Wednesday 22 October 2014

Ghetto FPV monitor (on steroids)

Hello. If you know me and my interests then you will know I like copter flying. An advancement on the standard quadcopter is to add an autopilot system, or a camera + transmitter so you can see where you fly (we call this fpv:first person view). Unfortunately, adding these components can become expensive but one thing we can do to cut the price of having such a system is to hack cheap parts and meld them into more advanced things.

Lets take the latest and greatest fpv monitor system from the beloved hobbyking website. The Quanum 7" wireless diversity monitor. It costs short of £90/$140. It consists of a basic 7" monitor, a (two of) 5.8ghz video receiver, and a battery. Can it be possible to make this ourselves and shave some bucks? Lets take a look.

We can take the classic 7" LCD car monitor screen that is doing the tried and tested rounds in FPV at the moment. - Cost = £18.73

I use one of these myself, that I bought early last year for a project. It works well for me and I'm happy with it. It comes with lots of cables and wires and you have to merge those wires with a suitable Video receiver to get a wireless video signal.

Take the classic RC305 video receiver. It costs just £12.96 now. Quite a bargain.

If we merge these two items together, we can have a wireless monitor system for just £31.69

What we need to do, is remove the circuit board from the case of the RC305 so that we can fit it neatly inside the case of the LCD monitor (It does actually fit nice & neatly).

We're going to trim and solder the 3.5mm/RCA cables so that they also join neatly inside the LCD monitor to one of it's two video inputs.

First we have to snip off the big messy wires from the back of the LCD monitor, make it nice and short and neat. Go ahead, snip off all that wire, so theres just a clean-cut nub at the back of the monitor. You will have a handful of silly waste wire in your hand.
Okay. So now we unscrew and open the back of the monitor. 2xscrews in the lower corners, 4x screws for the metal mounting plate, and 2x screws for the cable gripper.

What we have now is the insides. And what we are going to do is to merge the power wires of the monitor, with the power wires of the RC305.

We can see in my image already I haveplaced the RC305 board with a single sticky pad, connected output1 of the RC305 to video1 of the LCD monitor. The RC305 wire is Coaxial, that is, it has two wires: the outer copper shield is the ground wire, the inner core is the video feed wire.

The monitor wire is a bit different than a simple coaxial wire, but still the same principle application.
We connect the coaxial wire of the RC305 to the yellow (Video in 1), and the black (video ground). We connect the red 12v Vcc to the RC305 red power wire, and likewise, the black ground wire of the monitor to the black ground wire of the RC305. That is now done.

We now have to close up the case. To do this we have to Dremmel a few holes to accommodate the RC305 antenna & the RC305 channel select switches (top pic below). And I added a T-plug for a power connector, so I can connect it to a small 3s lipo (such as a Rhino 610mah 3s). This gives me enough power for a couple of fpv flights and isn't too heavy. You can experiment with a larger lipo if you need.
Also, I added a latching switch (bottom pic) so I can power on/off both monitor & RC305. Simple to add, just snip the red wire and add the switch between the snipped red wire. I also added a headphone jack so I could listen to the quadcopter motor sound (this lets me measure ascent/descent of the copter more accurately when out of sight). All I did for the headphone jack was to connect a female 3.5mm jack cable to the RC305 audio wire (which is the spare wire next to the video wire we cut, prepped, and connected to the monitor). 
Simples. Done! Here's the finished goods:

You can mount this to your flight transmitter how you wish (I've fashioned a holder from scrap wood previously, so no cost is required.) But in the pic below I have used a purchased mount which I like and it was only £3.11.

In total, it is less than half the price of a comparable monitor and you will have made something yourself, and learned a new crafting skill too :)

But this whole 'on steroids' thing in the title. What's that about? Well, I wanted to pimp the monitor a bit more. I added a cheap mini DVR (a measly £13.56) recorder so I could record the screen picture. It is especially good for OSD overlay recording.
Once removed from it's heavy casing, it's small and lightweight. We just connect the 3.5mm jack plugs from the RC305 to the mini DVR, and make another power link to the 3s lipo that powers the monitor.

I can't see any way that the DVR recorder will fit inside the monitor case so for now the guts and wires are a little bit visually exposed, and looks a bit messy. More a case of function over form! :)
However, I am simply going to add a made-up frame around the edge of the monitor to add depth and this should allow me to hide everything inside more neatly. So, for a DVR recording & wireless fpv monitor we have a part price of just £45.25.
From what I can gather, the cheapest dvr recording wireless monitor is the skyzone rc800 at £83.67. And we beat it with price and crafting :)

So we're pumped on steroids now perhaps?... Maybe, I have more plans.

Update: 28th October 2014
Hey, so I have thought about adding droidplanner to this setup using a touchscreen and the spare channel on the monitor; the total cost shouldn't be too great, but right now i'm not feeling like the bravado just for the sake of the bravado. Instead I have a solution that cost me zero $$$.

I decided to use a cheap phone case that I found on ebay (well.. it was my girlfriend's old one). To buy, it costs just 99p or just over a dollar.

I cut a short piece of leftover copper PCB board I had spare, and sanded it smooth so that it would fit at the correct angle for me. I drilled a hole so I could attach the piece of pcb to the neck strap hole on the 9x transmtter.

I roughed up the edge and sides of the pcb sample, and roughed up a circle in the middle of the phone holder/case as seen in the picture above. Then, I just hotglued enough glue to secure the pcb to the case and left it to set solid.

Then, it's just a 'case' (ho-ho) of attaching the holder to your neck strap mount on the transmitter. In my case I just used a motor/propeller mount holder that was close by. Above is the finished product.
It sits nicely, and is secure, and not heavy to hold. It enables me to have both fpv screen + droidplanner running at the same time. This I feel, is a lot more safe and reliable than switching the screen between the two. This way I can use the mode selection buttons to allow me to have more options in flight. So, yeah, this was a free and nice extra. Maybe I'll still do the touchscreen monitor in the future, but I figure I saved myself  from doing a $100 tutorial...For now.

Happy flying :) :) :)

Update: 14th November 2014
So I have decided that I want some fpv goggles, but I don't want to pay lots of money for a dedicated set, I just want to mash what I already have and pay just a couple of £/$. I'm ghetto, remember?

So I found this thing called a fresnel lens on ebay that cost me just £1.85 and delivered to my door in 48 hours. I figure it's what all the expensive fpv goggles use to some degree. I'm not saying this is anyway equal to those expensive goggles, but it gives a crazily immersive experience, makes the screen seem so huge that you are turning your head to glance across the image at things in view, and well, saves us about £297 of our non-existant income.
I plan on two options: the simple handheld screen enlargement mount, and head mounting google cardboard style. You can make your own. or you can buy a new, relatively cheap plastic adjustable luxury version which seems quite durable and at £15 is quite an outlay for cheap hacking.

Imagine if, at the beginning of this whole article we bought off the shelf equipment instead of mashing together? £400 vs £48.09 almost ten times cheaper, but not less than ten times the fun? I leave your thoughts up to you.

and me..
*Update: Tested fpv goggle flying with my v929 ghetto copter - it was a total vomit ride, failed to stand up on my feet, kept losing my balance, disorientation, wobbling & spinning copter, didn't have a spotter to help me, and well, now i'm having a nice cup of tea and a sit down, trying not to think about the visual experience too much *pukes*.

Next: £5/$10 Headtracking* (for PC gaming & fpv)

*when I have the parts

Update 01/02/2015
I've experimented with some DIY headtracking for games, using an mpu6050 sensor. I'm happy to say that right now, it's not ready for prime time. Workarounds don't work properly, there's no proper adjustment for exponential curves, you have to use x360ce to try to make modern games work (Crysis, Alien Isolation) and the config app crashes often. I'm not really interested in going down the rabbit hole to make this work as i'm a casual gamer these days.
As for infrared headtracking using IRleds and a webcam, i'm not at this time going down that road either.

As for using DIY headtracking to control my gimbal camera, I'm happy to suggest using the legend that is Dennis Frie's headtracker. I'm highly respecting of Dennis and his SimpleOSD work inspired me to experiment with my own OSD ideas, so I place him with legend status. 
To use the headtracker is simple, you take a nano v3.0 for just £1.99, and a GY-85 sensor for just £5.50. A total price of £7.49 for a good headtracker!!

You also need to have your Turnigy 9x flashed with er9x or opentx to allow you to plug the headtracker into the trainer port or ppm point on the 9x, but you can look up how to do that, some good guides on youtube.

Right now, i'm done with headtracking. I'm enjoying some other projects I have had ongoing which have advanced rapidly recently so i'm focussing on those and I don't really have a need for headtracking, but for discovery, further code learning and experimentation.

1 comment:

Unknown said...

i have gone through your blog.
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