This project is designed to introduce you to KiCad and electronics design. The gadget is battery powered and will blink a high luminosity LED as well as output a tone to a speaker. The frequency can be switched between 1 Hz and 440Hz with a solder jumper. The two integrated circuits are classics and are considered jellybean parts.
- Power supplied by 3 x AA batteries
- Generate the pulsed signal with a 555 timer chip
- Boost the battery voltage with the MC34063 DC-DC regulator
- Let the 555 timer drive 0.25 Watt into an 8Ω speaker without an additional amplifier
- Use only through hole parts in the design with two small exceptions
- Familiarize the designer with SMD parts of imperial size 0603 and 0805.
- Introduce some of the tools and techniques that are useful in KiCad
- Cut a slot in the PCB to use as strain relief for the speaker cable
- Use a two layer pcb design
- Input voltage 3.75V ±20%
- An assumption is made that an alkaline cell with 50% of the energy left is at approximately 1.25V. We are using three of these in series.
- Output current 150mA
- This is a compromise. Not all the way to 0.25 watt on the speaker and not maxing out the available current from the 555 timer chip. May change after prototyping.
- Output Voltage 6.25V
- The voltage needs to be this high to get 2.4V voltage swing on the output when pulling 150mA from the output of the 555.
- Switching frequency 100kHz
- A high switching frequency lets the inductor be small. This is the maximum frequency supported by the selected regulator.
- Output ripple voltage 100mV
- An arbitrary value. Same as Dave chose in the YouTube video EEVblog #110 - Let's Design a DC to DC Switch mode Converter.
- Getting started with a new project i KiCad
- Placing parts and connecting them on the schematic
- Place
- Rotate
- Mirror
- Move
- Grab
- Wire
- Implementing the typical application found in the MC34063 and 555 datasheets
- Choosing component values from E series of preferred numbers
- Searching for parts on DigiKey, JLCPCB and LCSC
- Choosing footprints
- Adding symbol data by using fields and the Symbol Fields Table
- Using the Do not populate and Exclude from Bill Of Materials (BOM) option
- The purpose of the 0.1µF decoupling capacitor
- Dividing a schematic into functional blocks
- Annotating the schematic
- Running Electrical Rules Check
- Switching from schematic to pcb
- Update PCB from schematic
- Move components into functional blocks
- Untangle the ratsnest
- Draw board outline
- Pre-define sizes for tracks and vias.
- 0.3mm (0.012") track
- 0.7mm (0.028") track
- 1.0mm / 0.4mm via
- Route Tracks
- Track size
- Use of vias and multiple layers
- Create filled zones for ground (and power if the board had more layers)
- Use the 3D-viewer
- Use the Design Rules Check
| Reference | Value | Manufacturer | Part# | DigiKey# | Qty |
|---|---|---|---|---|---|
| BT1 | Battery | Keystone Electronics | 2464 | 36-2464-ND | 1 |
| C1,C2 | 100u | Chinsan (Elite) | ED1E101MP26311U | 4191-ED1E101MP26311UCT-ND | 2 |
| C3 | 22u | Murata Electronics | GRM188C61E226ME01J | 490-GRM188C61E226ME01JCT-ND | 1 |
| C4,C7 | 470u | Chinsan (Elite) | EK1C471MP30812 | 4191-EK1C471MP30812CT-ND | 2 |
| C5 | 1u | TDK Corporation | FG24X7R1H105KRT06 | 445-173374-1-ND | 1 |
| C6 | 0.1u | KEMET | C320C104M5R5TA | 399-9776-ND | 1 |
| Ct1 | 240p | KEMET | C318C241K3G5TA | C318C241K3G5TA-ND | 1 |
| D1 | 1N5819 | STMicroelectronics | 1N5819 | 497-6610-1-ND | 1 |
| D2 | Green | Inolux | INL-5AG30 | 1830-1011-ND | 1 |
| L1 | 15u | Bourns Inc. | RLB0913-150K | RLB0913-150K-ND | 1 |
| R1,R4 | 180 | Stackpole Electronics Inc | CF14JT180R | CF14JT180RCT-ND | 2 |
| R2 | 64k9 | YAGEO | MFR-25FRF52-64K9 | 13-MFR-25FRF52-64K9CT-ND | 1 |
| R3 | 16k2 | YAGEO | MFR-25FTE52-16K2 | 13-MFR-25FTE52-16K2CT-ND | 1 |
| R5 | 1k5 | YAGEO | MFR-25FTF52-1K5 | 13-MFR-25FTF52-1K5CT-ND | 1 |
| R6 | 75 | Stackpole Electronics Inc | CF14JT75R0 | CF14JT75R0CT-ND | 1 |
| R7 | 8.06 | KOA Speer Electronics, Inc. | RK73H2ATTD8R06F | 2019-RK73H2ATTD8R06FCT-ND | 1 |
| Rsc1 | 240m | YAGEO | MFR-25JR-52-0R24 | 13-MFR-25JR-52-0R24CT-ND | 1 |
| U1 | MC34063AP | onsemi | MC34063AP1G | MC34063AP1GOS-ND | 1 |
| U2 | NE555P | Texas Instruments | NE555P | 296-NE555P-ND | 1 |
| Reference | Footprint |
|---|---|
| BT1 | Battery:BatteryHolder_TruPower_BH-331P_3xAA |
| C1,C2 | Capacitor_THT:CP_Radial_D6.3mm_P2.50mm |
| C3 | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder |
| C4,C7 | Capacitor_THT:CP_Radial_D8.0mm_P3.50mm |
| C5 | Capacitor_THT:C_Disc_D5.1mm_W3.2mm_P5.00mm |
| C6 | Capacitor_THT:C_Disc_D5.0mm_W2.5mm_P2.50mm |
| Ct1 | Capacitor_THT:C_Rect_L7.0mm_W3.5mm_P5.00mm |
| D1 | Diode_THT:D_DO-41_SOD81_P10.16mm_Horizontal |
| D2 | LED_THT:LED_D5.0mm |
| L1 | Inductor_THT:L_Radial_D8.7mm_P5.00mm_Fastron_07HCP |
| R1,R2,R3,R4,R5,R6,Rsc1 | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal |
| R7 | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder |
| U1,U2 | Package_DIP:DIP-8_W7.62mm |