Survival Cheat Sheets
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Full new section text from Survival Solutions

Electronics Cheat Sheet: Circuit & Schematic Symbols
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https://noinbox.dev/survival/solutions/electronics-schematic-symbols.html

Field principle
This reference uses simplified educational symbols. Real component standards and regional symbol styles differ; always check the device datasheet and schematic legend before connecting anything.
Quick visual reference. Read the explanations and limitations before use.
On this page
Common passive and source symbols
- Resistor — zigzag or rectangle: Limits current or divides voltage. Value is measured in ohms (Ω).
- Variable resistor / potentiometer: Arrow across resistor: adjustable resistance or voltage divider.
- Capacitor — two plates: Stores electric charge; polarized capacitors have polarity markings and must be oriented correctly.
- Inductor — coils: Stores energy in magnetic fields; often used in filters and tuned circuits.
- Battery — long/short parallel lines: Provides DC electrical energy; the longer line conventionally indicates positive.
- Ground / common: Electrical reference node. Signal ground does not automatically mean safe protective earth.
- Fuse: Sacrificial overcurrent protection; value and type matter.
Active components and controls
- Diode: Conducts primarily one way; line on symbol identifies cathode.
- LED: Light-emitting diode with arrows pointing outward; requires suitable current limiting.
- NPN / PNP transistors: Three terminals; emitter arrow direction distinguishes type (NPN points out, PNP points in).
- Switch, normally open: Closes a circuit when activated; momentary switch returns when released.
- Antenna / transformer / speaker: Input/output and coupling symbols vary; check the schematic key.
Reading a circuit safely
- Start at the power source: Find battery positive, return, ground symbols and expected polarity.
- Trace connections: A junction dot indicates connected wires; crossed lines without a dot often do not connect, depending on drawing convention.
- Check ratings: Match resistor wattage, LED current, capacitor voltage and supply polarity to the parts.
- Use extra-low voltage: Build learning circuits with isolated low-voltage battery sources only; never experiment on mains or rescue transmitter circuits.
Quick component checklist
Marking | Meaning | Safe first check
R | Resistor | Resistance and power rating
C | Capacitor | Voltage rating and polarity
L | Inductor | Inductance and current
D / LED | Diode / LED | Polarity and current limit
Q | Transistor | Part number and pinout
F | Fuse | Approved type and rating
Further reading & source material
Use these sources to validate local rules, technical standards and updates. No emergency article replaces official alerts or trained responders.
- IEEE — Symbols resources
- IEC — Electrotechnical standards
- Existing low-voltage circuit guide
Related quick references
Morse code reference
Radio field guide
Back to Survival Cheat Sheets

SOURCE LINKS
https://standards.ieee.org/
https://www.iec.ch/
https://noinbox.dev/survival/solutions/low-voltage-communication-circuits.html


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Map Symbols Cheat Sheet: Terrain, Contours & Legends
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https://noinbox.dev/survival/solutions/topographic-map-symbols.html

Field principle
Map colors and symbols are not universal: read the map-specific legend. The examples here are representative topographic-map conventions, not a substitute for the legend printed on your map.
Quick visual reference. Read the explanations and limitations before use.
On this page
Map lines and landforms
- Contour line: Connects points of equal elevation; spacing indicates slope steepness.
- Index contour: Heavier contour line often labeled with an elevation value.
- V-shaped contours: Where contours cross a stream valley, their V typically points upstream; confirm with neighboring terrain.
- Ridge and saddle: Ridges are elongated high ground; a saddle is a lower pass between peaks.
- Depression contours: Hachures on closed contours can show enclosed lower terrain.
Frequently seen features
- Blue line or area: Usually watercourses and water bodies on many topographic maps.
- Green fill: Often wooded or vegetated areas; specific meaning depends on map.
- Brown contours: Elevation lines in many topographic products.
- Black or gray lines: Buildings, trails, roads and infrastructure; line style may distinguish route quality.
- Dashed tracks: May indicate trails, footpaths or approximate features; verify the map legend.
- Grid lines: Coordinate references used to locate and describe a position.
Read the legend before travel
- Scale example: At 1:25,000, 4 cm on the map represents 1 km on the ground.
- Contour interval: A 10 m contour interval means neighboring contours differ in elevation by 10 m.
- North references: True, grid and magnetic north may differ. Read the declination diagram and map publication date.
- Hazards and access: Symbols do not guarantee a route is passable, permitted or safe today.
Further reading & source material
Use these sources to validate local rules, technical standards and updates. No emergency article replaces official alerts or trained responders.
- USGS — Topographic map symbols
- USGS — Declination reference
Related quick references
Field mapmaking
Compass bearings
Back to Survival Cheat Sheets

SOURCE LINKS
https://www.usgs.gov/educational-resources/topographic-map-symbols
https://www.usgs.gov/faqs/what-declination


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Morse Code Cheat Sheet: Alphabet, Numbers & SOS
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https://noinbox.dev/survival/solutions/international-morse-code.html

Field principle
Morse is a pattern of short and long signals, not a language. Practise with a battery LED, whistle or other permitted signal method; transmitting by radio can require authorization.
Quick visual reference. Read the explanations and limitations before use.
On this page
Timing and distress signals
- Dot: Basic signal unit (one unit).
- Dash: Three dot units.
- Inside a letter: One unit of silence between elements.
- Between letters: Three units of silence.
- Between words: Seven units of silence.
- SOS: ... --- ... (repeated as needed). In formal Morse procedure SOS is a continuous prosign without letter gaps.
- Check response: Do not assume a coded light or sound signal has been noticed; prioritize official emergency channels.
Practical field drill
- Prepare: Use a fixed light source or low-voltage battery LED and agree on the alphabet before use.
- Begin slowly: Send a familiar short word using clearly distinct signal timings.
- Receive: Listen or watch for full letter groups; write down the character only after the letter-space.
- Confirm: Repeat essential information and verify that the recipient understood it.
International Morse alphabet and numbers
Dot = · = short. Dash = − = long. The characters below are International Morse, not an audio recording.
A : ·−
B : −···
C : −·−·
D : −··
E : ·
F : ··−·
G : −−·
H : ····
I : ··
J : ·−−−
K : −·−
L : ·−··
M : −−
N : −·
O : −−−
P : ·−−·
Q : −−·−
R : ·−·
S : ···
T : −
U : ··−
V : ···−
W : ·−−
X : −··−
Y : −·−−
Z : −−··
0 : −−−−−
1 : ·−−−−
2 : ··−−−
3 : ···−−
4 : ····−
5 : ·····
6 : −····
7 : −−···
8 : −−−··
9 : −−−−·
Reference: ITU-R M.1677 international Morse code standard.
Further reading & source material
Use these sources to validate local rules, technical standards and updates. No emergency article replaces official alerts or trained responders.
- ITU-R M.1677 — International Morse code
Related quick references
Schematic symbols
Radio stations and communication
Back to Survival Cheat Sheets

SOURCE LINKS
https://www.itu.int/rec/R-REC-M.1677/en


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Radio Communications Cheat Sheet: Listening Stations & Signals
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https://noinbox.dev/survival/solutions/radio-listening-stations.html

Field principle
Listen to authorized public broadcasts and permitted radio services. Monitoring private communications and transmitting without authorization may be illegal. Frequencies and channel allocations depend on country; check the local regulator and official notices.
Quick visual reference. Read the explanations and limitations before use.
On this page
Radio bands and what to expect
- Medium wave / AM broadcast: Roughly 0.5–1.7 MHz depending on region; carries public broadcasts.
- FM broadcast: Typically 87.5–108 MHz in Europe; public broadcasting and news.
- Shortwave HF: Roughly 3–30 MHz encompasses multiple broadcast and licensed radio services; reception varies with solar conditions and time.
- VHF marine channel 16: 156.800 MHz: international maritime distress, safety and calling voice channel; not a general entertainment channel.
- VHF marine channel 70: 156.525 MHz: digital selective calling (DSC) only, not voice traffic.
- NOAA Weather Radio (United States): 162.400–162.550 MHz across seven designated frequencies; regional coverage.
- Amateur radio: Permitted frequencies vary by region, class and licence; listen or transmit only as legally authorized.
What a listening station is
- Official weather/alert broadcasts: Use public radio channels and official local alert sources. NOAA Weather Radio applies in the US, not globally.
- Marine coast radio / MRCC: Coast stations and maritime rescue coordination centres provide safety services; coverage and listening schedules vary.
- Voluntary vessel radio watch: Marine crews may keep a watch on safety channels under local rules and operational conditions.
- Shortwave broadcasts: International broadcasts can travel far; keep a printed local station/frequency and schedule list and test reception.
- Radio scanner caution: Do not attempt to intercept private, encrypted or restricted transmissions. The ability to receive a signal does not automatically make interception lawful.
Make an emergency call clearly
- Choose correct channel: Use the designated emergency channel for your service and country. On marine VHF, Ch 16 is voice distress and Ch 70 DSC alerting.
- Lead with urgency: Distress MAYDAY is for grave and imminent danger; follow applicable maritime radio procedures.
- State essentials: Who you are; exact location or bearing; nature of emergency; assistance needed; number of people; repeat as instructed.
- Conserve battery: Keep nonessential traffic short, listen for responses, and maintain the watch where safe.
- Use redundancy: Have alternative ways to summon help such as emergency phone, registered beacon, visual signals and written contact list.
Make a quick listening log
- Record: Date/time (UTC), station name, frequency, mode (AM/FM/SSB), program, signal strength and source.
- Verify: Compare with up-to-date official frequency tables, current station schedules and local band plans.
- Do not rely on one source: Coverage changes due to terrain, propagation, outages, regulations and equipment.
Further reading & source material
Use these sources to validate local rules, technical standards and updates. No emergency article replaces official alerts or trained responders.
- US Coast Guard — VHF Channel information
- US Coast Guard — DSC distress
- Ofcom — radio spectrum and the law
Related quick references
Morse reference
Schematic symbols
Back to Survival Cheat Sheets

SOURCE LINKS
https://www.navcen.uscg.gov/us-vhf-channel-information
https://navcen.uscg.gov/dsc-distress
https://www.ofcom.org.uk/spectrum/radio-equipment/radio-spectrum-and-the-law


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