Do you make sure you brush for 2 minutes each time you brush your teeth? Today I’m making a timer to ensure I do! However rather than just coding it on a dev board, why not do it entirely microcontroller free and design it as a circuit using 555s and 74 series logic?
Bill of Material:
| Product Name | Manufacturer | Quantity | Buy KitBuy Kit |
|---|---|---|---|
| IC, TIMER, 555, PDIP8 | TEXAS INSTRUMENTS | 1 | Buy Now |
| Shift Register, 74HC594, Serial to Parallel, 1 Element, 8 bit, DIP, 16 Pins | TEXAS INSTRUMENTS | 2 | Buy Now |
| Logic IC, Inverter, Hex, 1 Inputs, 14 Pins, DIP, 74HC04 | TEXAS INSTRUMENTS | 1 | Buy Now |
| Signal Relay, 3 VDC, DPDT, 2 A, P2/V23079 Series, Through Hole, Latching Dual Coil | AXICOM - TE CONNECTIVITY | 1 | Buy Now |
| 2N3904, Bipolar (BJT) Single Transistor, NPN, 40 V, 200 mA, 625 mW, TO-92, Through Hole | MULTICOMP PRO | 1 | Buy Now |
| LED, Red, Through Hole, T-1 3/4 (5mm), 20 mA, 2.1 V, 630 nm | CREE | 12 | Buy Now |
| Industrial Pushbutton Switch, 15.2 mm, SPST, Off-(On), Round, Blue | MULTICOMP PRO | 1 | Buy Now |
| MF25 2K7, Through Hole Resistor, 2.7 kohm, MF25 Series, 250 mW, ± 1%, Axial Leaded, 250 V | MULTICOMP PRO | 12 | Buy Now |
| MF25 3K, Through Hole Resistor, 3 kohm, MF25 Series, 250 mW, ± 1%, Axial Leaded, 250 V | MULTICOMP PRO | 1 | Buy Now |
| Through Hole Resistor, 1 kohm, MCRE Series, 125 mW, ± 5%, Axial Leaded, 200 V | MULTICOMP PRO | 1 | Buy Now |
| MCF 0.25W 10K, Through Hole Resistor, 10 kohm, MCF Series, 250 mW, ± 5%, Axial Leaded, 250 V | MULTICOMP PRO | 4 | Buy Now |
| Through Hole Resistor, 3 Mohm, MRS25 Series, 600 mW, ± 1%, Axial Leaded, 350 V | VISHAY | 1 | Buy Now |
| Electrolytic Capacitor, 4.7 µF, 35 V, MCGPR Series, ± 20%, Radial Leaded, 2000 hours @ 85°C | MULTICOMP PRO | 1 | Buy Now |
| Electrolytic Capacitor, 10 µF, 35 V, MCGPR Series, ± 20%, Radial Leaded, 2000 hours @ 85°C | MULTICOMP PRO | 1 | Buy Now |
| Multilayer Ceramic Capacitor, 0.1 µF, 50 V, Mono-Kap Series, ± 10%, Radial Leaded, X7R | VISHAY | 5 | Buy Now |
| Multilayer Ceramic Capacitor, 10000 pF, 50 V, Goldmax, 300 Series, ± 10%, Radial Leaded, X7R | KEMET | 1 | Buy Now |
| 1N4001+, Standard Recovery Diode, 50 V, 1 A, Single, 1.1 V, 30 A | MULTICOMP PRO | 2 | Buy Now |
| IC & Component Socket, 8 Contacts, DIP Socket, 2.54 mm, 2227MC Series, 7.62 mm, Phosphor Bronze | MULTICOMP PRO | 1 | Buy Now |
| IC & Component Socket, 16 Contacts, DIP Socket, 2.54 mm, 2227MC Series, 7.62 mm, Beryllium Copper | MULTICOMP PRO | 2 | Buy Now |
| IC & Component Socket, 14 Contacts, DIP Socket, 2.54 mm, 2227MC Series, 7.62 mm, Beryllium Copper | MULTICOMP PRO | 1 | Buy Now |
| LED Housing, 9.5 mm x 12.5 mm, Black, Plastic, 5mm / T1 3/4 LEDs | KINGBRIGHT | 12 | Buy Now |
| Plastic Enclosure, Multipurpose, Plastic, 120 mm, 80 mm, 59 mm, IP54 | HAMMOND | 1 | Buy Now |
| 2465, Battery Holder, AA x 3, Wire Leads | KEYSTONE | 1 | Buy Now |
| Prototyping Board, FR2, Epoxy Paper, 1.5mm, 100mm x 160mm | ROTH ELEKTRONIK | 1 | Buy Now |
| 221-612, Pluggable Terminal Block, 2 Ways, 20AWG to 10AWG, 6 mm², Push In Lock, 41 A | WAGO | 4 | Buy Now |
Additional Parts:
| Product Name |
|---|
| AA Batteries (3) |
DIY Toothbrush Timer
Top Comments
Great job with the 555-based design! While watching, I forgot you built the entire circuit without a microcontroller. So when you mentioned not having feedback after pressing the start button, I first…
The Wago connectors are brill, I was somewhere a year or 2 ago and spotted someone using them and decided I need to get some. I go through lots when doing activities with school children as they make it…
Yeah! Everything with a 555 timer is cool! Nice job, Katie.
I wonder if I have any shift registers laying about...