Windowsill propagator thermostat

Disclaimer: This project works on AC V which is quite dangerous and anything wrong may kill you. I cannot be held responsible for any damages, injuries or loss of life. Make this at your own risk! And some connection wires, heat shrink tubing, glue, double sided adhesive tape, black spray paint, PCB board standoff spacers, M3 bolts and 1.

The actual temperature of both the soil and the air in the propagator will be measured by 2 temperature sensors. These sensors have a so-called 1-Wire interface, which means that they can be connected in parallel to one input port. To be able to increase or decrease the desired target soil temperature, 2 pushbuttons are added, as well as a 16x2 character LCD screen to provide some feedback on the current and target temperatures.

This LCD screen has a built-in backlight. To prevent the backlight from being on all the time, I decided to add some code to dim the screen after some time. To be able to activate the backlight again, I added another pushbutton. Finally, a relay module is added to switch the power to the heat cable in the propagator on and off.

Because we need some data from the Blynk app in our code later on, let's first take care of the Blynk business. Follow the first 3 step of the Blynk getting started instructions. Now create a new project in the Blynk app. As project name I chose 'Propagator'. I like the dark theme, so I chose 'Dark'. After pressing OK, a popup will be shown stating that an Auth Token was sent to your email address.

Check your mail and write down this token, we need in the NodeMCU code later on. The pictures above show how to layout the screen with these elements. By tapping each element, the detailed settings can be adjusted also shown in the pictures above. Once done, activate your project by selecting the 'play' button. The app will of course fail to connect, because there is nothing yet to connect to. So let's move on to the next step. I use the Arduino IDE application for this, which can be downloaded here.

The base of the propagator will be filled with a layer of sharp sand or very fine grit of about 2cm thick. This will spread the bottom heat more evenly.

To properly measure the 'soil' temperature, I decided to go for the waterproof DS18B20 temperature sensor. Although my propagator came with an onboard analog thermometer to measure the temperature of the air inside, I decided to add another temperature sensor to measure the air temperature electronically as well. To hold both sensors nicely in place, I created a simple wooden structure.

I took a piece of waterproof plywood and drilled a 6. This hole holds the air temperature sensor. The air temperature sensor is covered by a plastic white tube that fits inside the 12mm hole. The length of the tube is about 16cm. The tube has several 1. Idea is that the air in the black part of the tube heats up a bit, rises to the top and escapes, thus creating a flow of air around the sensor.

Hopefully this leads to a better reading of the air temperature. Finally, to avoid the sand or grit from entering, the holes for the sensor cables are filled with glue. To connect the sensors, I used an old stereo audio cable that has a stereo 3. I cut off the connectors at the other side and soldered the 3 wires my audio cable has a copper ground, red and white wire :. I isolated the soldered parts individually with some heat shrink tubing.

Also used some heat shrink tubing to keep the 2 sensor wires together. As with all propagators, position it on a flat surface out of direct sunlight. If you place it in hot sun, your plants will suffer from too much heat. The green and red lights on the front of the base indicate if the unit is on. The base can be wiped clean. The BioGreen Warming Pad may be about as simple as it can get, but what a fantastic idea for those short of storage space.

If you are taking a few cuttings or sowing just a few seeds every year, then this pad might be just what you are looking for it can be rolled up to store.

The rubber mat is splash proof, so can be wiped clean, and pots that have drained after watering can be placed back on it. As a rule, remove pots and trays to water them, then place back into the propagator once drained.

Available in three sizes — The Vitopod Propagator is far from a windowsill model. Available in two sizes, and with the option of buying a two-layer lid, it is ideal for the semi-professional or very serious gardener. The clear lid lets in the maximum amount of light and has generous vents, which are the keys to its success.

The thermostat is really easy to use and very clear — top marks for this. The standard model measures 50 x 50 x 24cm and is designed for two standard seed trays, and the large is 50 x x 24cm and can accommodate five seed trays. For polytunnel or greenhouse gardeners, and for those who want to use taller pots for cuttings — this is for you. It is ideal for those with a greenhouse bench to heat — it is probably the most cost-effective way of creating a temporary heated bench in a greenhouse.

The 40 x 75cm mat was tested the smallest model , but there are many different sizes available. The mat offers even heat distribution across a bench, and works best when placed on insulating material, such as polystyrene. The aluminium mat is spray waterproof, and can be rolled to store. My biggest criticism about this mat is that the instructions are so complicated.

These neat shrubs bring fresh and vibrant year-round interest, pleasing gardeners with colourful evergreen foliage and attractive, long-lasting blooms. Home Product guides Growing Eight heated propagators for nurturing your plants. This review contains affiliate links and we may receive a commission for purchases made. Please read our affiliates FAQ page to find out more. Garland Fab 4 Electric Heated Propagator. Garland Super7 Electric Heated Propagator. Geopod Heated Propagator — Large W.

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