Power Safe for any receiver

[Mike Blandford]

Try these (should be available with different number of connections) **LINK**

Preci-Dip part 801-87-036-10-001101 is a 36 way version where you may "snap off" however many connectors you need. Clearly, these may be available from elsewhere (found them at Digikey as well as Farnell).

I measured the (square) pins on a FrSky Rx (X8R) as 0.6mm (digital caliper), and the pdf file for these shows 0.635 as the square pin size that fits. For round pins it shows 0.7mm to 0.9mm. 0.635mm square is 0.898mm across the diagonal, so I reckon a 0.5mm square pin (diagonal 0.7mm) would also fit, so should be fine for 0.6mm.

Mike

Edited By Mike Blandford on 19/08/2018 13:19:35

[Ron Gray]

The Ultra guard has an optional remote LED which flashes when it’s in operation, depending on where it is mounted, this can be seen from the ground. Personally I don’t use it on mine, yet, but am thinking of getting a couple for my 2 Ultra Guards. It really is a clever device as it detects the power being supplied to the Rx then sets itself at .5v less, when it detects a fail it cuts in immediately. It also charges itself from the main Rx pack when in flight.

I made the mistake of not fitting one to my GP Revolver which was completely destroyed as a result of a power switch / cable failure which cut the Rx power. This would have been saved if I had an Ultra Guard fitted.

[Chris Bott - Moderator]

Thanks Mike, I'd found a short looking connector that looks something like those, but I hdn't seen the tall ones. Those are much more likely to be suitable.

Ron I do wonder if a small percentage of failures attributed to switch / cable failures might be a fault at the plug that plugs into the Rx?

So - here's another permutation. After knocking this 6ch one up I realise that for 3 of the receivers I plugged it into, it would have been better if I'd included 7 ports.

I think this style would be easier / neater to encase?

The Orange receiver ends up upside-down! DOH!

[Chris Bott - Moderator]

The latest incarnation. Using better quality sockets as discussed.

This is an 8 way. It could easily have one or two sockets removed to suit the Rx.

I'll probably cut the one end off and also make a straight through version. Then we're ready to look at cases.

I don't think I'll be going into production, they're pretty fiddly to put together and take time.

[Gary Manuel]

What's the current rating of the PCB tracks Chris?

P.S. I think the straight through version is more practical than the right angle one, but it's good that you have both options.

P.P.S. When you get the gremlins sorted, I'm sure you could sell just the PCB's (and cases?) as most hobbyists (including me) would be interested in making them up from the components.

[Chris Bott - Moderator]

To be honest Gary the tracks are just as fat as I could make them. There are tracks both sides of both boards so 4 in total per rail.
My thoughts on their rating is that if we have a model which has servos where that would be a worry, then we should be using something a bit more sophisticated anyway.

I guess some copper wire could always be soldered along them.

PM your address to me and I'll pop a board in the post.

[Gary Manuel]

PM sent Chris.

[Stephen Jones]

What a most excellent idea and design you have their Chris.

And i am sure you are right in regards to possible power drops to the Rx via the standard servo power connector.

As i my self have had problems in the past with green corrosion on the power connector.

Steve.

[Mike T]

Posted by Chris Bott - Moderator on 21/08/2018 22:33:49:

I don't think I'll be going into production, they're pretty fiddly to put together and take time.

But if you (or someone) could put the boards, headers and plugs in a polybag with an A4 'how to' sheet, I'm sure there'd be lots of takers - assuming you could do it for, say under 10 quid?

Edited By Mike T on 22/08/2018 01:20:01

[Chris Bott - Moderator]

Thanks Mike.
That's certainly something to think about.

[Chris Bott - Moderator]

I still haven't flown with one of these, but that's only because I haven't been flying for months.

I am part way through putting together an ARTF that I think would benefit.
Having decided that two separate supplies would suit this model, I've developed the idea a little and added a dual 10A diode and an LED indicator for each supply.

I'll probably use a UBEC one side and a LiFe battery the other. I might cover all the exposed parts with hot gun glue or Sugru. The board can be screwed down in the model with the Rx mounted on velcro or ty-wrapped down. I've only just realised that I could even remove the Rx from the model and still leave all the servo wiring intact.

[Martin McIntosh]

Anyone want a Spektrum Powersafe 9ch Rx? I bought one some time ago but have not even powered it up. I have, however, pinched all the satellites.

[Geoff S]

Posted by supertigrefan on 19/08/2018 10:15:36:

I am not particularly electronics savvy and I get the issue that is being addressed here but isn't it a bit like the multi-socket cubes we used to use to plug a bunch of plugs into a single outlet or using a 13A device on a 3A circuit?

Used to? We still use them but I'm careful of the load so I don't plug 2 x 3kw (ie 13 amp) devices into the same one. They're just a convenience to save swapping low energy devices for each use. I'm just annoyed with myself for not building more sockets in when I wired the kitchen ring main - my excuse is that I had to work fast one evening after work because the kitchen fitters were plastering the following morning.

I've often thought the main sticking point in servo load wasn't so much the connector but the receiver PC track. Perhaps it's better to use a separate battery/ubec and only let the receiver itself carry the signal loads. I've only done that with retracts.

Geoff

[Chris Bott - Moderator]

That's just what this is doing too, Geoff.
Power from the diodes goes direct to the servo sockets rather than via the Rx.

[Geoff S]

Sorry Chris, I hadn't appreciated that. I'd just prefer a circuit diagram rather than a description - I understand them I'm a bit slow these days - it's the weather.

Geoff

[Andy Meade]

Chris - any closer to releasing these at all? I'm at a point now that I could do with a couple for projects nearing completion

[Chris Bott - Moderator]

Wow - I didn't realise it had been close to a year since I updated this thread. I've been developing this unit, on and off for a while haven't I?

So - bringing things right up to date:-

To recap - this unit takes two separate Rx supplies (2 batteries, a UBEC and a battery or two UBECs) via decent connectors and combines them via two schottky diodes thus giving supply redundancy.
This supply is then applied using a wide PCB track, doubled up on either side of the PCB, directly to all the servo ports (not via the Rx tracks).
The supply also feeds the receiver (via two routes for redundancy) and the servo outputs are routed to the servo ports.
I've now included FrSky S.Port telemetry to the PCB but this can easily be omitted.

The big limitiation now are the diodes. Because of the volts drop across them and the servo current through them, these do dissipate some power. So they can get warm or even overheat if servo currents are too high.

I now fly this unit in a Segull Chipmunk. In this model an FrSky Neuron ESC provides a UBEC supply and a 2S LiFe provides a backup. I call this the backup supply becasue I've set the UBEC supply to a slightly higher voltage than the battery. Therefore the UBEC supplies all the power. The idea is that if this fails, the battery will take over. The radio is set up to warn me with voice alarms if either supply is lower than it should be.

It's quite amusing to disconnect the LiPo from the ESC, which obviously removes the UBEC supply, and hear "Warning - Systems are on backup power ".

A 3d Printed box makes for a neat installation and two LEDs show the status of each supply.

[Chris Bott - Moderator]

PS Here's a shot of the one installed in the Chippy.

One unexpected feature is that the Rx can be popped out easily without disturbing any of the wiring at all.

[PeterF]

Looks good. I have been making my own back up power system with Schottky diodes, nowhere near as nicely turned out as this, kudos to you. I use 40Amp rated diodes on each supply to give some overhead, reduces the voltage drop somewhat and provides a bigger package for heat dissipation.

[Corne De Wagenaar]

Hi Chris, thank you for your help. It looks fantastic. Might not work on the Extra, but I have a Cessna and a few smaller electrics where it will work. I will keep everyone posted on how it works.

Regards

Corné