555friend
About the 555friend PCB
555friend is an open source PCB design by harrisoncbrammell, published on GitHub. It is a 2-layer board measuring 97.9 × 113.9 mm, with 38 components from 18 distinct parts.
Other key parts include the TLC555XD, CD4052B, 40106, 4024 and 4555. By type, the board carries 5 ICs and 5 LEDs.
From the project
A PCB designed to introduce 555 timers and their three operating states.
A hands-on learning tool for the 555 timer IC. The 555friend is a circular PCB designed to help you explore all four operating modes of the 555 timer — astable, monostable, bistable, and externally driven — with swappable RC components, real-time mode LEDs, and labeled silkscreen diagrams showing the waveforms and formulas for each mode.
The 555friend lets you experiment with a real 555 timer (TLC555) across all of its classic configurations without rewiring anything. A single button cycles through the four modes. The board automatically reconfigures the 555's internal connections for the…
Main components on the 555friend
555friend bill of materials (BOM)
38 components, 18 distinct parts — part numbers from the project's BOM.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | TLC555XD TLC555xD | DIP-8_W7.62mm_Socket | U1 |
| 1 | CD4052B | SOIC-16_3.9x9.9mm_P1.27mm | U2 |
| 1 | 40106 | SOIC-14_3.9x8.7mm_P1.27mm | U3 |
| 1 | 4024 | SOIC-14_3.9x8.7mm_P1.27mm | U4 |
| 1 | 4555 | SOIC-16_3.9x9.9mm_P1.27mm | U6 |
| 7 | 0.1u | C_0805_2012Metric | CAP_MODE_BUTTON1, CAP_decoup_555, CAP_decoup_counter1, CAP_decoup_decoder1, CAP_decoup_mux1, CAP_decoup_strig1, CAP_filter_trig_button1 |
| 1 | 1u | C_0805_2012Metric | CAP_filter_thres_button1 |
| 3 | Conn_01x03_Pin | PinHeader_1x03_P2.54mm_Vertical | CONN_cap_select1, CONN_power_male1, CONN_resis_select1 |
| 2 | Conn_01x02_Socket | PinSocket_1x02_P2.54mm_Vertical | CONN_ext_cap1, CONN_ext_resis1 |
| 1 | Conn_01x04_Socket | PinSocket_1x04_P2.54mm_Vertical | CONN_ext_drive_female1 |
| 1 | Conn_01x04_Pin | PinHeader_1x04_P2.54mm_Vertical | CONN_ext_drive_male1 |
| 1 | Conn_01x03_Socket | PinSocket_1x03_P2.54mm_Vertical | CONN_power_female1 |
| 6 | 10k | R_0805_2012Metric | Filter_MODE_BUTTON1, Pulldown_THRES1, Pullup_COUNTER1, Pullup_RST1, Pullup_TRIG1, RESIS_filter_trig_button1 |
| 1 | SW_Push | SW_Push_1P1T_NO_E-Switch_TL3301NxxxxxG | MODE_button1 |
| 1 | 10u | C_0805_2012Metric | RC_cap1 |
| 2 | 100k | R_0805_2012Metric | RC_resis1, RESIS_filter_thres_button1 |
| 2 | 2.2k | R_0805_2012Metric | RESIS_555_out_led1, RESIS_mode_led1 |
| 5 | LED | LED_0805_2012Metric | LED_555_out1, LED_mode_0, LED_mode_1, LED_mode_2, LED_mode_3 |
555friend design files
The KiCad project lives in the harrisoncbrammell/555friend repository on GitHub; these links point at the commit this page was built from.
555friend: common questions
How big is the 555friend PCB?
The 555friend measures 97.9 × 113.9 mm, has 2 copper layers and is 1.6 mm thick.
How many components are on the 555friend?
38 components, from 18 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.
Where can I download the 555friend design files?
From the harrisoncbrammell/555friend repository on GitHub, which has the KiCad layout, the schematic and the BOM; the links under Design files point to each one.
Can I use the 555friend design in my own project?
The repository has no license, so all rights stay with harrisoncbrammell. Use it as a reference, and ask the author before reusing the design.