My Mini Cp as FPV platform

[jolyboy]

Originally Posted by SkyKraken

I have questions about the Tx channels, the Tx defaults to ch8 with no connections to ground and provided are 3 channel ports, using them in combination you can obtain any of 8 channels. To select channel 1, for example, all 3 channel ports are tied to ground.

What does that mean exactly, where are these getting soldered connected to?

Is there a difference between the antenna ground and the dc power ground?
And the wire whip antenna it doesn't require a ground but the sma requires two, why?

The channel connections can be connected to ground any way you like. Most people use tiny dip switches so they can change the channel easily.

Antenna ground and DC power ground are the same.

The sma ground connections are electrially identical, ie there is two just to give a solid place for the SMA to attach to the PCB. The SMA ground allows the use of sheilded coaxial cable for extending the antenna. The other reason you use a ground with your antenna is so you can shield the antenna so you can have an exact length of the active wire that is exposed. The length of the antenna is critical.

Joly

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[Picofly]

Originally Posted by SkyKraken

I have questions about the Tx channels, the Tx defaults to ch8 with no connections to ground and provided are 3 channel ports, using them in combination you can obtain any of 8 channels. To select channel 1, for example, all 3 channel ports are tied to ground.

What does that mean exactly, where are these getting soldered connected to?

Is there a difference between the antenna ground and the dc power ground?
And the wire whip antenna it doesn't require a ground but the sma requires two, why?

Depending on my transmitter, I use jumper wires or a dip switch to select chanels. FPV Hobby's 10mW a/v transmitters come with a micro dip switch which you can solder to the pcb board. it is very handy compared to soldering.

A Whip antenna does not need electrical current thorough the antenna but circular polarized cloverleaf and skewed planar wheel antennas do. The reason why SMA connectors are grouded is that otherwise it would create a feed gap, ie. the connector would act as an antenna and substantial part of transmitting power would 'leak' before it reaches the actual antenna. For the same reason there is a grounded braid around the signal wire of a coaxial cable.

[SkyKraken]

Ah thanks, I think I understand now.

The drawing I was looking at contained a dip switch, which is now obvious, I'm a little embarrassed I asked about the Tx channels in hindsight.

I am glad I asked the antenna question, that clarified a lot of what I've been trying to understand. Not that I really understand the concept of "leak", I get confused when I read about antenna theory stuff. In the end I fall back on the belief it is just magic, powered by the same smoke I'm not suppose to let out of any electronics.

The "Planar" antennas talked about, or clover leaf like designs, are they used them on both the Tx and Rx, or just the Tx with a "Patch" antenna on the Rx?

Concerning the "Diversity" Receivers, I suppose you combine the 2 channel capability into a bridged single channel receiver, since you are just trying to pick up one Tx?

If so, then would you ever mix antenna combinations, like a clover and a patch on the "Diversity" receiver? Is the term "Diversity' just a model name or does it have an intrinsic meaning, is it more than just 2 channel Rx?

[jolyboy]

Originally Posted by SkyKraken

Ah thanks, I think I understand now.

The drawing I was looking at contained a dip switch, which is now obvious, I'm a little embarrassed I asked about the Tx channels in hindsight.

I am glad I asked the antenna question, that clarified a lot of what I've been trying to understand. Not that I really understand the concept of "leak", I get confused when I read about antenna theory stuff. In the end I fall back on the belief it is just magic, powered by the same smoke I'm not suppose to let out of any electronics.

The "Planar" antennas talked about, or clover leaf like designs, are they used them on both the Tx and Rx, or just the Tx with a "Patch" antenna on the Rx?

Concerning the "Diversity" Receivers, I suppose you combine the 2 channel capability into a bridged single channel receiver, since you are just trying to pick up one Tx?

If so, then would you ever mix antenna combinations, like a clover and a patch on the "Diversity" receiver? Is the term "Diversity' just a model name or does it have an intrinsic meaning, is it more than just 2 channel Rx?

You can mix and match antennas any way you like as long as they have the same polarity, eg RHCP with RHCP, vertical with vertical etc.

As far as I know, diversity is simply transmitting and receiving on multiple frequencies, eg, transmit on two frequencies and receive on the same two frequencies.

For example, you could transmit on 2455mhz using an RHCP antenna and on 5785Ghz on a vertically polarised antenna. Then you'd to receive on 2455mhz with any type of RHCP antenna, and on 5785mhz on any vertically polarized antenna.

Keep in mind the antennas are also specific to polarization, as well as radio frequency. Once you have that all sorted, you can also start thinking about other stuff like directional antennas...

With all that said, keep it simple

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[Picofly]

A typical diversity receiver consists of two receiver modules and a RSSI switch which monitors signal strenght from the receivers and selects to stronger one for the a/v output. In my case, for example, both a/v receivers are tuned to the same chanel (5645 GHz) but their antennas are different. There is an omni-directional antenna attached to the other reveiver and a directional antenna to the other. That means, I can fly relatively far away (~300m) to one direction and still fly around my base station (~150m).

[jolyboy]

Originally Posted by Picofly

Uh, problems again!

These FPV toys seem to be hit and miss! The first 1g video camera & 200 mW transmitter module I ordered trom FPVHobby didn't work at all. The seller never answered my enquiries so I had to buy new cam & tx to get my heli into air.

And now - after a couple of hours of use the left eye display of my Fatshark video goggles started to blink on and off until the bakclight shut down for good The unit smells like burned electronics, too.

Hey picofly, I had the same issue with my fatsharks, turns out the backlight wire was shorting out. Luckily I fixed it before it burned up.

Now my 200mw tx (fpvhobby) wjich just arrived only has like 5cm of range the rx works with my other transmitters, and I know the camera is good because I do get a picture when the antennas are almost touching.... I will investigate this more


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[SkyKraken]

I feel for you guys, I hate it when stuff is broken outta the box. You start questioning all the other stuff. I'm not sure what gets me more, having to send something in to be fixed when it cost the same to buying another, or having spent a fair amount on something new, that needs to be fixed before it has lost its "never been used" cause its new status.

Helical Axial is that the type of direct antenna you are using Picofly? And a patch antenna, is that considered directional?

Jolyboy, I hope the Tx is something easy to fix, I'm curious as to what it turns out to be.

[Picofly]

Originally Posted by jolyboy

Now my 200mw tx (fpvhobby) wjich just arrived only has like 5cm of range the rx works with my other transmitters, and I know the camera is good because I do get a picture when the antennas are almost touching.... I will investigate this more

Do transmitter's frequences match with receiver's frequences?

[jolyboy]

Originally Posted by Picofly

Do transmitter's frequences match with receiver's frequences?

yes, i checked the datasheets, plus it was part of that "super combo" they sell so you'd expect them to match. I've even tried them with different antennas and even with a fatshark rx to see if the tx was magically on a different frequency. No avail..

About to fork out another $20 for the same tx from foxtechfpv

Thanks SkyKraken, unfortunately I think its just faulty. I was hoping it was something simple too

EDIT: did any of you guys notice the FPVHobby site says use 5v, but the exact same TX on foxtechfpv site says "3.3v, DO NOT USE 5v"? I think I found the problem. I was running it from a fully charged 1s lipo unregulated

[SkyKraken]

I have a big 3' x 2' grid antenna, from back when I was running wireless B from our warehouses for computer connectivity. Its old, its looks like a bent bar-be-q grill.
If I remember correctly it was high gain, (not that I completely understand what that means) like 24db.

Could it be of use on the RX? What would I have to do make it work on 5.8ghz?

I watched a video on how to make your own clover leaf, looked simple enough, seems like the size of the "leaf" wires was the most critical. The Helical Axial looks simple enough, if you have some acrylic plastic, to support the coil.

Picofly's question in trouble shooting the TX problem, was the RX and the TX adjusted to the same channel, when do antennas fit into that scenario?

[Picofly]

Originally Posted by jolyboy

EDIT: did any of you guys notice the FPVHobby site says use 5v, but the exact same TX on foxtechfpv site says "3.3v, DO NOT USE 5v"? I think I found the problem. I was running it from a fully charged 1s lipo unregulated

There are both 3,3V and 5V versions of the 200mW transmitter module around. RangeVideo, for example sells them both.

That being said, the excact same thing happened to me when I bought a 200mW transmitter from FPV Hobby. It became burning hot when I plugged it to the battery for the first time and never recovered.

[jolyboy]

Same here, my one got ultra hot. I ordered a new one and also a spare rx just in case. Now we play the waiting game. You can expect videos here as soon as I get it up and flying

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[SkyKraken]

sorry, my posts are delayed for moderator approval, I guess, I'm new to this forum.
so my responses are lagging in the conversation..

I went with the Rangevideo 5v Tx and I plan to use a step-up regulator on a 1s lipo, I have not tried to power it yet. Are we assuming then the 3.3 - 5v Tx with the "built in regulator" are failing? And if I opted for a 5v, not 3.3 I'm good to go. I liked that 5v used .30ma less doing the same job.

[jolyboy]

You may find that you lose that 30ma advantage by the time you step up the voltage to 5v, but these small numbers we are talking about are pretty negligible when you compare them to the amount if current the main motor draws

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[SkyKraken]

Picofly, why the change to the genius canopy and are you just using servo tape to hold the camera in the nose?

[Picofly]

Originally Posted by SkyKraken

Picofly, why the change to the genius canopy and are you just using servo tape to hold the camera in the nose?

Genius V2 canopy was brighter and stronger than Mini Cp canopy (less vibrations, more crash resistant and easier to find from the field...)

I use epoxy to mount the camera. You should not use it too much, otherwise it is a pain to remove the camera from a broken canopy.

[SkyKraken]

Picofly.

Does your TX get hot?
I've just been bench testing mine, works good, but the bugger gets hot.

I checked the input voltage to the TX, its exactly 5.1 without load.

And I have another oddity, according to the instructions "without jumpers to any ground the default channel is 8", but it seems mine is transmitting on channel 1, according to how I had to set the RX dip switches to receive the a/v.

[Picofly]

Originally Posted by SkyKraken

Picofly.

Does your TX get hot?
I've just been bench testing mine, works good, but the bugger gets hot.

I checked the input voltage to the TX, its exactly 5.1 without load.

And I have another oddity, according to the instructions "without jumpers to any ground the default channel is 8", but it seems mine is transmitting on channel 1, according to how I had to set the RX dip switches to receive the a/v.

My 10 mW transmitters get quite warm but I would not say they are hot yet. 200mW transmitters get burning hot. I have found it difficult to mount a 200 mW transmitter because the tape melts.

A few people have reported that some vendors sell a/v receivers with a faulty frequency chart. I am not able to find the link now but the dip switch positions didn't match with the chanel list provided. Chanels of the transmitter are correct.

Browse for RC305 instructions and you may find the correct dip switch order.

[SkyKraken]

Thanks, I think I'll try an mount a big fan over the TX to help keep it cool.
Your info does reassure me that I'm not doing anything wrong, or something is faulty.

The new challenge, as I am staring at the heli and thinking, geeze so small, is figure how I'm gonna hang all this gear.

I've gotta redo most of it, smaller wire, maybe move to magnet wire, I had put in some connectors, keep it modular, that appears to have been a poorly conceived idea. Gotta lose wire length, connectors are out, gotta trim the fpv package. Tiny heli doesn't look good dripping in excess wire.

And I'm amazed at how vicious the fpv gear is on the battery, not only does it drink up the power, it wont stop, it will low voltage my precious lipos. I think the 10mW might have been a better choice, I don't really plan on flying far with this little thing anyways.

Heck I almost lost it in the park lawn, I'm worried to fly far with fpv, if it goes down I might not find it.. It needs a low voltage triggered beeper, so when its dying in the weeds, I hear it. My mcpx has a "beacon" on the brushless, when idle for X (programable blheli ) amount of time, it beeps the main and tail. Might be useful now. Too bad the mcpx has less places to put stuff, the servos don't have flat areas to stick stuff.

Let me know when you figure out how to get a last know gps cordinate somewhere on the gear that isn't lost in the woods. heh heh.

[Picofly]

I have tried a 200mW video tx a couple of times with no luck. It is too heavy to sub-micro helis like Mini CP and drains the flight battery quickly. Furthermore, 200mW tx modules seem to be much more sensitive to interference than FPV Hobby's 10mW transmitter. That means, one needs to build a filter (a ferrite toroid & capasitors) between the transmitter and esc or use a seprate lipo for video. Both options will add an extra 3-4g to already too heavy setup. A 10 mW tx does not need a filter. 0.7g Polulu boost regulator is enough to clean the video.

Range of the 10mW tx is limited to max. 250meters but it saves a lot of weight and provides longer flying times. What's the point having a long tange video tx if your battery limits flying times down to 2-3 min?