2 layers51 × 32 mm
LipoGardenLight
codesqueak/SmallElectronicsProjects
A collection of small projects that can be grouped together
14 parts1
2 layers51 × 38 mm
N2Graphics
codesqueak/SmallElectronicsProjects1A collection of small projects that can be grouped together
- Size
- 51 × 38 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 14
- Nets
- 26
- Pads
- 73
- Tracks, vias
- 149, 4
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 6 Dec 2023
- Updated
- 4 May 2025
Overview
N2Graphics is an open-source printed circuit board by codesqueak, from the codesqueak/SmallElectronicsProjects repository on GitHub. It is a 2-layer board of 51 × 38 mm with 14 parts on 26 nets, routed with 149 tracks and 4 vias.
It is built around the 74LS00SC, 74LS32SC and 74LS74PC, with the BC557 among its other parts. Its parts include 3 capacitors, 3 ICs, 2 switches, 1 resistor and 1 transistor.
Main components
4
74LS00SC
-0℃~+70℃ 15ns@5V,50pF 2 2.7V 2V 4 4.75V~5.25V 400uA 500mV 74LS 800mV 8mA NAND Gate - Logic Gates ROHSTexas InstrumentsLogic Gates
74LS32SC
-- Logic Gates ROHSTexas InstrumentsLogic Gates
74LS74PC
DIP-140ns 0℃~+70℃ 1 2 20MHz 3.5pF 35ns@5V,50pF 4.5ns 4.75V~5.25V 400uA 74LS Series 8mA 8mA Asynchronous Complementary D-Type Rising Edge Set and Reset DIP-14 Flip FlopsTexas InstrumentsFlip Flops
BC557
TO-921 PNP 100mA 100nA 150MHz 45V 500mW 6V 800 90mV、250mV PNP TO-92 Bipolar (BJT) ROHSDDFBipolar (BJT)
README
gardenlightCompact/kicad/README.mdSolar Garden Light
Keywords: Garden light, solar light, LED, solar, circuit, QX5252F, oshpark, jlcpcb
The Problem
I have a number of post type solar garden lamps, with small circular solar cells at the top. These suffer from a number of problems:
- The cell is too small to supply adequate power in the winter
- The plastic coating on the cell degrades and becomes opaque
- The electronics suffer from corrosion
- The illumination level is low
The Solution
I decided to see if it was possible to replace the electronics package with something that would address the issues:
- A larger, better packaged (hopefully!) solar cell was sourced
- An efficient circuit was designed around the QX5252F LED driver
- The electronics package was small enough to be dipped in a protective coating and housed in a closed container
Circuit
After looking at and testing various designs / component values I found the following configuration to be optimal.
| Component | Value | Comment |
|---|---|---|
| QX5252F | TO-94 | Datasheet |
| Solar Cell | 2.5V | Select something that will supply adequate power in winter |
| Inductor | 100µH | Alter this values to control the available current |
| Ni-MH Battery | 1.2V | Select something with adequate storage - 1900mAh Ni-MH Eneloop's seem to do the job but overspec'd |
| Diode | 1N5817 | Anything with a low voltage drop will do |
| LED | 20mA / 17500 mCd | Nice and bright with good coverage. Obtained some from Kitronik |
| Capacitor | 1μF | Electrolytic. Serves to increase brightness noticeably but uses more power. Useful for stablizing power for self colour changing LED's |
Note: The capacitor is optional and is only essential when you use colour changing LED's. If you just want to change the brightness, change the inductor.
Completed Item and Housing
The circuit can be implemented on a small piece of Vero-board. This is small enough to fit within the space taken by one AA cell. Closed dual AA cell battery holders are common and cheap to obtain from eBay, thus solving the protective environment issue.
The battery holder is then affixed onto the base of the solar cell using a silicone sealant.
Make sure to use a 'non-corrosive' type as some will attack various materials including copper.
Built Up Circuit - Front
Note: For testing, the solar cell, battery and LED are broken out on 2.54mm Dupont connector pins. For long environmental life you may want to solder the connecting wires before coating the whole unit with a conformal coating / liquid tape etc
Built Up Circuit - Back
Not the best image - the camera seems to have problems with the shiny copper surface.
PCB - JLC
I also had a number of PCB's made up by JLC. Very cheap, fast delivery and I like the selection of colours.
The gebers for both JLC and OSHPARK are included in the project if you want to make your own
Component Size Comparison
Parts
14| Qty | Value | Footprint | References |
|---|---|---|---|
| 2 | 10nF | Capacitor_THT:C_Disc_D3.4mm_W2.1mm_P2.50mm | C1, C2 |
| 1 | 220pF | Capacitor_THT:C_Disc_D3.4mm_W2.1mm_P2.50mm | C3 |
| 1 | 4K7 | Resistor_THT:R_Axial_DIN0309_L9.0mm_D3.2mm_P12.70mm_Horizontal | R1 |
| 1 | 74LS00 | Package_DIP:DIP-14_W7.62mm_Socket | U1 |
| 1 | 74LS32 | Package_DIP:DIP-14_W7.62mm_Socket | U3 |
| 1 | 74LS74 | Package_DIP:DIP-14_W7.62mm_Socket | U2 |
| 1 | BC557 | Package_TO_SOT_THT:TO-92_Inline_Wide | Q1 |
| 1 | Cap Enable | Button_Switch_THT:SW_DIP_SPSTx01_Slide_6.7x4.1mm_W7.62mm_P2.54mm_LowProfile | SW1 |
| 1 | Header | Package_DIP:DIP-14_W7.62mm_Socket | J1 |
| 1 | IC1 Pin 24 (Wait) | TestPoint:TestPoint_THTPad_D2.0mm_Drill1.0mm | TP1 |
| 1 | IC67/11 | TestPoint:TestPoint_THTPad_D2.0mm_Drill1.0mm | TP2 |
| 1 | LOGO | 80bus:sleepymouse_tiny | G1 |
| 1 | Unit Enable | Button_Switch_THT:SW_DIP_SPSTx01_Slide_6.7x4.1mm_W7.62mm_P2.54mm_LowProfile | SW2 |
Questions
How big is the N2Graphics PCB?
It measures 51 × 38 mm and has 2 copper layers, 1.6 mm thick.
What parts does the N2Graphics use?
14 parts, built around the 74LS00SC, 74LS32SC, 74LS74PC and BC557. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the N2Graphics KiCad files?
From the codesqueak/SmallElectronicsProjects repository on GitHub, at the commit this page was made from: the board is N2ScreenFlashEliminator/kicad/N2Graphics.kicad_pcb and its schematic N1Clock/kicad/N1Clock.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the N2Graphics design in my own project?
Its repository states no licence, so its author keeps all rights: ask codesqueak before reusing the design.
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