is frequently overlooked when working with larger models with a higher flight load, (hence more and better servos) is the power path between source and end use. Most common ON-OFF switches are only rated for a max of 4A and if you try to run all of them directly plugged into the receiver in many cases the internal power feed bus really is not built for high current loads. Hope this makes sense. If not I'll try for a better explanation. |
| 11-01-2011 10:43 AM | |
| russ |
Installing Large Scale Electronics 1st time Thinking ahead to spring time, I'm hoping to have my 1/4 scale J3 cub very nearly done about then. It's going to be an electric powered unit running 9 or 10S (either 2x5s or 3x3s in series). That's the power side of the scheme. On the other side I'll be running 6 HiTec 645MG hi torque servo's (ailerons, elevator, rudder and ahem flaps  ) I would also like to add switched Nav lights, even though I'm committing the sacrilege of adding flaps to a J3!I know that I to isolate my motor, servo & Rx circuits and have redundant power or at least separate power sources for my Rx & servos. So my question is, how the heck do I wire this mess up and keep all the smoke in? |
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