CrabCam Part Five: Final Thoughts

The Camera:

I was relatively happy with the camera. I think the LED's added some clarity in murky water, but I'm not sure the trade off was worth the cost. Having to deal with the stepdown coverter in the cable was a bit of a pain. I'm considering using a five volt camera if I can find an inexpensive one, and providing the 5 volts from the battery end in the buoy. The waterproof case worked well and it was cheap. The Cable: The cable was very inexpensive. The problem is the when you have to deal with individual wires IN the cable: they are very small. It's like soldering hair! Also once you take the cable apart and reassemble it you've created a weak spot in the cable and it's likely to break under the weight of the trap. You have to make sure you really reinforce the joint and make sure the rope is taking all the weight - not the cable! The Video Transmitter: I bought the cheapest unit I could find, because I figured if the buoy leaked (very possible in the experimental phase) I'd fry it. It was only about 200mw. While the camera was about 500 meters away the video would drop out from time to time. I don't know if that's a function of the strength of the transmitter, the receiver or the antennae. I tried different antennae and it didn't seem to make a difference. I've got a 650mw transmitter that I'll try next spring. The On/Off Relay: The NRF24L01 transmitter worked well, but at 500 meters I was about at the end of its effective range. I've been experimenting with LoRa units that have a lot more range - but the trade off is that these units use a lot more power - and the battery size available to me is limited by the size of the buoy. I'll probably try one of the LoRa units in concert with the higher power video transmitter and see how well it works. Battery: I wasn't thrilled with the 4800mah li-ion battery. Part of the problem I suspect is that it's a cheap Chinese model. You get what you pay for. Again I didn't want to use expensive parts in an experimental unit. I can go up to about 700mah before the battery becomes too big to fit in the buoy. The Buoy: The Buoy was actually the most difficult part of the project and took over two years of trial and error until I came up with the model I have. I'm reasonably happy with it. It's watertight (yay!), floats in an upright position in even rough water, and is not too big or heavy. I would have preferred to build it with 4 inch pipe but it wasn't relatively available and parts for the pipe don't seem to exist. A slightly bigger pipe would have allowed me to use a sealed lead acid battery which give me a LOT more transmitting time - and act as a ballast for the buoy. I'm also NOT happy with the construction of the flotation ring. It's cumbersome, prone to fall apart, difficult to build, and to parts are relatively pricey (I had them on hand). I have a better idea for it, maybe cutting the end off a pipe cap and using that as a ring to attach the spokes. I'm thinking maybe of using pieces of a kids hoola-hoop for the ring (with the noodle slid over it). If anyone has a better idea for the buoy I'd sure like to hear it. The Future: It's been an interesting project, and I couldn't have done it without help of my son, an electrical engineer, who helped me through the rough spots. I intend to put to good use next season. Now all I need are the crabs!

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