Filament display clock responds to movement.

LED Filaments for Seven-Segment Displays
Seven-segment displays can be made using Chinese-manufactured LED filaments, 38mm in size. These filaments contain multiple LEDs on both sides of the substrate, all connected in parallel. Arranging them into a 3D-printed seven-segment display shape results in large, low-cost displays available in multiple colors. The filaments come in various colors and lengths, with 38mm being the most common.
The forward voltage drop depends on the color—for a white LED at 50mA, it is approximately 2.78V, while for orange it is 2.83V. No data is available on the maximum permissible current. The substrate measures roughly 0.8 x 0.4 mm, and I counted 25 LEDs per side, giving a total of 50 LEDs per filament. Even at 300mA (1W), the filament does not get warm.
Display Assembly
On my 3D printer, it was not possible to print a design for four digits and a colon in one piece, as it would be too large. Therefore, the print was split into two parts and glued together afterward. The filaments are extremely fragile, so use tweezers to bend the metal pins—the pin with a small hole is the anode. Place the filament into the 3D-printed housing, then bend back the pin on the opposite side. Solder thin, enamel-insulated wire (0.25mm) to each pin.
The filaments can be arranged in either common anode or common cathode configuration.
There are several ICs capable of driving the segments of seven-segment displays—the TM1638, for example. However, these multiplexed drivers are not able to deliver the full power (100mA) to each segment. For this reason, a direct segment drive circuit example is included here. The intensity in this design is controlled by AMS7135 chips. Each digit has its own independent intensity control, and the current adjusts based on the number of segments lit. This ensures that the segment brightness remains consistent, whether displaying the character '1' (which uses 2 segments) or the character '8' (which uses all 7 segments).
74HC595 Driver Circuit
The seven-segment common cathode LED filament array is driven on the cathode side by AMS7135 current regulators, which are PWM-controlled. The 74HC595 shift register outputs drive PMOS transistors, and each segment's anode is powered through these transistors. Segments are illuminated when the shift register output is low. No current-limiting resistors are required, as the AMS7135 limits the output current to 350mA in all cases.
For common anode LEDs, a different driver configuration is used: the 74HC595 outputs drive NMOS transistors. The sources of these NMOS transistors are connected in parallel to the "OUT" pin of the AMC7135, while each segment cathode is connected to the corresponding drain. The common anode is connected directly to +5V. Segments light up when the shift register output is high. A 2.2kΩ resistor placed in parallel with the AMS7135 provides a small bias current.
Multiplex Driver
The TM16xx series offers a simple multiplexed driving solution, with display intensity adequate for home use. A common feature of these chips is serial interface control, and they are generally capable of driving any LED arrangement, whether common anode or common cathode. The example here shows a basic TM1618 chip driving 4 common anode digits and a colon.
Example Application: Battery-Powered Digital Clock
This clock displays the time only when someone is nearby. Normally in sleep mode, it is awakened by a touch sensor or a PIR motion sensor, shows the time for 10 seconds, then returns to sleep. An Arduino reads the PCF8563 real-time clock chip and drives the hours and minutes display. TTP223: remove the LED or its resistor, connect A jumper. The PIR sensor output is inverted, the interrupt occurs on low input on D2. The time can be set using two tactile switches. In a third position of a SP3T control switch, the clock can also be operated in continuous mode—connect your charger in this case. The (AVR) code size is 5kByte.
Powered by a flat Li-Ion battery. To keep power consumption low, I used a custom-made Arduino (see: https://www.thingiverse.com/thing:5223844). Standard boards like the Pro Mini can also be used, provided the onboard LEDs and LDO voltage regulator are removed. This ensures that, in sleep state, the power consumption remains between 10–20 µA. The switch used is in fact DP3T so it would be possible to cut off the power of the sensor not in use - PIR or touch - and save more uA-s.
The housing has an aluminium sheet back and table stand. The PIR sensor housing is attached to the clock by an M2 bolt and can be rotated in the desired direction.