gohm

  georg
golang
  h
  m

A zero dependency, very small footprint, electrical engineering CLI utility for calculations and component identification

Installation

Caution

This was not intended or created in mind to be a programmatic tool. This is additionally not published to pkg.go.dev - I just wanted it to be open source for feedback, discussion and contributions

1. Download the binary of your choosing from the latest pre-compiled releases
2. Run ./<filename> -v

Optionally add it to your PATH:

1. Rename the downloaded executable to gohm
2. Add the renamed executable to a bin folder of your preference or add it to your PATH
3. Restart terminal
4. Test with gohm -v

Input Formats

gohm supports multiple input formats for convenience (support is specified on individual flags):

Shorthand Notation

Values can be specified with SI prefixes:

• 1k = 1000
• 4.7k = 4700
• 100μ = 0.0001
• 10n = 0.00000001
• 47p = 0.000000000047

RKM Code Notation

Component values using letter as decimal point:

• 4K7 = 4700 (4.7k)
• 10K = 10000
• 4R7 = 4.7
• 47R = 47
• 4n7 = 0.0000000047

Unit Suffixes

Optional unit identifier suffixes:

• 12V, 5mA, 1kHz, 100μF, 10kΩ

Commands

calculate

Perform electrical calculations

Subcommands

calculate 555

Calculate 555 timer

Flags:

Flag	Alias	Enum	Description
-capacitance required	-c		Capacitance value (F) - supports RKM & shorthand
-resistance required	-r		Resistance value (R) - when specified 2 times - circuit is assumed astable - supports RKM & shorthand
-format		abbr (default), raw, json	Output format

Examples:

> gohm calculate 555 -capacitance 10μF -resistance 100k
  → time=1.1s

astable circuit example - providing 2 resistors

> gohm calculate 555 -capacitance 1μF -resistance 1k -resistance 1k
  → time_low=693μs time_high=1.386ms frequency=480Hz

calculate capacitance

Calculate total capacitance of capacitors - values are n args passed in - args supports RKM & shorthand

Flags:

Flag	Alias	Enum	Description
-circuit		series (default), parallel	Type of circuit
-format		abbr (default), raw, json	Output format

Examples:

> gohm calculate capacitance 10μF 22μF
  → capacitance=6.875μF

> gohm calculate capacitance 10μF 22μF 18μF -circuit parallel
  → 50μF

calculate current-divider

Calculate current for parallel components - values are n args passed in

Flags:

Flag	Alias	Enum	Description
-current required	-c, i		Input current - RKM & shorthand supported
-circuit		resistive (default), capacitive	Circuit divider type - resistive & capacitive args support RKM & shorthand
-format		abbr (default), raw, json	Output format

Examples:

> gohm calculate current-divider -current 6A 10 20 22
  → r1=10Ω current=3.0697674418604644A
    r2=20Ω current=1.5348837209302322A
    r3=22Ω current=1.3953488372093021A

> gohm calculate current-divider -current 6A 10pF 22pF 18pF
  → c1=10pF current=1.2000000000000002A
    c2=22pF current=2.64A
    c3=18pF current=2.16A

calculate missing-resistance

Calculate a resistance value needed to complete a parallel circuit - resistors are n args passed in - RKM & shorthand supported

Flags:

Flag	Alias	Enum	Description
-target required	-t		Desired total/target resistance - RKM & shorthand supported
-format		abbr (default), raw, json	Output format

Examples:

> gohm calculate missing-resistance -target 150 250
  → resistance=374.99999999999994Ω

> gohm calculate missing-resistance -target 1k 2.5k 2k
  → resistance=9.999999999999996kΩ

calculate ohmslaw

Calculate Ohm's Law values (V=IR, P=IV, etc) based on 2 input values

Flags:

Flag	Alias	Enum	Description
-current	-c, -i		Current value (I) - shorthand supported
-power	-p		Power value (W) - shorthand supported
-resistance	-r		Resistance value (R) - can be specified multiple times for series - RKM & shorthand supported
-voltage	-v		Voltage value (V) - shorthand supported
-format		abbr (default), raw, json	Output format

Examples:

> gohm calculate ohmslaw -voltage 5V -current 5A
  → voltage=5V current=5A resistance=1Ω power=25W

> gohm calculate ohmslaw -voltage 5V -resistance 20
  → voltage=5V current=250mA resistance=20Ω power=1.25W

series total resistance 40Ω

> gohm calculate ohmslaw -voltage 5V -resistance 20 -resistance 10 -resistance 10
  → voltage=5V current=125mA resistance=40Ω power=625mW

calculate resistance

Calculate total resistance of resistors - values are n args passed in - args supports RKM & shorthand

Flags:

Flag	Alias	Enum	Description
-circuit		series (default), parallel	Type of circuit
-format		abbr (default), raw, json	Output format

Examples:

> gohm calculate resistance 5k 2.5k 5k
  → resistance=12.5kΩ

> gohm calculate resistance 5k 2.5k 5k -circuit parallel
  → resistance=1.25kΩ

calculate voltage-divider

Calculate output voltage for series components

Flags:

Flag	Alias	Enum	Description
-voltage required	-v		Input voltage - shorthand supported
-capacitance	-c		RKM & shorthand supported
-resistance	-r		RKM & shorthand supported
-frequency	-f		used only with a resistor <-> capacitor divider type - shorthand supported
-format		abbr (default), raw, json	Output format

Examples:

> gohm calculate voltage-divider -voltage 9v -resistance 3k -resistance 3k
  → voltage=4.5V

---

identify

Identify electrical components by visual indicators

Subcommands

identify capacitor

Identify capacitor value

Flags:

Flag	Alias	Enum	Description
-eiac	-code		The eia code or identifier - supports 2-4 digit codes including SMD & EIA-198
-format		abbr (default), raw, json	Output format

Examples:

2 digit code

> gohm identify capacitor -eiac 21
  → nominal=21pF min=nil max=nil

2 digit eia-198 code

> gohm identify capacitor -eiac A8
  → nominal=100μF min=nil max=nil

3 digit code - SMD or ceramic

> gohm identify capacitor -eiac 100
  → nominal=10pF min=nil max=nil

3 digit decimal

> gohm identify capacitor -eiac 9R4
  → nominal=9.4pF min=nil max=nil

4 digit code

> gohm identify capacitor -eiac 123B
  → nominal=12nF min=11.988zF max=11.988zF

4 digit decimal with tolerance

> gohm identify capacitor -eiac 6R7K
  → nominal=6.7pF min=6.029999999999999yF max=6.029999999999999yF

identify resistor

Identify resistor value from color bands - color bands are n args passed in

Flags:

Flag	Alias	Enum	Description
-format		abbr (default), raw, json	Output format

Examples:

> gohm identify resistor red red brown
  → nominal=220Ω min=176Ω max=264Ω temp_coefficient=nil

eia shorthand

> gohm identify resistor rd rd bn rd
  → nominal=220Ω min=215.6Ω max=224.4Ω temp_coefficient=nil