So, the other day I’m rummaging through my parts bins and I come across this unused mini-quad frame that I totally forgot I’d had.
It’s way too flimsy to thrash hard so one good crash and you’re done but, on the plus side it’s crazy lightweight and that got me wondering: Could turn it into a full-on autonomous mini drone using mostly parts I already had lying around? Maybe. I haven’t done a maiden flight yet but that’s coming. I’m curious to see how long it takes those little RCX motors burn out under load with that 4S battery. In the meantime I’ve ordered a set of RCX H2206 1950KV motors as replacements. These are much better suited to flying a brick like this beast and are designed to handle both 4S LiPos and 6-inch props – hopefully the old motors won’t self-destruct before the new motors show up!
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Here’s a quick overview of the project:
The receiver is a FrSky D8R-XP with RSSI and telemetry. Mounted on the underside is a FrSky FBVS-01 voltage divider to monitor the battery and a DIY RC filter to average the RSSI signal into a variable DC voltage. That voltage is then fed to the RSSI input of the APM which in turn adds the battery condition to the Mavlink output that appears in the OSD. The RSSI is also monitored by my Taranis radio with plain speech and haptic warnings when the voltage reaches preset levels. The antenna tubes were made from 5/32” polystyrene tubing using a small heat gun to make the bends.
The first GPS unit I tried was a cheap NEO-6M I picked up from a Chinese reseller on eBay and proved to have the world’s worst antenna. After failing to get a satellite lock I opened up the case and discovered the antenna was filthy and had residue from where a label had been torn off – probably a mfg. reject that somebody grabbed and decided to sell anyway. Meh. Hopefully the u-blox module is good. I ordered a Taoglas replacement antenna from Digi-Key in hopes I can salvage it. The GPS unit I replaced it with is a lovely NEO-M8N that’s able to grab 14 satellites – even indoors.
The APM case is mounted using 8mm squares of vibration-isolating Zeal tape – one at each corner of the case. The APM is powered by the 5VDC linear BECs of the 12A mini 4-in-1 ESC mounted underneath.
The 12VDC supply for the VTx, FPV camera and LEDs comes from an adjustable 3A DC-DC converter I found on eBay. I’ve used quite a few of these on various copters and they’re great. Small, stable, and they’ll handle around 1.5A continuously without overheating. Best of all they’re only about $1 so I usually buy around 10 at a time. Add a large filter capacitor on the output and they’re a good alternative to a heavy LC filter for video supplies.
The Micro MinimOSD is something I haven’t tried before and it is awesome! It’s effectively a regular MinimOSD with KV Team mods but only a fraction of the size. I programmed mine to display just the essentials: GPS info., direction home, battery voltage, RSSI, and my FCC call sign. In my case showing anything more would just be a distraction.
FPV is provided by the cheap and brilliant SONY Super HAD CCD 600TVL board camera combined with a great little 200mW 1.3GHz transmitter. The output is clean, clear video and unlike 5.8GHz you don’t lose signal when the aircraft passes behind objects.
For added stability I mounted the battery under the bottom plate. This places the CG below the props and a set of Align 450 landing skids protect the battery on landing.
u-blox 6M with compassMini u-blox M8N GPS with compass
- 4-in-1 Mini 12A ESC with BLHeli
- Micro MinimOSD
- APM 2.6 flight controller
- White case for APM 2.x
- Maxbotix XL-MaxSonar-AE4
- FrSky D8R-XP receiver with RSSI and telemetry
- FrSky FBVS-01 voltage sensor
- Adjustable mini 3A DC-DC converter
- 1.3GHz VTx
- SONY Super HAD CCD 600TVL board camera
- Reptile 260 mini-quad frame
- Align HS1294AA 450 Landing Skid Set/Black
RCX H1806 2400KVRCX H2206 1950KV brushless motors 1800mAh 4s 40c LiPo2400mAh 4S 60C LiPo
- Kyosho Z8006 Zeal Vibration Absorption Sheet
A bad ESC has caused a motor to [literally] catch fire on the bench plus the weather has made a turn for the worse and I have more important projects to tackle so for now at least, the project has been moved to the back burner.
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