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+# Electrical Specifications
+
+The MICRORACK system operates within these electrical parameters to ensure module compatibility and safe operation.
+
+## Power Supply
+
+![Voltage Layout](voltage-layout.png)
+
+MICRORACK modules are placed on the breadboard and use the following **order of voltage rails for power**:
+
+| Rail | Voltage | Purpose |
+|------|---------|---------|
+| V12+ | +12V | Positive power supply |
+| V5+ | +5V | Aux positive power supply |
+| GND | 0V | Ground reference |
+| V12- | -12V | Negative power supply |
+
+> Middle section pins of the breadboards are not used for either power distribution by MICRORACK Specification and is reserved for extending I/O signals or prototyping.
+
+- **Voltage tolerance**: ±10% on all power rails
+- **Ripple**: Up to 200 mV Vpp
+
+Each power rail requires at least 2 pins (on both sides of the module), and it must be directly connected to each other to power adjacent modules between two breadboards.
+
+### Power Consumption
+
+- **Maximum current per rail**: 100 mA (on any individual power rail)
+- **Current ripple**: ≤ 50 mA Ipp (on any individual power rail)
+
+Typical modules consume 10–30 mA depending on design complexity. It is recommended to minimize power consumption as much as possible.
+
+### Power Quality and Regulation
+
+The power rails are inherently noisy. Modules should either include on-board voltage regulation or use circuits that are tolerant to power supply fluctuations.
+
+> ⚠️ **Do not use the *V5+ rail* as a voltage reference.** Instead, derive a local regulated supply using an on-board regulator. The *V5+ rail* is intended for powering digital logic and LED indicators only.
+
+### Hot-Swap
+
+When hot-swapping a module with power enabled, the power sequencing order is not guaranteed since all connector pins have equal length.
+
+Modules must be designed to briefly withstand the following transient conditions:
+
+| Condition | Effect |
+|-----------|--------|
+| GND and V12- disconnected | Up to -7V on V5+ |
+| GND and V12+ disconnected | Up to +17V on V5+ |
+| GND disconnected | Up to 24V between V12+ and V12- |
+
+In all scenarios, current is limited by the module's own consumption.
+
+If the V5+ rail powers sensitive components, it is recommended to add overvoltage protection, such as a 5.6V Zener diode, to clamp transient voltages during hot-swap events.
+
+### Reverse Protection
+
+There are no mechanical constraints preventing a module from being inserted upside down. Because of that modules **must include reverse polarity protection** (e.g., Schottky diodes) and be designed to withstand the following voltages when inserted incorrectly:
+
+| Rail | Voltage (reversed) |
+|------|-------------------|
+| V12+ | Up to -24V |
+| V5+  | Up to -17V |
+| V12- | Up to +24V |
+
+!!! warning "Important"
+
+    A reverse-inserted module must not short-circuit the power rails under any circumstances!
+
+![Power schematic example](power-schematic.png)
+
+*Example of a module power schematic with protections and regulators for internal ±5V rails.*
+
+## Signal I/O
+
+### Maximum Ratings
+
+Absolute maximum ratings for signal inputs and outputs are as follows:
+
+- **Input voltage range**: -25V to +25V (on any signal input)
+- **Output voltage range**: Must not exceed the power supply rails (i.e., output must remain within -12V to +12V)
+
+### Signal Levels
+
+- **Bipolar signals** (audio, bipolar CV): ±5V nominal (10 Vpp)
+- **Unipolar signals** (envelopes, gates, triggers, clock, unipolar CV): 0V to +5V nominal (0V to +8V is also acceptable)
+
+### Pitch CV
+
+Pitch control voltage follows the **1V/octave** standard.
+
+### Logic Signals
+
+Triggers, gates, and clock signals use the following thresholds:
+
+- **High level**: ≥ 3.5V
+- **Low level**: ≤ 0.7V
+
+Timing requirements:
+
+- **Minimum trigger width**: 100 µs (1 ms recommended)
+- **Maximum rise/fall time**: 1 ms
+
+!!! tip "Tip"
+
+    It is recommended to use a Schmitt trigger for logic inputs.
+
+### I/O Amount
+
+It is recommended to put at least two pins for each signal input and sum them together. Similarly, it is recommended to put at least two pins for each signal output and duplicate the signal to both.
+
+## Impedance Specifications
+
+### Input Impedance
+
+- **Minimum**: > 10 kΩ
+- **Recommended**: ~100 kΩ
+
+For V/Oct pitch inputs, an input impedance of approximately 100 kΩ is mandatory to prevent signal level drop and pitch detuning.
+
+!!! warning "Warning"
+
+    Avoid excessively high input impedance (> 100 kΩ), as it increases susceptibility to noise pickup.
+
+### Output Impedance
+
+- **Maximum**: < 1 kΩ
+- **Recommended**: < 100 Ω
+
+Alternative output configurations are permitted:
+
+- **Passive summing**: Use 1 kΩ output impedance with multiple directly connected pins. This allows outputs from different modules to be summed by connecting them together.
+
+![Resistor summing](resistor-schematic.png)
+
+- **Wired-OR**: Use open-emitter or diode-coupled outputs with multiple directly connected pins. This enables wired-OR logic between module outputs.
+
+![Diode wired OR](diode-schematic.png)
+
+### Output Protection
+
+All outputs must include current limiting to protect against accidental misconnection. A module output must withstand direct connection to any power rail (from -12V to +12V) without damage.
+
+---
+
+*For mechanical specifications, see [Mechanical](mechanical.md).*

docs/specs/electrical.md

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+# Mechanical Specifications
+
+To ensure compatibility between modules and accessories, all mechanical aspects must adhere to the following specifications.
+
+## Dimensions and Outlines
+
+> [PCB Outline Template for EasyEDA](https://oshwlab.com/microrack/microrack-template-1.0)
+
+![MICRORACK Module Dimensions](module-dimensions.png)
+
+The **height of the module is 2090 mil (53 mm)**. If the module has connectors on the top, it is allowed to increase the height by 400 mil (10 mm).
+
+The **Width of modules is not fixed.** To increment the module width use formula:
+
+> (N+1) * 100 mil (2.54 mm)
+
+Where N is the number of 100 mil (2.54 mm) breadboard lines the module occupies.
+
+!!! example "Example"
+
+    Module with a width of 6 lines will have a width of `6+1 * 100 = 700 mil (17.5 mm)`
+
+To easily distinguish between top and bottom of the modules, a **symmetrical triangular cutout** is made at the bottom. Height or "depth" of cutout is 60 mil (1.52 mm).
+
+## Power Contacts
+
+Each module equipped with power contacts at the bottom layer of the board. There are two pairs of contacts on each corner of the module. They power and mount the module in a breadboard.
+
+![MICRORACK Voltage Layout](voltage-layout.png)
+
+**Male Pin Headers with a 100 mil (2.54 mm) pitch** are used for all contacts. The -12V and GND contacts are located at the bottom corners of the board, while the +12V and +5V contacts are located at the top corners.
+
+!!! tip "Tip"
+
+    For specific use cases and firmer connection of interfaces and bigger cables double row male pin headers can be used.
+
+The distance between the centers of the **inner pins** is 1655 mil (42 mm). The distance from the center of the **outer pins** to the edges of the board is 130 mil (3.3 mm).
+
+!!! tip "Tip"
+
+    It is recommended to use 0.9 mm holes for standard pin headers
+
+The offset of the outline from the center of the contact to the side is 50 mil (1.27 mm).
+
+## Module Interconnection
+
+Colored male pin headers are used for connecting modules to each other. Blue ones for inputs, red ones for outputs. Black one usually serve utility functions like chaining, power extension, stylus or ground.
+
+!!! note "I/O Placement"
+
+    It is recommended to place **inputs on the left side and outputs on the right side**, at the top of the module or on the edge of the board.
+
+## Components Height
+
+The **height of components on the bottom layer** should not exceed 100 mil (2.54 mm).
+
+## Electrical specifications
+
+*For electrical specifications, see [Electrical](electrical.md).*