2.4ghz camera interference help please!

I've got this and a helicopter with 3.7v battery.
http://www.amazon.com/gp/product/B000RZUUWG/ref=oh_o01_s00_i02_details

I removed the metal bracket and case of the camera, now it weighs less than a quarter that I was using for ballast.
There was a huge female power plug with 5v regulator built in to convert 9v battery.
It has GND and 2 wires both 5v one to each tiny PCB.
One to the transmitter, one the camera.
Why are there 2 wires with same voltage?
According to ohmmeter they are not connected together in the regulator.

Anyway I cut it off and it works fine with the 3.7v battery in the heli.
Except when the motor is running!
The screen goes almost as bad as snow, black and white horizontal lines.
Even at the slowest motor speed.
I don't think the voltage is the problem, as it doesn't seem to matter if the battery is 10% or 100% charged.
Where do I put the Cap?
It's not just a little interference, it's complete loss of image.
Can I convert 3.7v to 5v? 150ma. Light weight?
I know you guys are good at this stuff.
I would appreciate some help.

The screen goes almost as bad as snow, black and white horizontal lines.

ideas:

  • Maybe the motor is causing EMI ?
    See if a small ferrite bead around the motor power lines and/or camera power lines makes a difference.
  • Shield the camera antenna from the motor chassis.

The video receiver and PC is 20ft away for my test. They are connected by a 10ft cable. Only the video transmitter and R/C receiver is in the heli. The R/C transmitter is 10ft in the other direction. Theses 2 don't seem to interact it's 27mhz. There is no need to shield the antenna cuz it's a transmitter. Have I misunderstood you?

sbright33:
I don't think the voltage is the problem, as it doesn't seem to matter if the battery is 10% or 100% charged.
Where do I put the Cap?

What cap are you talking about? Are you asking about a filtering capacitor? If so, you put it across the voltage supply to your camera and your transmitter. Positive to VCC, negative to ground.
As someone else was saying, it's probably also a good idea to use ferrite beads for your power cables, and run the cables several times through the bead, to choke high-frequency EMI.

Can I convert 3.7v to 5v? 150ma. Light weight?

Yes, you can get a boost mode DC DC converter. With surface mount components, it will be pretty lightweight. You may need a very steady hand and finely tipped soldering iron to get that mounted, though...

Theses 2 don't seem to interact it's 27mhz.

Interference from the motor in operation could appear on the power line as EMI or in the modulated transmission as RFI.

3.7V is borderline for the transmitter to operate, its designed for 5 volts. the camera isn't going to be real keen on 3.7V either. The rotor motor is going to cause voltage dips on regular intervals related to speed likely to levels below 3.3V. Operating vid equipment off of the flight power is a bad idea. The camera is trivial compared to maintaining flight control. Power vid off of its own source.

I think you are right. The ferrite beads didn't make a bit of difference. Tried a 3300uf & 6600uf Cap. Tried a filter Cap in 3 different places. Absolutely no change. I don't understand what is going on. When I measure the voltage on the Cap it doesn't change when the motor is spinning slowly. The interference is complete and total. Doesn't matter whether the motor is slow or full 100%. Can't see much noise with a scope.

I'm going to give up and try a different approach. Not because maintaining flight control is more important. It is not. When I lose power the copter drops softly to the ground.

I have a small lithium thionyl chloride battery 1.2Ah. Is there any alternative that is small and cheap?

I tried 1/2 a 9v battery 4.8v. Seemed small enough. Works great! No interference, of course. But that little bit of weight makes it fly less stable. Back to the drawing board. Will a DC-DC converter solve the noise problem?

Can anyone recommend a small DC-DC chip?
Well only if you think it will work, so I can avoid using the expensive battery.
Like this?
http://www.solarbotics.net/library/datasheets/LT1111.pdf
Any alternatives?

How heavy is too heavy? Can you add a second LiPo battery?
http://www.dealextreme.com/p/900mah-lithium-polymer-battery-for-e-sky-lama-v3-v4-lipo-10783 (43 grams)
There are other batteries, too. Li-ion or Li-poly, or even older technologies like Ni-MH.

1/2 a 9v battery is too heavy, even without the metal case.
This is better:

But it's expensive, not rechargeable, and only 3.6v.
It seems to work at first, but not sure for how long as the voltage goes down.
I want lighter! It's a small copter. Do you think the DC-DC will remove the noise?

I can't believe your link weighs 43g. I can read it says that. My Saft is 43g.
Must be much more dense, it's tiny.
1/2 9v is 90g.

Your issue isn't noise but undevoltage, the dc-dc converter will get whatever source you choose to a solid 5.0V for your gear.

Is there any alternative to the chip I mentioned?
1/2 of the 7.4v Lipo is 22g? Can anyone verify this is possible?
The battery in my plane runs for 5 hours powering the camera until I gave up waiting.

3 Series connected 1N4000 diodes will shave around 2.1V from the power supply taking the 7.4 to 5.3 which could feed the camera and transmitter directly.

Yes, but 1/3 of the power is wasted in the diodes.
Can't I add 1/6th of a standard 9v battery to the 3.7v battery in the copter in series?
Obviously it would continue to provide power to the motors.
Measuring them under load it should be 5.2v. Why not?
Let me try it...

At 5.2v the camera does not work! I've got a strong signal, a black screen. Turning on the motor does not change the black screen, so that's good news. 0.3v = 150ma x 2 ohms. Back in a flash!

At 5V I get the same results as without the 1/6th 9v battery + 2 ohms. As soon as I turn on the motor with the stick on the transmitter it's complete snow. It can't be that sensitive to voltage, or I'd have to retune it every minute as the battery is used. There's a dial on the video receiver. No retuning is needed with a 3.7v battery. Even after hours, without the motor running. Let me see if it runs on 3.4v. If so I know what to do!

It runs on 3.3v, no re-tuning of the receiver needed as it goes down from 5v. So I'm going to use the 3.6v Saft battery. Then I will try a resistor between them to increase the life of it. Ideas?

Looks like you are going to have to power seperate from the flightpack.

sbright33:
It runs on 3.3v, no re-tuning of the receiver needed as it goes down from 5v. So I'm going to use the 3.6v Saft battery. Then I will try a resistor between them to increase the life of it. Ideas?

Put the video camera/transmitter close to the helicopter, with its own power. See if it works when the motor is on.
If it doesn't, then move the camera/transmitter away from the helicopter and try again. How far do you need to move it before it works?
It may very well be that the camera transmitter simply is drowned out by EMI from the motor. If that's the case, you have a much harder engineering challenge to solve.

It even works at 3.00V! Unfortunately that's the loaded voltage of the Saft battery after 5 minutes...
It works IN the helicopter just fine with 1/2 a 9v battery. I even got it off the ground. But it's a little bit heavy.
I'm going to search for batteries online...

Nokia BL-5C is only $3 on Ebay. 23 grams. 3.7V. Can't beat it for the price.
It seems to me that Ebay can solve most engineering problems for us!

How can that weight be correct? I have a bunch of tiny cell phone batteries around the house, and they all weigh at least 100g, most of them 120g. I guess mine are not Li-ion? Just looked they are. How can this one be so light, with the same capacity in mAh? For $3? Is it a typo? Anyone know? How do they do that? When none of the other brands are as light?