This week I found myself doing a lot of wiring, connecting sensors to Raspberry Pis, and then having issues with those connections. Here’s a couple items for this week’s round-up, mostly electronic-centric

  • Voltage on Sensors
  • Hydroponics Drainage 1/2 in pipe vs 1 in pipe
  • Backwards Connector, a better IDE Connector?
  • GoPro Camera mount using a desk lamp

Voltage on Sensors
5v or 3.3v, some sensors work with both, but it can change up the circuit depending on what the input voltage is. Got burned by that this week and had the wrong voltage going to a sensor. The temp sensors, D18S20, can do either. The DHT11 Humidity likes 5v, but works with 3.3 as well. Buttons/Switches seem to go with 3.3v and a simple resistor. An LCD panel likes 5V not 3.3V, but I heard it can do it with some changes. Been using the better pin organization chart I talked about in last weeks wrap-up need to stick with that and not second guess what went where.

The DHT11, the pin numbering is not great, that’s Positive (VCC), the Data out (GPIO), and Ground (GND). At first I thought it meant “these are the output pins”, silly me.

Hydroponics Drainage 1/2 in pipe vs 1 in pipe.
Had a lot of overflows and not enough flow with my Hydroponics setup at the beginning of the week, resulting in losing a lot of the nutrient medium. I used 1/2″ pipes and connectors for the input as well as the output and it is not draining great. I feel the air gets trapped and its too narrow where surface tension and/or some other fluid dynamics principles must be coming in to play. Even when the tube is on a downward slope with no blockage and a short run, as the bed fills the output only drains at a trickle and the water level quickly rises above the connector, it probably does not drain as fast as it fills, since it’s gravity controlled where the input has a pump supplying some amount of water pressure. I ordered some 1″ tubes and connectors to replace the outputs and I’ll keep the inputs at 1/2. Hopefully that’ll solve the issue but they’ll take a bit to arrive.

Backwards Connector, a better IDE Connector?
Oh this weekend I screwed up bad. I was finally ready to hook up a bunch of sensors and wiring that took quite some time to get right. I ended up hooking up the IDE backward so that pin 1 was at the end, at pin 40 instead. I easily lost 2+ hours trying to figure it out and troubleshooting why nothing was working. It was finally when I broke out the multimeter and hooked it up to the bare pins that I realized the orientation was all wrong. I’m writing this a few days later and it still stings. The whole setup was a big rats nest to begin with so its my own fault, and I knew that it would come back to bite me. But this also got me thinking, a Pi is 40 pins but there’s no way to “polarize” it so that there’s only the correct way to put on a IDE plug. I ordered some different pins and connectors, as well as some glues to try out some different solutions for attaching wires to the pi in a way that’s not going to easily fall off and cause such a headache again. I might even try to 3d print an easier connector. I guess stay tuned for some updates on what worked and what didn’t.

Tracing wires and connectors, with a total lack of cable management.

GoPro Camera mount using a desk lamp.
After cleaning up the work areas I wanted to film and do some time lapses of the connectors I was working on. Decided to use the GoPro since it’s so small, but I wanted it in an overhead orientation to get a better shot of the workspace. Didn’t want to use a big tripod, so after failing with just sticking a mount to a lamp, I used a spare piece of aluminum and drilled the proper holes and mounted the GoPro that way. The weight of it makes it torque a bit to the side so might need a stabilizing clamp or counter weight to solve that

2 inch aluminum with some options to change positions and add something different later.

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