## Goal

Build a handheld device that can be used to test the 8 strand ribbon cables that connect the MRFC522 readers to the RPi breakout board.

## To Do

- [x] Design & print ribbon cable tester case bottom half 🔼 ➕ 2024-05-15 ✅ 2024-06-07
- [x] Design & print ribbon cable tester case top half 🔼 ➕ 2024-05-15 ✅ 2024-06-08
- [x] Design & print ribbon cable tester battery door 🔼 ➕ 2024-06-08 ✅ 2024-06-08
- [x] Assembly the unit ➕ 2024-06-10 ✅ 2024-06-10
## Parts List

| **Part Code** | **Type**           | **Value**   | **Mfg Code**                       |
| ------------- | ------------------ | ----------- | ---------------------------------- |
| R1            | Resistor           | 68 to 75 KΩ |                                    |
| R2            | Resistor           | 1 KΩ        |                                    |
| R3            | Resistor           | 1 KΩ        |                                    |
| R4            | Resistor           | 1 KΩ        |                                    |
| R5            | Resistor           | 10 KΩ       |                                    |
| R6            | Resistor           | 100 Ω       | The ratio of R6:R7 is 1:3.3 (0.30) |
| R7            | Resistor           | 330 Ω       |                                    |
| C1            | Ceramic Capacitor  | 0.01 µF     | 104                                |
| C2            | Ceramic Capacitor  | 10 µF       | 106                                |
| RV1           | Potentiometer      | 100 KΩ      | 104                                |
| U1            | Integrated Circuit | LM555       |                                    |
| U2            | Integrated Circuit | CD4017      |                                    |
| D1 - D8       | 5mm LED            | Red         |                                    |
| D9 - D16      | 5mm LED            | Green       |                                    |
| D17           | 5mm LED            | White       |                                    |
| J1 - J2       | IDC Socket         | 8 pin       |                                    |
|               |                    |             |                                    |

## Build Notes 

- Overall current draw is 0.03 A so power is ~0.27W
## References

- [This is a good tutorial](https://www.nutsvolts.com/magazine/article/led-chaser-sequencer-circuits), but there is no capacitor to pin 5 of the LM555 as in all the other articles, which seems wrong.
- [LM555 datasheet](https://www.ti.com/lit/ds/symlink/lm555.pdf?ts=1715218052822&ref_url=https%253A%252F%252Fwww.google.com%252F)
- [4017B datasheet](https://www.ti.com/lit/ds/symlink/cd4017b.pdf?ts=1715285377632&ref_url=https%253A%252F%252Fwww.google.com%252F)
- The best [LM555 tutorial](https://www.nutsvolts.com/magazine/article/using-the-555-timer-ic-in-special-or-unusual-circuits).  It actually works.