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December 30, 2013
Kind of frustrating how many places say "just hook it up to 5V", when you can't do that with this sensor. You really don't want the breakout they're selling with this sensor either. If you look at the test conditions in their datasheet, they gave the sensor itself 5V, and had a separate lead for the heater, giving it a 60s@5V, firstname.lastname@example.orgV while-taking-readings cycle. You'll get lousy results if you "just give it 5V", and you'll get very low voltages if you use the breakout and take readings while only giving it 1.5V. The gas monitor tutorial does a much better job describing that. For my circuit, I have a 5V rail, a separate 1.5V output buck converter, and a relay switching between the two. The sensor itself always gets 5V, the heater on the sensor gets switched between the 5V and 1.5V as specified, I wait 30s into the 90s read cycle to start taking readings then take them every ten seconds from 40 to 80. If you read the datasheet, that's how this is supposed to work.
Tutorial - Transistors
about 2 years ago
At one point you use a PNP transistor as a high-side switch for a 12V motor. The diagram shows 0V = on, and 5V = off. Then the text referring to it says: "This circuit works just as well as the NPN-based switch, but there’s one huge difference: to turn the load “on” the base must be low. This can cause complications, especially if the load’s high voltage (VCC in this picture) is higher than our control input’s high voltage. For example, this circuit wouldn’t work if you were trying to use a 5V-operating Arduino to switch on a 12V motor. In that case it’d be impossible to turn the switch off because VB would always be less than VE."
This is pretty confusing. This text seems to be saying that the circuit in the diagram won't work if you use a 5V Arduino, but the diagram itself says it works with a 5V control and 5V = off. I'm pretty sure there's a small wording change that would make this clear, but the way it's written now the wording and diagram seem to contradict each other.
about 4 years ago
If you're comparing these to CC1101 implementations, do yourself a favor and look hard at the page on the datasheet for the CC1101 for 915MHz applications. Then look hard at the resistor/capacitor configuration on the board you're looking at. I made the mistake of buying some of those CC1101 modules, only to find out that none of them were actually 915MHz. The stuff you can get cheaply is all 433MHz - fine for Asia, but illegal in the US. And no, while you can tell the CC1101 to switch to 915MHz, you can't magically change the resistor arrangement on the board.
This HopeRF stuff is much better, and having bought a few elsewhere, I really wish this breakout had been around a few months ago. You can solder up the RFM69 modules directly, but not easily with standard headers. And you'll want a good magnifying glass soldering stand. So much easier with this breakout.
Oh, come on! I've been beating my head in for a few months dealing with these things and Sparkfun comes along and solves half of the problems with one breakout! The awesome thing about this breakout is that these modules use 2mm pin spacing - not the .1" spacing you're used to. But the breakout changes it to .1" for you! Wow, that's nice.
If you're using this though, do read their guides, because these radios are 3.3V. Don't fry a few figuring that out. I've had much better luck with hex buffers than bidirectional LLCs too. You only need to drop the voltage on the power, SCK, CSN, and MOSI lines. Conveniently, the Arduino has a 3.3V power output. For some reason, I found SCK just didn't work with the bidirectional LLCs I tried, but a 74HC4050 hex buffer works great.
about 4 years ago
If you guys come up with a 14T, 6mm or .25" bore, 10DP gear, I'll buy four of them right off the bat. The most common self-propelled lawn mower wheels are 8" with 10DP 53T, cheap, solid, and with a nice heft. But the best motors to drive them with any torque are the ones with 6mm shafts. Surprisingly hard to find a 6mm bore gear in 10DP, but it's pretty perfect for a bigger bot.
about 5 years ago
Oh yeah, that power cell is perfect! Sweet! Thanks! I'll keep checking back for the update on the SunnyBuddy. As soon as you guys can update it I'll snatch one.
Taking a long bike trip. I'll have a bike hub generator (6VAC, 3W max) and a small solar panel (12VDC, 3W max). I have a rectifier circuit already for the generator that supposedly will output 6VDC. Bad idea to hook the generator output up as a second input? (People do this kind of thing with combined wind/solar, but some controllers handle it well and some don't.)
Second, my loads would be all 5V - nano, charging for iPod, some tablet, NiMh batteries. I don't see any 5V LiPo batteries anywhere. The datasheet for the chip says it will charge other batteries. Sounds like it's set in the design for the LiPo batteries though. If I used this, I'd want to go with the LiPo batteries and use a step-up converter to power all of my 5v stuff, right?
Sorry, but you're both using terms that semi-noobs like me won't understand. The hook-up guide uses the term "clear solder", and razor_sparks says "solder glob". Looking up "clear solder" on Google, both as "define "clear solder"" and just "clear solder" gives lots of hits for removing solder. If it's a term of art, it doesn't look like most people know what it means. Doesn't seem to be in the tutorials either. I'm not even going to look up "solder glob".
Correct me if I'm wrong. If I want to use one panel, I can either use the barrel connector, or the "Solar In" pair of solder holes right next to the barrel connector. Or I could remove the solder ("clear solder") from J1, solder ("connect solder" or "solder glob") the two sides of J2, and use the other "Solar In" set of holes. (The schematic is a little confusing since it calls that J3, but there's no J3 labeled on the board.)
If I want to use two panels, I should remove the solder at J1, solder the two sides of J2, and use the "Solar In" set of holes farthest from the barrel connector. And razor_sparks is right, that puts your two panels in series. I think all of this is confused some because there are three footprints for inputs on the board, it comes with a barrel jack on the first one, and the other two aren't labeled separately, and the schematic only shows two footprints, the two for the barrel connectors.
No public wish lists :(