74 lines
3.9 KiB
Markdown
74 lines
3.9 KiB
Markdown
# FaSTGLETree
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Simple christmas tree from 2 PCBs with pseudo-random blinkenlights. Soldering workshop subject.
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# Features / Function
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- CR2023 coin cell for power
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- 1-pos SMD dip switch for on/off
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- button for manual shifting
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- 3 pin header with jumper for switching between timer and button for shifting
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- All ICs are low voltage (down to 2V / 2.5V) variants
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- 555 Timer set at ~.5Hz
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- SIPO 8 bit shift register for patterns
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- Pattern scrambling with 2x4 NAND gates
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- Feedback from 2 NANDs into shift register
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- 16 SMD LEDs connected to shift register and NAND outputs
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- 1 yellow THT LED always-on on top
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- Transparently 3D-printable star cap
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# Learn how to solder SMD:
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[See Slides (in German)](docs/FaSTGLET-Part4-Lötworkshop.pdf)
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# PCB Manufacturing
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I usually order from JLC with the cheapest options, make sure to choose the manual placement of the order number (marker already included in Silkscreen)
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# Build instructions
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Assembly Guides: [Board A](https://fasttube.de/bestueckung/FaSTGLETree/A.html), [Board B](https://fasttube.de/bestueckung/FaSTGLETree/B.html)
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- It's recommended to make sure each PCB is in the best state it can be in and has no short circuits before combining them. Afterwards, soldering becomes more difficult.
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- For SMD parts, always solder a single pad/pin first before continuing to others
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- Paz attention to the Pin-1-Marker! On ICs, it's usually a dot, circle or line. On the PCB, it's either an elongated line or a triangle.
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- Pin 1 markings are the elongated silkscreen line and the dot/line on the IC
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- LED directions are not marked. The LED arrow should always point to the tree trunk/inwards (Anode to tip of branch)
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- The kit usually includes 3 or 4 different colors of LEDs. It's recommended to try and spread all colors across each visible surface.
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- There's no pattern to whether the LED or Resistor is on top on the LED branches. Always check the assembly guide!
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- J9 is usually not populated, it's left for external power
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- The THT LED atop should have its leads shortened to ~7-10mm
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- The THT LED atop is oriented using the flat side of its rim. The Flat side goes to the straight line, the round side to the rounded line
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- Insert the coin cell with the + facing away from the tree's stem.
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- Keep in mind the Errata section below
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## How to tell the components in the kit apart
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Since they're not labeled, you have to go off of a few clues:
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- Generally, the number of parts is the best clue. You usually have the exact amount or one more.
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- Capacitors (C) have a brown body with no letters. They come on white strips
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- Resistors (R) have a white bottom and black top, with white digits/letters explaining their value. They come on white strips.
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- `471` means `47` with `1` 0, so 470 ohms
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- `01C` means 10Kohms with 1% tolerance, no idea why
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- LEDs (D) have clear tops and come on black strips. The diode direction is indicated by the trangle on their bottom side.
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- 0603 LEDs are very hard to solder. Don't fret if they don't work first-try
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- The big ICs are labeled with a number similar to their model number
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- The rest should be guessable from the part's footprint
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# Errata
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- [2022 version] There is a pull-up resistor missing for the button. A 10kOhm THT resistor can be soldered from the backside of the bin header to the battery holder.
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- [2022 and 2023 version] Be careful to not scratch the pcb surfaces with the legs of the top LED in order not to create a short circuit
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- [2024 version] There is a missing connection betreen R5 Pin 1 and +BATT. A bodge wire from R5 (outside) to the battery holder solder point is recommended. Otherwise, the push button functionality most likely does not work.
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# Cost
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~10€ BOM @ 30pcs
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# Licensing
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Licensed under CERN OHL, see LICENSE.txt
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