# Blog # Relay module DIY Reverse Engineering

A relay module is a set of components that is electrically operated and works based on a signal. That can be connected to an Arduino or a transistor and or any other application that the output is a signal or a voltage. Same as relay the relay module is used to control high voltage electronic devices. A Relay module is a mechanical switch which is electrically operated by an electromagnet. When the electromagnet is activated with a low voltage, that can be 5 v, 12 v, 32 v, … it will triggers a mechanical arm that pulls a contact to make a connection between two contacts. Relay modules are used for high voltage controls, and big loads. Relay modules has low power lose in a circuit. In other hands they are slow and they are not quick as transistors. # Millimetre online conversion form

The millimetre (international spelling as used by the International Bureau of Weights and Measures; SI unit symbol mm) or millimeter (American spelling) is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length. Therefore, there are one thousand millimetres in a metre. There are ten millimetres in a centimetre. # Millimetre to Centimetre Conversion

The millimetre (international spelling as used by the International Bureau of Weights and Measures; SI unit symbol mm) or millimeter (American spelling) is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length. Therefore, there are one thousand millimetres in a metre. There are ten millimetres in a centimetre. One millimetre is equal to 1000 micrometres or 1000000 nanometres. Since an inch is officially defined as exactly 25.4 millimetres, a millimetre is therfore equal to exactly ​5⁄127 (≈ 0.03937) of an inch. # Centimetre to Metre Conversion

A centimetre (international spelling as used by the International Bureau of Weights and Measures; symbol cm) or centimeter (American spelling) is a unit of length in the metric system, equal to one hundredth of a metre, centi being the SI prefix for a factor of 1/100. The centimetre was the base unit of length in the now deprecated centimetre–gram–second (CGS) system of units. Though for many physical quantities, SI prefixes for factors of 103—like milli- and kilo-—are often preferred by technicians, the centimetre remains a practical unit of length for many everyday measurements. A centimetre is approximately the width of the fingernail of an average adult person