5 volt USB power for Ipad charging noise on radio

[Greg_Oz]

I'm using an Ipad to run Oz Runways.The battery lasts well but on longer trips I have to remember to charge it every night. When charging I get annoying bursts of static on the VHF radio. I've tried various USB power sources and toroid coils on cables but unable to eliminate the problem. It even occurs when running off my backup quick-start battery that's not connected to the aircraft power.

 

Has anyone else had this problem and found a solution?

 

 

[Geoff_H]

Tried wrapping your device in foil? Best to earth the foil. Without actually seeing the situation I am guessing that it is noise from the switch mode power supply, probably very cheap and lots of side frequencies.

 

 

[lyle janke]

Tried wrapping your device in foil? Best to earth the foil. Without actually seeing the situation I am guessing that it is noise from the switch mode power supply, probably very cheap and lots of side frequencies.

hi i have exactly the same problem it is exactly as suggested . but getting a port that doesn`t generate noise & will charge an ipad is nigh impossible (apple need special port specs to charge )so if someone could build a powered -port for i-pad they would have a winner

 

lyle

 

 

[Geoff_H]

You can buy integrated circuits that will control 5VDC. They have over current and over voltage protection. The noise may also come from the cable acting as an antenna, shield the cable with foil and earth one end only, this is very important.

 

 

[cscotthendry]

If you have a cigarette lighter socket in your plane, you could try replacing it with one of these.

 

Twin USB Panel or Surface Mount Outlet 5V 3.1A | Jaycar Electronics

 

I put one in my plane and I have had no interference with the radio from it.

 

Even if you don't have a lighter socket, this unit comes with a mounting adapter to mount it under the panel.

 

I would also suggest that you run the power and ground wires for it, right back to your distribution bus, rather than to a nearby instrument or whatever.

 

 

[jetjr]

There is aviation grade ones but at $300 usd are a bit hard to afford

 

Ive tried many plug in and panel mount adapters and have the same problem, its simply cheap electronics

 

I have a couple of the Jaycar ones but not in the plane, might try it. Not all of them work with Ipad though.

 

Not having Ipad on charge seems to see it run much hotter so charging is important.

 

I use a high quality usb back up battery pack now. The charge circuits are smart enough to effectively use it first then revert back to internal capacity after.

 

 

[Downunder]

Stein Air list a couple on their web site. No idea how effective these units, are but they are an aviation related company.

 

You searched for Usb - Steinair Inc.

 

 

[frank marriott]

I have found the noise is generated from the iPad itself (plug in an external battery with same results).

 

Particularly after the iPad battery is low, and produces greater interference on 126.7 than other frequencies.

 

Mine is an old iPad and a mate with the latest iPad does not have the same problem.

 

Make of that what you like.

 

 

[lyle janke]

You can buy integrated circuits that will control 5VDC. They have over current and over voltage protection. The noise may also come from the cable acting as an antenna, shield the cable with foil and earth one end only, this is very important.

hiyou need to get an alt supply from using switch -mode this is where the electrical noise is being generated & impossible to regulate , also a std usb port will not neccessarily charge an apple correctly it needs to be an apple savvy port

 

lyle

 

 

[Kyle Communications]

The apple savvy is just different charge rates for phones and Ipads. It is just 2 resistors in the USB lead. Most noise is generated in the crappy 12v to 5V converter you are using as they are switch mode . If you want to do it properly you need a proper linear regulator to do it. BUT they will be much larger and also have to have a heatsink..so it depends on what your happy to live with

 

 

[Blueadventures]

I'm using an Ipad to run Oz Runways.The battery lasts well but on longer trips I have to remember to charge it every night. When charging I get annoying bursts of static on the VHF radio. I've tried various USB power sources and toroid coils on cables but unable to eliminate the problem. It even occurs when running off my backup quick-start battery that's not connected to the aircraft power.Has anyone else had this problem and found a solution?

I've got a Jaycar double usb 1amp/ 2.1 amp in my panel; when my samsung tablet is on charge I get noise from time to time. When I hear the noise I remove the usb from the Jaycar socket and the noise stops; I then reinsert the usb. This works to cancel the noise. I find the noise most frequent when tablet is below 10%.

 

 

[Guest TAA GregW]

Thanks for all the tips.

 

I'm using the Jaycar USB at present. Wrapping the converter (currently loose) and cables in foil does have some effect but not guaranteed to stop static on the radio.

 

Using shielded cable with one end earthed may well help - I'll try it if I can find a shielded usb cable.

 

I was hoping to find a shielded Ipad cover but no luck as yet. Has anyone found one of these?

 

Cheers,

 

Greg.

 

 

[skippydiesel]

It sound like I am gloating - I have no radio interference from three plug in systems changing at all times - GPS, GPS antenna, iPad mini & from time to time, I also charge my phone and emergency back up transceiver.

 

In my supreme ignorance I have just used auto accessory twin cigarette lighter ports mounted behind the panel,for my permanents (one spare).I have an additional single cigaret lighter port on the panel for occasional inflight use (phone/ transceiver).

 

The GPS systems have their own 12 V chargers plugged in, the iPad supplied charger did not keep up with OzRunways power demand, so I found one that would (works like a charm & I don't have to worry about being charged 100% before I fly).

 

All power outlets are separately fused & further guarded by my aircraft circuit breaker system.

 

I have a fair bit of experience with 12 automotive but almost nothing with aircraft systems. One thing I did, which may help with reducing stray power causing interference, was to make sure that every electrical component is very well earthed back to the battery & engine casing. I also avoided wherever possible creating a coil in my wiring, as I have heard that the electromagnetic waves produced can interfere with radio & other sensitive components.

 

In the end I suspect that I have just been lucky.

 

 

[Kyle Communications]

This is a good explanation of the apple charging

 

Apple and other USB charger secrets |

 

Also if you want to make a non switchmode charger then its extremely easy nowadays. Just use a LM338 TO-3 package and 2 resistors R1 and R2 in the diagram to set the voltage. fit the capacitors just for interference and parasitics Mount the device on a large heatsink and fit a USB connector. Dont worry about the transistor or the 1K resistor

 

The big issue with a linear converter is the power you waste. at 14V input and you want 5 V out you are dropping 9V and if you were drawing 2 amps at the 5V you would be wasting 18 watts of power and it goes in heat this is why you need the large heatsink. Yet yu are only consuming 10 watts doing the charging. Switch modes do this very well and with literally no heat so far more efficient but they are dirty filthy things because they run a high frequency oscillator. Trying to clean one up and shielding it is the main trouble and for the consumer market and price...no one seems to care about it :)

 

 

 

[aj_richo]

This has come a few times in the past, someone else put me on to one of these:

 

I recommend a Vority Dual USB car charger from Amazon. 3.1A and 1A outlets.

 

It will charge my mini iPad and iphone together

 

and most importantly, NO radio interference on the MGL v6 when charging.

 

Oooh bugger - currently unavailable

 

Amazon.com: Vority Dual USB Car Charger 3.1Amp 15.5W (White) 1.0+2.1A Universal Ports, Smart Power Supply For iPad Mini /4/3/2, iPhone 5S/5C/5/4S/4/3, Android / Blackberry / Windows Cell Phones & Tablets, Portable Cigarette Lighter Adaptor, Mobile Travel Charging Station 12V Input - 5V Output. Fast & Smart Duo31CC: Cell Phones & Accessories

 

 

[Doug Evans]

I use one of these with no problems no noises got it of eBay. Works a treat

 

 

 

 

[snarf007]

I remember seeing a similar thread on Vansairforce and it is pure luck if you find a non-aviation unit that does not create noise. Steinair buys a cheap switching unit and do their own modification to it. The $20 question is what modifications do they do?

 

 

[Geoff_H]

They probably use capacitors and inductors to isolate the noise, then to prevent radiation directly place a conductive shield rather to the aircraft earth. Also shielding the cable, again earthed to the aircraft earth, to prevent the cable being an aerial to the electronic device connected that self contains radiation.

 

 

[skippydiesel]

.........................................................................................................................In the end I suspect that I have just been lucky.

I lied - I am gloating & I dont really think I have just been lucky - whatever happened to the KISS PRINCIPLE - It is not conceivable that I have 5 power ports, three items on charge at all times and a fourth when required and no radio interference, just by luck.

I may not be fully "up to speed" with all of the fandangled suggestions, made above, that I am sure all work very well but sound either costly and/or difficult.

 

My transceivers/transmitters all have shielded cable, where required and all units are well connected back into the earth/negative circuit. Aerials/antenna are located with due regard to recommended distances/clearances and have generous ground plaines.

 

Just by being careful with my connections, keeping my cable runs as short/neat as possible and making sure everything is well earthed has worked for me, every time (aircraft and land bound vehicle).

 

 

[robinsm]

Wire in a 12V cigarette lighter into the dash then use the usb charger for your Ipad etc. Never has a problen in 5 years.

 

 

[seb7701]

I recently installed an accessory plug in my dash and noticed that the iPad/iphone certainly brought noise into the radio, not from the charger but only when you connect the actual device to the charger and start shifting some current. I emailed Rainier from MGL (I have an MGL V10 radio in the Jab) and received the following rather logical response. As a result, I now have a couple of 7805 regulators and am going to experiment with them on an iPhone charger.

 

Here's what was said-

 

This is a well known issue with phone chargers - they are switched mode regulated supplies to make them small and this causes wide-band radiation. It has nothing to do with shielding of the V10 - your charger is actually transmitting a signal wide band that is picked up by your antenna. Proof ? Simply disconnect the antenna and things go quiet...

 

Your V10 cannot do anything about it - it looks just like a valid VHF transmission.

 

 

 

The only solution is to use a charger made with a linear regulator (you just need a simple 5V linear regulator such as a 7805 to provide the 5V on the USB plug).

 

 

 

Rainier

 

 

[RecComGarry]

What we have here is:

 

DC-DC converter from ~12v to 5v. Another DC-DC in the IPad charging the battery. Modern DC-DC have gone up a lot in frequency to minimise loss and size. Also to get the frequencies away from AM radio frequencies. Right up to the frequencies used for aircraft comms. Also remember aircraft comms is also AM. Things are not going well here. Now we want to place the USB charger right next to the radio, along with the IPad. Also prop close to the antenna. Things are getting worse, not better here! What to do.

 

1. Is it the USB charger, or the IPad. Get a long USB cable and get the IPad away from the radio and antenna. If the noise stays, it most likely the USB charger. Plenty of advise in other posts about that. But also you might consider wiring for the USB charger to be much further from the radio. If it's the IPad, you may gain from moving it away from the radio.

 

2.Terminate the radio cable, at the antenna, with a 50 ohm load. If you still have the noise, you have a crappy radio, or cable, or installation. You need to fix that. That probability will also fix your general radio comm problems!

 

3. If the problem goes away with the antenna termination, then the noise is getting into the antenna. If you can't fix the noise at the source, then consider reposting the antenna further from the cockpit.

 

4. I usually also advise a sacrifice to the GODS here, as most interference issues don't seem to have a rational cause. However that tends to be frowned upon these days.

 

 

[RecComGarry]

For those looking for a deeper understanding, have a look at:

 

http://k9yc.com/KillingReceiveNoise.pdf

 

 

[Kyle Communications]

Seb

 

Not that simple really...be prepared to use a large heatsink. There are calculations for what size you will need depending on the quality of the heatsink and also the junction temperatures of the regulator. Your running the engine so your input will be around 14V and you are regulating down to 5V so you are dropping 9volts across the regulator. If you are drawing 1 amp into the device you are charging thats 9 watts of power being dissappated in heat. You need to keep the regulators junction temperature to a point that it will not fail buy the size and efficiency of the heatsink

 

 

[Kyle Communications]

Most 7805 are only good for about 1 amp really in a TO-220 pack...I use the LM338 in the TO-3 pack its good for 5 amps and can dissapate more heat just you need 2 resistors to set the output voltage