Over-engineering a two-zone thermometer

We love the extra touches that [Andrianakis Haris] added to his two-zone electronic thermometer. It includes features that you just wouldn’t find on a mass-market commercial product because of issues like added cost. For example, you can see that the PCB juts up above the LCD display, allowing the module to be mounted on a pair of screws thanks to the keyhole shape that was drilled in the substrate. I increases the board size greatly, but on a small hobby run this won’t usually affect the price of the board depending on the fab house pricing model.

The design uses an ATmega8 microcontroller to monitor sensors in two different places. There is an onboard LM35 temperature sensor for monitoring the space where the unit resides. A remote sensor module uses a DHT-11 chip to gather data about temperature and humidity. That sensor is wired, but there is one wireless option for the device. Data can be pulled down from it via an optional Bluetooth module which can be soldered to a footprint on the back of the board.

Check out the video after the break to see temperature readings pulled down wirelessly.

Comments

  1. jarfil says:

    What do you mean by over-engineered? It’s not even 8-zone, which is a snap using i2c sensors…

  2. Haku says:

    I’ve got an indoor/outdoor thermometer unit with humidity & clock which is very useful but it’s missing one feature I’d like: realtime temperature graphs.

    With graphs showing the last hour of temperature it would give you an indication of wether the temp is dropping/steady/rising.

  3. macegr says:

    That is probably 2 cents worth of extra PCB and milling on a small production run…I’ve seen many mass production PCBs that use large areas of PCB for structural purposes. It might be significant extra cost on a prototype run, like BatchPCB.

  4. SpiralBrain says:

    Been working on something similar using multiple one wire DS18B20, the keyhole shape mount is a brilliant idea for people like me who do not have access to suitable enclosures.

  5. Bhima says:

    I would love to tinker around with something like this… Unfortunately I just have radiators with knobs on them and that just does not really lend itself to easy automation.

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