Version 2

     

     

     

    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 NameManufacturerQuantityBuy KitBuy Kit
    TLC555IP IC, TIMER, 555, PDIP8TEXAS INSTRUMENTS1Buy NowBuy Now
    SN74HC594N, Shift Register, 74HC594, Serial to Parallel, 1 Element, 8 bit, DIP, 16 PinsTEXAS INSTRUMENTS2Buy NowBuy Now
    SN74HC04N, Logic IC, Inverter, Hex, 1 Inputs, 14 Pins, DIP, 74HC04TEXAS INSTRUMENTS1Buy NowBuy Now
    V23079B1208B301, Signal Relay, 3 VDC, DPDT, 2 A, P2/V23079 Series, Through Hole, Latching Dual CoilAXICOM - TE CONNECTIVITY1Buy NowBuy Now
    2N3904, Bipolar (BJT) Single Transistor, NPN, 40 V, 200 mA, 625 mW, TO-92, Through HoleMULTICOMP PRO1Buy NowBuy Now
    C503B-RCS-CW0Z0AA1, LED, Red, Through Hole, T-1 3/4 (5mm), 20 mA, 2.1 V, 630 nmCREE12Buy NowBuy Now
    MCPAS6B2M1CE7, Industrial Pushbutton Switch, 15.2 mm, SPST, Off-(On), Round, BlueMULTICOMP PRO1Buy NowBuy Now
    MF25 2K7, Through Hole Resistor, 2.7 kohm, MF25 Series, 250 mW, ± 1%, Axial Leaded, 250 VMULTICOMP PRO12Buy NowBuy Now
    MF25 3K, Through Hole Resistor, 3 kohm, MF25 Series, 250 mW, ± 1%, Axial Leaded, 250 VMULTICOMP PRO1Buy NowBuy Now
    MCRE000037, Through Hole Resistor, 1 kohm, MCRE Series, 125 mW, ± 5%, Axial Leaded, 200 VMULTICOMP PRO1Buy NowBuy Now
    MCF 0.25W 10K, Through Hole Resistor, 10 kohm, MCF Series, 250 mW, ± 5%, Axial Leaded, 250 VMULTICOMP PRO4Buy NowBuy Now
    MRS25000C3004FCT00, Through Hole Resistor, 3 Mohm, MRS25 Series, 600 mW, ± 1%, Axial Leaded, 350 VVISHAY1Buy NowBuy Now
    MCGPR35V475M5X11, Electrolytic Capacitor, 4.7 µF, 35 V, MCGPR Series, ± 20%, Radial Leaded, 2000 hours @ 85°CMULTICOMP PRO1Buy NowBuy Now
    MCGPR35V106M5X11, Electrolytic Capacitor, 10 µF, 35 V, MCGPR Series, ± 20%, Radial Leaded, 2000 hours @ 85°CMULTICOMP PRO1Buy NowBuy Now
    K104K15X7RF53H5, Multilayer Ceramic Capacitor, 0.1 µF, 50 V, Mono-Kap Series, ± 10%, Radial Leaded, X7RVISHAY5Buy NowBuy Now
    C317C103K5R5TA, Multilayer Ceramic Capacitor, 10000 pF, 50 V, Goldmax, 300 Series, ± 10%, Radial Leaded, X7RKEMET1Buy NowBuy Now
    1N4001+, Standard Recovery Diode, 50 V, 1 A, Single, 1.1 V, 30 AMULTICOMP PRO2Buy NowBuy Now
    2227MC-08-03-18-F1, IC & Component Socket, 8 Contacts, DIP Socket, 2.54 mm, 2227MC Series, 7.62 mm, Phosphor BronzeMULTICOMP PRO1Buy NowBuy Now
    2227MC-16-03-09-F1, IC & Component Socket, 16 Contacts, DIP Socket, 2.54 mm, 2227MC Series, 7.62 mm, Beryllium CopperMULTICOMP PRO2Buy NowBuy Now
    2227MC-14-03-10-F1, IC & Component Socket, 14 Contacts, DIP Socket, 2.54 mm, 2227MC Series, 7.62 mm, Beryllium CopperMULTICOMP PRO1Buy NowBuy Now
    RTF5010, LED Housing, 9.5 mm x 12.5 mm, Black, Plastic, 5mm / T1 3/4 LEDsKINGBRIGHT12Buy NowBuy Now
    1591TSFLBK, Plastic Enclosure, Multipurpose, Plastic, 120 mm, 80 mm, 59 mm, IP54HAMMOND1Buy NowBuy Now
    2465, Battery Holder, AA x 3, Wire LeadsKEYSTONE1Buy NowBuy Now
    RE520-HP, Prototyping Board, FR2, Epoxy Paper, 1.5mm, 100mm x 160mmROTH ELEKTRONIK1Buy NowBuy Now
    221-612, Pluggable Terminal Block, 2 Ways, 20AWG to 10AWG, 6 mm², Push In Lock, 41 AWAGO4Buy NowBuy Now

     

    Additional Parts:

     

    Product Name
    AA Batteries (3)