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Haku

Motor / speed controller inteference?

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I recently got a 1000mw 1.2ghz transmitter/receiver set and put it on my Tamiya mini monster truck, first I tried powering the camera+tx from the car's 6-cell battery pack and it worked but as soon as I started driving around the receiption broke up because of the motor and/or electronic speed controller.

So then I tried powering the camera+tx off an 8-AA pack and it works very well, but the additional weight on the already heavy car doesn't help with it's stability, so if I were to run a DC-DC converter off the 6-cell battery pack would it produce a stable enough 12v which would stop inteference from the motor and electronic speed controller?

BTW I found some cheap pre-capacitor'd DC-DC multi-voltage output converters at http://www.dimensionengineering.com/ and they post internationally without charging the earth like some electronic parts companies, which is great for me in the UK

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if I were to run a DC-DC converter off the 6-cell battery pack would it produce a stable enough 12v which would stop inteference from the motor and electronic speed controller?
It is worth a shot. You'll want a DC-DC supply design with low EMI/RFI so that the R/C Rx does not suffer glitchy operation.

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I think part of the problem with running the cam+tx off the 6-cell pack was not enough voltage for the tx, I hope a DC-DC converter will sort this out, I'll be ordering a couple next week because I've got other projects that would benefit from a DC-DC converter.

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I think part of the problem with running the cam+tx off the 6-cell pack was not enough voltage for the tx...
The usual problem is that the motor's commutation ripple dips well below the video gear Vreg's allowed voltage. So the voltage must be increased to account for that. However, the DC-DC's EMI/RFI from the switching inductors can burden the installation with R/C rx noise. Success will depend on the DC-DC you use and a little luck.

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I've just ordered 3 of the Adjustable Switching Regulator units and if they don't help reduce motor/speed controller inteference then no real loss because I have some non-wireless projects they can be used on.

Will report back when I've received them in a week or so.

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I am officially having a bad month, all I want to do is put a CCD camera on my RC car and drive it around using some LCD glasses but for every two steps forward I trip and fall on one of the steps;

Last week I discovered my 1000mw AV transmitter doesn't have reverse polarity protection... so have ordered another one.

Today I received the 3 DC-DC converters and wired one up, then discovered I'd bought the wrong darn units, the ones I'd bought only do down conversion and I have no need for them, I was going to use two for a couple of projects that would make me some money and so now I currently can't afford to order the correct DC-DC converters for a while.

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I'm feeling quite disheartened at the moment and am wondering if all this hassle is worth it for the fun of driving my RC car in FPV.

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Ouch :(

If AA's are too heavy for a separate battery, why not go for either 8AAA, or even better one 3s LiPo??

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Any chance the vendor will exchange the wrong units for something you can use?

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If the DC-DC thing doesn't work out then I was going to try an 8x AAA pack, I haven't looked at using lithium batteries for any sort of project yet because don't you need a new charger that can handle them? those video clips of lithium batteries on fire after purposely over charging look a little scary

I'll contact the vendor tomorrow when I'm not feeling so drained and see if they'll exchange the unused converters for one(s) I do need. The week+ postage time for UK <> US doesn't help matters much.

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Of course, but budget-wise you can certainly get a charger for about the same amount than the DC-DCs plus shipping ;)

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The DC-DC unit I want is $26 including postage, LiPo chargers can be had that cheap but I'd still need to get a battery or two ;)

When I can get some cash I'm going to order the correct DC-DC converter and try again, I have two things I want to try the DC-DC's on, 1000mw transmitter on the car and the other's a secret because it could potentially make me quite a bit of money (non RC based something that nobody else is doing).

edit: just ordered 2 of the correct DC-DC converters today, now for another ~10 day wait <_<

But some good news finally, I thought sod it and took the broken 1000mw transmitter apart, none of main components looked burnt out or charred except the 10v voltage regulator on the underneath.

On a hunch I took the 10v regulator off and replaced it with a jumper wire, plugged in 12v and a camera and bingo, it works! :) so I've got a spare 1000mw AV rx/tx setup on the way

Edited by Haku

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Yesterday the 2nd powerful AV transmitter arrived, I'd ordered a 1000mw one but received a 1500mw one which is nice, and it's physically smaller which is also nice.

The 2 DC-DC converters arrived this morning and I wired one into the 7.2v battery pack of my RC car, set the output to 12v and plugged in the AV tx and a cheapo CMOS camera (to be replaced with a CCD), switched the car on and spun the wheels - absolutely no inteference on the transmitted video signal at all! :) :)

One unfortunate thing was I was going to use one of the DC-DC converters to power a CCD camera off a 5v supply, and the specific 5v supply I need to power the camera from doesn't have enough amps so it won't work. Could've turned a tidy profit if it worked :\

edit: it's still two steps forward one step back at the moment, the diff casing on my Tamiya TLT-1 broke so that's out of action for 10 days whilst the replacement part gets delivered :( just as I'd gotten a real taster of driving it in FPV... will have to get one of my other cars running now

Edited by Haku

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I learned something today, you can't power the AV receiver from the RC transmitter's batteries because of the additional power drain and more importantly you get inteference lines on the output picture :(, the AV receiver and RC transmitter need to be at least a foot away from each other.

I'd non-invasively wired my RC transmitter with a couple of plugs so the LCD glasses and AV receiver power off it, great idea on paper but not practiaclly.

Also discovered that the 1.5W AV transmitter causes some nasty inteference on RC receivers that get their power from a manual speed controller that make the servos twitch like they've drunk too much coffee, and RC receivers powered from an electronic speed controller only suffers very slightl inteference from the 1.5W AV transmitter.

But I will get there, one day I will control my RC car with a FPV and no (or extremely minimal) inteference :)

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