diymore 5pcs Capacitive Soil Moisture Sensor Module TLC555 3.3-5.5V Wide Voltage Wire Corrosion Resistant Soil Humidity Detection 3-Pin Gravity Sensor Garden Watering DIY Module

I got the 2.0 version. The ones I got work. A lot of other sellers on amazon sell faulty ones. One big quality of life upgrade was adding a 1M Ohm resistor between the ground pin and the output pin. If you don't the sensor will not be reactive to changes. Before adding it, when I put the sensor in water it would take 30 seconds to level out. Afterwards, its instant. The resistor acts as a way for the capacitor to bleed off extra charge. Other than that, great product.

Followup - These are hardy and reliable Senors. Using techniques found on the web, I coated the electronics with polyurethane then used marine grade 3x shrinkage heat shrink tubing. Afterwards, checked readings and all sensor values remained within +/- 5%. However, 1 Sensor failed after being accidentally stepped on in the flowerbed. I chalk it up to low intelligence on my part and does not reduce the rating. With this years dry spell, decided to design a battery operated wireless wifi Soil Moisture System for our Flower Beds to alert us when the soil started to dry out and to conserve water. During development, I am unable say how accurate measurement is in terms of raw value to actual moisture content, however each sensor measured the same moisture level within 5% of each of the 5 sensors in the set. I will be ordering more to develop a stand-alone version for potted plants.

Sensor worked but the readings were slow to change. After looking around, I discovered a YouTube video explaining that one of the resistors was not connected to ground (apparently it’s a known problem with these sensors). Soldering a short lead between R4 and ground fixed the issue and the sensor now performs much better. Giving it 3 stars because, although it’s easy to fix, it’s a manufacturing defect that should never have happened.

NE555 requires a minimum 4.5V to operate. In addition its being supplied power from the regulator so even if you supply it more than 4.5V it still won't operate properly. I understand you can get readings from this device and they move in line with expectations but you shouldn't sell something like this if you can't make it right.

these work fine, no backwards chip, complete traces.

These little gadgets work, but trying to calibrate them for your use can be tricky. Yes they report when it's wet and dry, but estimating how damp the plant you are measuring is, is tough in my opinion. But if it's just wet/dry you need it's easy.

This is a easy to use meter but would be better with directions.

These are decent probes if they were designed correctly. I ordered the tl555c variants to run off of 3.3v. Mine did not work out of the box and read a constant voltage no matter if I tested them in open air or submerged up to the marked line. The problem is the 1meg resistor is not connected to ground. You can see the schematic at the dfrobot website. Simply bridging the noted side of r4 to the ground pin resolves this issue and they seem to work okay from there. See second photo. Works nicely with the esp32 to make a cheap ioT soil probe. Please fix the problem.

I ordered these not really expecting a lot. Once I played around with them a bit and found the value range, it was easy to write a little program that was able to convert that into percentages and calibrate the range. After that, it worked perfectly.