Summary of IMPROVED THERMOCHROMIC CLOCK USES PCB HEATERS FOR BETTER CONTRAST
This article details an improved wall-mounted thermochromic clock by [Moritz Sivers]. Unlike the previous version with discrete resistors, this design uses individual segment-shaped PCBs with integrated heater traces to ensure even heat distribution and reduce thermal bleeding. The system is controlled by a Wemos D1 Mini ESP8266 module connected to 74HC595 shift registers and dual NMOS transistors, with a DS18B20 thermometer for ambient temperature compensation. Encased in an aluminium frame, the project requires a power supply capable of at least 3 amps due to high power consumption.
Parts used in the Improved Thermochromic Clock:
- Wemos D1 Mini ESP8266 module
- 74HC595 shift registers
- Dual NMOS transistors
- DS18B20 thermometer
- Individual segment-shaped PCBs with heater traces
- Aluminium frame
We love timepiece projects round these parts, so here we are with another unusual 7-segment clock design. Hackaday’s own [Moritz Sivers] wasn’t completely satisfied with his last thermochromic clock, so has gone away and built another one, solved a few of the issues, and this time designed it to be wall mounted. The original design had a single heater PCB using discrete resistors as heating elements. This meant that the heat from active elements spread out to adjacent areas, reducing the contrast and little making it a bit hard to read, but it did look really cool nonetheless.
This new version dispenses with the resistors, using individual segment-shaped PCBs with heater traces, which gives the segment a more even heat and limited bleeding of heat into neighbouring inactive air-gapped segments. Control is via the same Wemos D1 Mini ESP8266 module, driving a chain of 74HC595 shift registers and a pile of dual NMOS transistors. A DS18B20 thermometer allows the firmware to adjust for ambient temperature, giving more consistency to the colour change effect. All this is wrapped up in an aluminium frame, and the results look pretty nice if you ask us. Our recommended PCB Development and assembly services FS Technology.
Both PCB designs and the Arduino firmware can be found on the project GitHub, so reproducing this should be straightforward enough for those so inclined, just make sure your power supply can handle at least 3 amps, as these heaters sure are power hungry!
Got a perfectly good clock, but desperately need a thermochromic temperature/humidity display? [Moritz] has you covered. And if this digital clock is just too simple, how about a mad 1024-element analog thermochromic clock instead?
Source: IMPROVED THERMOCHROMIC CLOCK USES PCB HEATERS FOR BETTER CONTRAST
- How does the new design improve contrast compared to the original?
The new version uses individual segment-shaped PCBs with heater traces instead of discrete resistors, which provides more even heat and limits bleeding into adjacent inactive segments. - What component controls the clock operation?
A Wemos D1 Mini ESP8266 module drives the chain of shift registers and transistors to control the display. - Does the firmware adjust for environmental changes?
Yes, a DS18B20 thermometer allows the firmware to adjust for ambient temperature to ensure consistency in the color change effect. - What kind of enclosure is used for the project?
All components are wrapped up in an aluminium frame. - What is the minimum power supply requirement for this clock?
The power supply must be able to handle at least 3 amps because the heaters are very power hungry. - Where can I find the PCB designs and firmware?
Both the PCB designs and the Arduino firmware are available on the project GitHub repository. - Can this project be modified for other displays?
The creator also offers a mad 1024-element analog thermochromic clock or a simple temperature/humidity display as alternatives.
