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Terry

Airwave 633

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Can we have some layouts and pictures here of the way you have used your 633 modules please. It seems a shame that it runs on 3.3v, the old problem of a 12v camera and a 5v Tx has been replaced by a 5v camera and a 3.3v TX :(

What we need now is a 3.3v camera and we are back to where we were :P

We would also only need one LiPo :rolleyes:

Terry

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Actually, I like the 3.3V operation. A simple 3.3V LDO linear Vreg is all that is required (and the Vreg will not run insanely hot on 5V). In my case, I'm using a switcher Vreg with good success, but it did take a bit of filtering to tame the noise.

post-6-1186937247_thumb.jpg

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I haven´t tried yet but I was thinking on powering from a 1S Lipo and a diode, or a 1S and a linear reg to 3.3V.I have here one LD1024-33. I don´t like switch regulator because the noise.

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Thanks guys keep um comming. I was thinking of using 2 linear regs, 1 5v and 1 3.3v off 2 LiPo but I'm still at the thinking stage :)

Terry

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Mine is still working good with 1 (1400) lipo (3.0-4.1vdc) and a resistor. I used a resistor value to drop to 3.3 going into the transmitter on a fresh charge and charge often. I haven't noticed any range problems and the rig runs cool.

B)

I've checked the transmitter with a lipo voltage of 3.0vdc and it seems to process the video signal just fine, my GUESS is that it will work with a input voltage range from 3.3 down to 2.2 and all that is lost is full RF power at less than 3.3vdc.

I am flying at 2 miles or less so I don't see any range loss (I've never seen the transmitter at less than WALL to WALL when powered). I most often fly 2 or 3 times (10min flights) then charge the transmitter batt with my field charger.

Edited by ddwaner

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Thanks for your post, what resistor are you using ?

How are you getting your 5v for the camera ?

Terry

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I used a LM 2575 with a 330uH choke and a 330 uF capacitor on the output stage. Pretty much the same as datashet said, this kind of filter doesn´t eliminate at all peaks, I´m having around 0.124 VPK-PK, did try it at the field and didn´t like it at all, got some noise that I don´t like. So finally I changed it for a linear LD1024-33 getting now 0.034VPK-PK that is quite acceptable, haven´t tried at the field though but running all my video electronics for 1 hour long without a problem (I´ve noticed my 5V linear reg runs hotter now)

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Wavess, Linear Regs regulate faster than switching regs. Due to the fact that spikes and peaks have a high slew rate and high frequency components, the linear reg will always perform better in terms of "filtering". However, it doesn't eliminate all noise, so in my tests I added a coil in series to the input of the linear reg and a 470uF Low ESR capacitor in parallel, and make sure it's definitely a Low ESR type. I never payed much attention to this until I tried them and saw what a big difference they make!

Performs very well. You can increase the coil's and the cap's values to whatever your plane can carry :-)

It's a compromise between performance and size/weight.

Mr.RC-Cam, I would be very interested to see how you did the filtering on your switching reg, I'm always experimenting with this.

Edited by Hartwig

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by the way did you see farnell is startinng to sell airwave modules !

go here and see more in the modules section :

http://export.farnell.com/jsp/bespoke/besp...reless/home.jsp

oh no Airware modules if you enter as located in the US

aha maybe only sold in europe ?

but anyway have a look and all the wireless stuff

see here:

http://dk.farnell.com/images/en_UK/pdf/Sel...pt_DK_01_42.pdf

and:

http://dk.farnell.com/images/en_UK/pdf/Sel...pt_DK_43_84.pdf

see on page 10

oh it works fine with the UK version of farnell:

http://uk.farnell.com/jsp/Electrical/RF+Co...requestid=30319

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Wavess, Linear Regs regulate faster than switching regs. Due to the fact that spikes and peaks have a high slew rate and high frequency components, the linear reg will always perform better in terms of "filtering". However, it doesn't eliminate all noise, so in my tests I added a coil in series to the input of the linear reg and a 470uF Low ESR capacitor in parallel, and make sure it's definitely a Low ESR type. I never payed much attention to this until I tried them and saw what a big difference they make!

Performs very well. You can increase the coil's and the cap's values to whatever your plane can carry :-)

It's a compromise between performance and size/weight.

Mr.RC-Cam, I would be very interested to see how you did the filtering on your switching reg, I'm always experimenting with this.

I knew switcher reg has to be filtered, it´s way more efficient than linears but right now I don´t have time to try diferent combinations of coils and chokes, and don´t want to add any more weight on my plane, it has passed by long its optimal weight. But that´s a good advice Hartwig and would try someday

I´m too interested in seeing how you guys handle with switchers, or it´s a secret stuff? This topic´s question has not been answered clearly yet

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each power supply solution needs to be revised carefully,

cost, size, weight, loss, noise, heatsink, easy of design, skils.

when all prarameters are sorted after importance factors,

you can start to look for solutions/design it.

switchers and lenear are used often, even in a mix,

both types have their goods and bads,

with skils each bad can be changed into acceptable.

the "bad" for switchers is often noise, this can be handled with the right kind of filter components, even pcb layout must be carefully

designed so the current flows go where you want it to go.

filter components add size and weight, but in the end still much smaller (and even cheaper) solution compared to a linear with a heatsink the size needed to handle the power, maybe so in some cases !

201stepup.jpg

switchers can be made in almost anysize, I have designed them proffecionally for many years, from 1W to 800W, and from any volt to any volt :-)

See this picture, the two extra coils and the two extra capacitors, are the input and output filter, they only add 2% extra loss, the total converter have 87% efficiency.

The coils can be SMALL due to high frequency solution, this one run on 1.5MHz.

A good designer dont only think about the output to be clean,

the input can actually end up generating more problems in your plane,

some receivers can not handle ripple in special frequency ranges, so that is also an important design critera and must be double checked, I know 455Khz to be a pain for almost all FM RC receivers,

so never design a switcher that radiate 455khz or harmonics of that, if to be used on RC planes.

Noise is not only in wires, conducted emmision,

noise can be airborne, radiated emmision.

noise can be magnetic, and noise go both ways, called immunity.

Static discharge or lightning pulses are also funny, they generate voltage drops over even thick wires or tracks, due to their high risetime and hi current,

in bad designed electronics this is often seen to kill stuff and it is hard to prove what happened.

in some applications like LNA supply, they are often relatively low current,

so the loss of a linear is no problem, the lowest possible noise solution is more important in such cases, see here for an example:

http://www.webx.dk/rc/video-wireless/Lna2425/lna.htm

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