SAP-Plus System Clock

TomNisbet·sap-plus·schematics/clock/clock.kicad_pcb

About the SAP-Plus System Clock PCB

SAP-Plus System Clock is an open source PCB design by TomNisbet, published on GitHub under the MIT license. It is a 2-layer board measuring 102 × 96 mm, with 32 components from 22 distinct parts.

Other key parts include the NE556, 74LS02, 74LS27 and 74LS161. By type, the board carries 9 capacitors, 8 resistors, 5 connectors, 4 ICs, 3 switches and 2 diodes.

From the project

Simple As Possible (SAP) 8-bit computer with a modular PCB design

Add range switch to select from two capacitor values for the astable clock Add 4-bit counter clock divider to fix clock reset problem and allow more astable clock frequency ranges Change astable potentiometer from 1M to 100K - allows for finer control while range switch and divider still allow wide range for frequencies RUN/STOP, RST, and LD_ACT signals now hold the divider clock in reset rather than just gating the astable clock, ensuring that the clock always starts low and the first transition is a rising edge

Main components on the SAP-Plus System Clock

NE556 74LS02 74LS27 74LS161

SAP-Plus System Clock bill of materials (BOM)

32 components, 22 distinct parts.

Qty	Part	Footprint	Refs
1	NE556	DIP-14_W7.62mm	U1
1	74LS02	DIP-14_W7.62mm	U2
1	74LS27	DIP-14_W7.62mm	U3
1	74LS161	DIP-16_W7.62mm	U4
2	Bus	PinHeader_1x40_P2.54mm_Vertical	J1, J2
1	Conn_02x04_Odd_Even	PinHeader_2x04_P2.54mm_Vertical	J3
1	CLOCK SELECT	PinHeader_1x03_P2.54mm_Vertical	J4
1	EXTERNAL CLOCK IN	PinHeader_1x02_P2.54mm_Vertical	J5
1	100K	Potentiometer_Bourns_3386P_Vertical	RV1
1	STOP	SW_EG1218	SW1
1	PULSE	SW_PUSH-12mm_Wuerth-430476085716	SW2
1	SPDT	SW_EG1218	SW3
1	STOP	LED_D3.0mm	D1
1	CLOCK	LED_D3.0mm	D2
5	0.1uF	C_Disc_D3.0mm_W1.6mm_P2.50mm	C1, C2, C3, C4, C7
2	0.01uF	C_Disc_D3.0mm_W1.6mm_P2.50mm	C5, C6
1	0.047uF	C_Disc_D4.3mm_W1.9mm_P5.00mm	C8
1	1.5uF	C_Disc_D4.3mm_W1.9mm_P5.00mm	C9
5	1K	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R1, R2, R3, R4, R7
1	R-RED	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R5

Show 2 more

Qty	Part	Footprint	Refs
1	R-BLUE	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R6
1	1M	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R8

SAP-Plus System Clock design files

The KiCad project lives in the TomNisbet/sap-plus repository on GitHub; these links point at the commit this page was built from.

Layoutschematics/clock/clock.kicad_pcb
Schematicschematics/clock/clock.kicad_sch

SAP-Plus System Clock: common questions

How big is the SAP-Plus System Clock PCB?

The SAP-Plus System Clock measures 102 × 96 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the SAP-Plus System Clock?

32 components, from 22 distinct parts. The full bill of materials is listed on this page.

Where can I download the SAP-Plus System Clock design files?

From the TomNisbet/sap-plus repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.

Can I use the SAP-Plus System Clock design in my own project?

Yes, under the terms of its MIT license, which TomNisbet chose for the repository.

More boards in sap-plus