Hello,
Thanks for the responses.
I do have a soldering iron and small lab at home so I could make the mod to an SD card reader than needs it.
In the photo of the card reader above I see an LVC125A tri state buffer.
The adafruit version uses a CD4050 digital buffer, not tristate, right?
https://learn.adafruit.com/adafruit-micro-sd-breakout-board-card-tutorial/download
So i’m confused, wouldn’t the tristate version be better since it wouldn’t disturb the bus that is shared with other SPI devices?
What is the part number of the one that was modified in the photo above? The yellow wire that connects the MISO pin to resistor, where is that on the schematic? I mean what is the mod doing?
Why use a TMP36? That’s ancient tech. A digital temperature sensor would be better (such as the DS18B20).
I chose the TMP36 because I have used them before. I did get some code running using the ADC to convert the TMP36 voltage to a temp reading with the serial monitor. It’s the only code I’ve actually run on an Arduino (ignoring the blink program of course)
The DS18B20 does look interesting but I would like to get an SD card reader working first. I’m looking at a DS18B20 Maxim datasheet, 1 wire protocol? How does that work with the Arduino? Have you used this without the Vdd pin? Any hiccups in parasite power mode? I don’t see the value of the Cpp bypass cap. The temp sensor would be 3-4 feet from the micro.
My project is adding an internal fan to a 60qt cooler for road trips. I put a thermocouple in my cooler, loaded it with ice and noticed inside the cooler at the highest point (just under the lid) the temp stabilized at 58F (external ambient was 80F) but with a fan it drops to 42F. Next I put the ice in a metal bucket had the fan blow on the bucket and temp dropped to 40F and no watery mess! The fan runs from the 12V cigarette lighter in my van which also charges a battery pack that will run the fan when my van is off. I took the whole thing on a road trip replacing the ice when we stopped for gas.
It worked quite well but has one flaw. The ice retention. Half the ice melts in about 3-4 hours. The water that collects at the bottom of the bucket doesn’t help either (a separate problem). The outside of the cooler (especially the lid) feels a little cool from the fan pushing the air into the cooler walls.
What I need is to cycle the fan on and off depending on temperature. Probably should slow the fan down too. But before I can do that I need an accurate temperature map on the inside of the cooler under all different conditions over several hours. A micro and a few temper sensors can help me do that.
Anyway, that’s my story.
-kooner