see also:

• multimeters
• spectrum analyzers
• frequency response analyzers
• signal generators
• software defined radio (SDR) receivers
• vector network analyzers (VNAs)
• basic electronics
• logic analyzers

• oscilloscopes essentially allow visual display of changes to voltage inputs over time
• in contrast, logic analyzers, unlike oscilloscopes that display analog waveforms in real time, capture digital logic state data and display it for detailed post-capture analysis, which is especially useful for complex multi-signal digital systems
• inputs usually have BNC connections with outside ring being mains earth grounded if AC unit with a very low impedance path
  • hence if you connect the ground to the wrong thing it can damage the oscilloscope as it can carry a large current eg. connect the ground of one channel input to a different voltage to the ground of another input channel (as these grounds are connected internally). In contrast, connecting it anywhere on an isolated non-mains grounded circuit (ie. battery only device, or a AC powered device via a two-pin AC plug and DC transformer) which can't create a circuit current through the mains ground back to the scope will not be an issue. ¹⁾
• many allow more than one channel of input which allows comparing different aspects of a system at the same time points
• by using transducers connected to the inputs, one can measure other parameters such as electrical current or pressure
  • transducers convert other parameters into a voltage output which the oscilloscope can display
    • eg. a clamp meter transducer can convert current in a cable to a voltage
    • eg. a pressure transducer with its connector inserted in place of spark plugs can convert pressure in a car motor cylinder into a voltage
      • if you want to understand how your car's battery normally jump starts your car, by using an oscilloscope, see https://www.youtube.com/watch?v=LEzkoF-gAn4
• some also have built-in signal generators which can produce sine waves, square waves, saw waves, etc

• analog vs digital
  • most are now digital although older analog scopes often has better X-Y mode
  • analog uses a bulkier CRT (like in old TVs), offer faster response times but cannot store waveform data and have limited signal processing or analysis features.
  • digital scopes sample the input analog signals using an analog-to-digital converter (ADC) and convert them into digital data for display on a digital LCD screen and can store waveform data in memory, allowing for complex analysis, processing, and the ability to freeze, record or replay waveforms, have advanced triggering options, automated measurements, waveform math, and frequency domain analysis (e.g. FFT). They provide a more stable display image and higher measurement accuracy and are suitable for capturing transient events, measuring complex signals, and integration into automated test systems
• channels
  • the more channels, the more simultaneous inputs can be compared eg. pressure transducer vs battery voltage vs current
  • 4 channels is best but 2ch will cover most use cases
• bandwidth
  • the input frequency at which the input gets damped by -3dB (ie its amplitude value drops to 70.7% of its original value)
  • oscilloscopes act like a analog low pass filter which can damp the amplitude and distort the rise time, etc which we would like to avoid
  • a 200MHz rated scope can handle 40MHz with ease (1/5th the value) which is adequate for most applications
  • see https://www.youtube.com/watch?v=oZ1Dv2dVGkU for video on scope inadequate bandwidth issues
  • if using it for VHF radio, the bandwidth needs to be 1.5-3 x the radio frequency to be analyzed, thus a 100Mhz scope will only be of use for low end of VHF but may provide some qualitative analysis - a 200MHz scope will be much more useful for VHF while you would need at least 500MHz for UHF
  • limited oscilloscope bandwidth biases FFT amplitude and peaks primarily by attenuating higher frequency components, which skews the spectral representation and reduces peak amplitudes.
    • Amplitude Reduction: FFT peaks corresponding to frequencies near or beyond the oscilloscope's bandwidth will appear smaller than their true magnitude due to roll-off in the scope's frequency response.
    • Peak Distortion: Limited bandwidth causes rounding and broadening of spectral peaks, reducing frequency resolution and peak sharpness
    • Signal Shape Alteration: High-frequency harmonics and fast transients are attenuated, altering the time-domain waveform shape and leading to incomplete or biased FFT representations.
    • Gibbs Phenomenon: band-limited signals can exhibit ringing artifacts near sharp transitions, affecting the FFT spectrum's accuracy and the appearance of spectral sidelobes
    • aliasing risk: if the bandwidth limits sampling frequency or effective Nyquist frequency, aliasing might occur, causing misleading low-frequency artifacts in the FFT spectrum
  • the probe may limit the bandwidth:
    • a passive probe with switchable 1:1 and 10:1 (10V in 1V out) may only have 6MHz bandwidth at 1:1 but 200MHz at 10:1
• sampling rate
  • a measure of how many digital measurements the scope can do per second
  • 1-2GSa/sec is ideal for most use cases unless analyzing very high frequency signals - ideally sampling rate should be > 5x the frequency being analyzed
• memory / record length
  • if there is inadequate memory, this can result in truncated signals or loss of detection of signal events causing apparent artefacts
    • a solution is to reduce the time duration for the display
    • sample rate and memory is split between all the turned on channels (irrespective if they are connected or not - so switch off unused channels)
    • progressive mode tweaks use the computer's memory and can help mitigate this issue
    • eg https://www.youtube.com/watch?v=uV0djQUatgQ memory of 4Ksamples or even 8Ksamples were inadequate for a crankshaft sensor esp. in 2Ch mode - you can get automotive Pico scopes such as the 4425A with 2.4M samples which easily resolves this
  • the record length (the total duration of the sampled signal) directly determines the frequency resolution or bandwidth of each FFT bin. Longer record lengths mean narrower bins and finer frequency resolution, allowing clearer separation of closely spaced frequency components.
  • if the input signal duration is shorter than the full record length, the FFT peak amplitude decreases proportionally because the effective duty cycle of the signal within the window is lower. For example, a signal occupying 80% of the record length will have an FFT peak at about 80% amplitude of a full-length signal
  • limited record length can cause spectral leakage, where signal energy “spills” into adjacent FFT bins, causing broadened and biased peaks
  • choosing an optimal record length helps maximize frequency resolution without overextending bandwidth limits, reducing peak bias and enhancing spectral accuracy
• maximum input voltage
  • many scopes have a max. input voltage less than 200V peak, so if connecting 240V AC, you will need to be using a 10:1 probe with max 300V rms specification so that only 24V AC goes into the scope
• trigger options
  • a trigger is used to capture a stationary image of the waveform after the trigger specified has been met (eg. voltage > 10.4V)
• display options
  • can you set the scope to account for the probe's scaling switch setting or other parameter such as pressure to voltage conversion
• FFT display
  • converts a measured signal from the usual time domain (voltage versus time) into the frequency domain (amplitude versus frequency), allowing visualization and analysis of the signal’s frequency components
  • helps identify specific frequencies, harmonics, noise, and distortion that may not be easily detected in the time-domain view
  • unfortunately most of the handheld cheaper devices only display the wave form but do not give any actual frequency values so they can only give you a qualitative view
  • see also maths: Fast Fourier Transforms
  • very handy for analyzing audio output from synthesizers, etc
  • NB. this is very different to frequency response analyzers which inject a controlled, swept-frequency signal into a system and measure its output at each frequency, generating accurate Bode plots (gain and phase vs. frequency)
• IQ analysis
  • oscilloscopes can generally display I (in-phase) and Q (quadrature) components separately.
  • those designed for RF and vector signal analysis, have features that allow them to capture, display, and analyze IQ signals by showing the I and Q waveforms on separate channels in the time domain
  • oscilloscopes with XY mode or vector signal analysis capabilities can represent IQ signals spatially as constellation or vector diagrams, which visualize the relationship between the I and Q components together
  • some mixed-signal oscilloscopes include digital downconverters to extract IQ data from RF signals for detailed analysis and demodulation. This functionality is common in advanced lab-grade oscilloscopes made for communication signal testing and software-defined radio work
• other scope functions
  • math functions
• probes
  • if you are going to be measuring AC systems or devices connected to mains AC, strongly consider using differential probes which isolate the grounds to avoid accidental short circuits due to connecting the ground to a non-ground part of an AC device

• these require a computer and software to operate via USB
• Pico models
  • if you want to use Pico Automotive Software you need to have a supported model - see https://www.picoauto.com/downloads
    • newer models have PicoBNC+ which is a modified BNC interface with a digital connection for plug and play probes so the software can detect which probe is attached and provide power to the probe instead of needing batteries
    • Pico P4225A automotive 2-ch scope starter kit ~$AU1900 and a 0-600A current clamp transducer is ~$AU300-500 depending upon model
      • 20MHz; 12bits; 400MS/s;
      • eg. https://www.autoequipment.com.au/p4225a-picobnc-2-channel-automotive-oscilloscope-scope-only
    • Pico P4425A is a 4-ch version
• Hantek 6074 Automobile Oscilloscope
  • 4ch; over 80 types of automotive measurement function (Ignition Action/The Sensor/Bus Diagnosis/Performer/Startup&Charge);
  • USBXI, easy to operate. 1GSa/s real time sampling rate, 2mV-10V/DIV high input sensitivity and large input range, 70MHz high bandwidth
  • Windows only;
  • various options: https://www.aliexpress.com/item/1005006021982326.html

• Uni-T MSO3054X
  • 4ch; 500MHz; 5GSa/sec;
  • ~$AU6000
• Infiniivision 1000 X-Series Keysight DSOX1204G/200-AU
  • 4ch; 200Mhz; 1GSa/s; 200,000wfm/s; 1m points; 20MHz wave generator;
  • I²C, SPI, UART/RS-232, CAN, LIN standard serial protocol analysis
  • customizable AM, FM and FSK settings; FFT;
  • ~$AU4800
  • https://www.youtube.com/watch?v=d58GzhXKKG8
• Siglent Technologies sds1204x-e 4ch
  • 200MHz; 4ch; Super Phosphor tech; 1 GSa/s with 14 Mpts record (less if more than 1 channel in use)
  • serial bus decoding for IIC, SPI, UART, CAN, LIN bus types are included; HDTV; 1 million points FFT math function;
  • 100,000wfm/s (400,000wfm/s in sequence mode); low noise;
  • ~$AU1250 (2ch version is ~$AU760)
• Rigol DS1054Z
  • a very popular scope
  • 50MHz but firmware can be hacked to get 100Mhz bandwidth
  • 1 GSa/sec; 24Mpts record;
  • ~$AU1100
• Rigol MSO5000 series
  • 9“ touch screen; 70-350MHz (depending on model); 4ch; 16 dig ch; 8GSa/sec; 200Mpts (opt); 500,000wfms/sec; opt. 25Mhz signal generator;
  • power analysis; protocol decoding;
  • ~$AU2400 for 350MHz 200MPts with signal generator;
• Rigol MHO900 series
  • MHO934 4CH 350MHz 12 bit at 4Gs/s, 2 signal generators, $US999 - see https://www.youtube.com/watch?v=6lBU4NwmY7s
• RIGOL MHO/DHO5000 series
  • 2025 models; large touch screen;
  • 0.5-1GHz depending on model; 4GSa/sec; 1million wfrms/sec; 500Mpts memory depth; 12bit vertical resolution; low noise floor; optional battery pack;
  • power quality analysis; ripple analysis;
  • protocol decoding (RS232/UART/I2C/SPI/CAN and optional for others) of 4 BUS decoding modules on analog ch inputs;
  • MHO5104: 4 BCN inputs; 4 digital inputs D0-15; 2 grounded outputs max 42V; opt. 50Mhz arbitrary waveform signal generator; frequency response Bode plots;
  • DHO models have 4 r 8 BCN inputs but no digital inputs and ?no signal generator / Bode plots;
  • https://rigolna.com/products/digital-oscilloscopes/dho-mho5000/
  • https://www.youtube.com/watch?v=liHVk0E3wTA
• OWON XDS3204E
  • 4ch; 100MHz; 14bits?; 8” touch screen; 70,000wfm/s; 1 GSa/s with 14 Mpts record; 1mV-10V/div; RS232 decoding; single trigger;
  • ~$AU1400

• see Fnirsi DPOS350P oscilloscope / signal gen / SA / freq resp analyzer
• if you want to capture an event longer than 0.2 secs you will need to manually pause it or use a video camera as triggering is not available for time periods longer than 20msec/div
• scope: 2ch; “350Mhz bandwidth” limited by hardware to 150Mhz/50MHz; 1GSa/sec; 50,000 wfms/s; 8-16bit resolution; 60Kpts memory; simple FFT support; trigger; X-Y; 2mV-20V sens; 400V high-voltage input with overvoltage protection;
  • 1x/10x/100x probe setting; two 350MHz Probes with 1x/10x switches;
• signal gen: sine wave 0-50MHz; others up to 3/5/10MHz; max 5V; can output a captured wave form up to 3MHz;
• frequency response analyzer up to 50MHz
• spectrum analyzer: 4K-32K length; 200kHz-350MHz; waterfall; signal strength is in dBmV not dBM;
• 2hr 8000mAh 29.6Wh battery 18W QC 2hr fast charging; 10W 2.4A consumption; 7“ 1024x600px touch screen;
• https://www.aliexpress.com/item/1005008897925504.html ~$AU375

• inadequate trace buffer
• no oversampling resulting in lots of aliasing
• inadequate sensitivity such as only 50mV per division
• inadequate bandwidth
  • many state 50-100MHz but are only reliable below 20MHz
• noise in the system such as due to cheap power adapters
• buggy software
  • trigger point values change when you zoom in instead of remaining constant and their display changing according to zoom level
  • may display incorrect wave forms in certain situations or give erroneous measurements
• see https://www.youtube.com/watch?v=sd_mHf-cwIA Fnirsi-1014D issues

• 2.8” display
• max 400V;
• oscilloscope: 2ch 180MHz, 20MHz hardware limit, 500MSa/sec, 50000wfm/s, 120kpoints, DC/AC coupling; 5ns-50sec; 40mV ~ 80V(1X); FFT; X-Y; auto/normal/single trigger; wave capture;
• Matching 200MHz Probe (1X & 10X）
• 20MHz signal generator;
• ~$AU190

• compact 3.5“ 480×320 display - not touch screen; 2 side control dials to adjust A and B channels;
• 2ch; 50MHz; 50MSa/sec; 8 bit; MCX ports not BNC;
• XY; FFT;
• 1500mAh battery;
• https://www.youtube.com/watch?v=kcteTLT89h4
• ~$AU110

• compact, tiny 1ch scope with a signal generator but the interface is a bit clunky as you would expect for such a small device
• great for doing signal analysis to find faulty components in devices as you can have the screen near where you are probing
  • see https://www.youtube.com/watch?v=Vox-OEr2OfM using a tiny cheap FNIRSI DSO-510 to find the faulty transistor using an RCA T-piece to connect signal generator to the stereo RCA cables which connect to the amp RCA inputs

• ultra-compact hand size single channel very basic oscilloscope with 2.4” screen;
• 200kHz bandwidth; 2.5MSa/sec; auto/single/normal trigger modes; up to 400V;
• 80kHz, 5V PWM square wave signal generator with adjustable duty cycle
• 5hr USB-C rechargeable battery; 2 probes including high voltage probe;
• ~$AU40

• 4.3“ screen; 5ch with 1MHz bandwidth, specializing in low-frequency signals (such as audio, sensor signals, industrial control signals)
• 3MHz sampling for 3 or less channels, 1.5Mhz samle for 4 or 5 ch;
• 2000mAh battery; max voltage 20V pp; XY; trigger; up to 1kHz signal gen;
• USB and opt. WiFi version - allows PC recording up to 90hrs (8M per ch)
• https://www.aliexpress.com/item/1005009539539512.html ~$AU120

• generally have very basic limited oscilloscope: no BNC inputs - multimeter probes are used instead; 5MSa/sec; 1MHz bandwidth;
• see multimeters

• these generally have very basic oscilloscopes: 1MHz bandwidth; 5MSa/sec; max. input 1000V; 2.5microsec-10s/div; 30mV-500V/div; only automatic trigger mode;
• see multimeters

• Pico BNC and BNC Pico+ probes
  • https://www.picotech.com/accessories/current-probes
• passive probes
  • these are the main one supplied with oscilloscopes
  • usually have a switch for 1x and 10x (the 10x reduces the voltage sent to the oscilloscope by 10x so if testing a 200V it sends 20V to the scope)
  • generally have limited bandwidth such as 350Mhz but this may change depending upon attenuation switch setting:
    • may only have 6MHz bandwidth at 1:1 but 200MHz at 10:1
• active probes
  • similar to passive probes but are usually battery operated and allow much higher bandwidths eg. 3GHz and have a lower input capacitance of < 3pF
  • voltage input range is much lower at 20-30V depending upon model
  • input impedance is usually around 1MOhm
  • often have a fixed 10x attenuator
  • mainly for precision analysis of low voltage signals on circuit boards and often include special probe adapters which can be soldered onto the PCB
  • very expensive usually $US1000 or more
  • eg. Euler Precision eSAP-30 3GHz Active Probe
• current clamps
  • basic low frequency clamps:
    • Hantek CC650 400Hz for high currents up to 650A 30mm clamp - best for car cranking analysis, etc ~$AU110
    • Hantek CC65 400Hz for lower currents and higher precision designed for smaller wires ~$AU110
  • expensive high frequency clamps
    • allow analysis of much smaller time scaled events and higher frequency signals
    • eg. detecting the initial power surge when a power adapter is turned on
    • Micsig CP2100A
      • measures AC and DC current up to 100 Apk (70.7 Arms) with bandwidth up to 800kHz; requires USB power; 13mm clamp; ~$AU500
    • Micsig CP2100B
      • max 100Apk, 70.7Arms (DC+ACpk); bandwidth up to 2.5MHz, Resolution: 0.1V/A (10A), 0.01V/A (100A); requires USB power; ~$AU600
    • Micsig CP503B
      • max 50Apk, 30Arm; 50MHz bandwidth; 4mApp noise; rise time < 7nsec; < 30nsec delay; 5mm clamp;requires USB power; ~$AU1550
    • Micsig CP1003B
      • max 50Apk, 30Arm; 100MHz bandwidth; 4mApp noise; rise time < 3nsec; < 30nsec delay; 5mm clamp;requires USB power; ~$AU1550
    • NB. the following Mealu probes come with EU AC power adapters
    • Mealu ICP5050
      • 20A DC to 50A peak AC; bandwidth of 50MHz and ±3% accuracy; ~$AU1430
    • Mealu ICP9150A
      • 150A/12MHz; ~$AU4500
    • Mealu ICP9300A
      • 300A/DC～6 MHz; ~$AU5300
    • Mealu ICP9500A
      • 500A/DC～5 MHz; ~$AU6400
• differential probes
  • isolate grounds for safer use in AC connected devices
  • Mealu ICTP9511
    • X and Y BNC outputs for analyzing electronic components - each type has a different X-Y pattern; AC power adapter required and included (EU); ~$AU275
    • two attenuation ranges 1/50 and 1/500 with the Maximum measurable differential voltage are 130V (DC + peak AC) and 1300V (DC + peak AC) accordingly.
    • https://www.aliexpress.com/item/1005003949156296.html
• pressure transducers
  • Jinhan JH APT-100
    • [https://www.aliexpress.com/item/4001198287616.html]]
    • looks similar to the Picoscope WPS500X Transducer but is a lot cheaper
  • Picoscope WPS500X Transducer
    • https://www.picoauto.com/products/pressure-sensors/wps500x-overview
    • designed for automotive work
    • see https://www.youtube.com/watch?v=4YAfPwW02dc

• you need a clamp meter (either combined clamp meter/oscilloscope or separate transducer and oscilloscope)
• ensure the ignition/fuel pump is disabled
  • eg. remove the fuse marked “ECU” or “FUEL PUMP” if present, and confirm non-starting
• place the clamp around the start motor feed wire
• set trigger on the oscilloscope so that it captures the 1st few seconds of starting the cranking
• set Y axis scale to allow for up to 500A
• set X axis scale to display several seconds
• crank the motor by turning ignition key to Start as per usual (the motor should crank but not start if the ignition and fuel pump fuses have been removed)
• assess the oscilloscope:
  • there should be a transient initial very high current perhaps 400A to the starter motor to overcome the inertia of the flywheel (which will usually drop the battery voltage from over 12V down to ~8V), then it sends spikes of around 100-150A (battery voltage will generally be down to 10V in this stage) to the spark plugs
  • the higher the current spike, the more compression pressure is being generated.
  • a low current spike compared to other spikes would suggest leakage from the cylinder and failure to achieve adequate compression (eg. worn piston rings)
  • each spike represents one piston in sequence
  • a failure of a spike in the sequence on an oscilloscope doing a relative compression test may be due to a faulty spark plug or a fault in the starter motor such as a solenoid tripping for that cycle

• absolute pressure measurement of cylinders using special screw in cylinder pressure transducers
• assessing coils, distributor, etc
• troubleshooting electronics and sensors
  • trap when errors occur and analyze whether sensor voltages are outside design specification and triggering a malfunction - requires connecting the sensor wiring to the inputs and best combined with a car computer error software app connected to the car's computer system

• the signal from the ignition coil should have an initial drop to 0V then slow climb as coil charges, then a ~400V surge which is sent to arc the spark plug, and then a downward slope (the seat of the “chair”) as the spark plug fires, then a residual wave as it returns to normal voltage.
• easy way induction method: place a coin on the coil and put the +ve probe onto the coin, neg to GND and then start engine
• more expensive easy way: buy a coil transducer probe that is designed to be placed on the coil
• the capacitative method way: buy a capacitative probe designed to clamp around the ignition coil cable such as a Hantek HT25
  • if the cable is faulty it could fry your scope so check the cable first for high voltage leaks and replace cable if there are any
    • check for high voltage leaks clamp one end of a probe wire to the GND and use a probe on the other end (not your scope probe!) to run along the outside of the wire and check for sparks which indicate a high voltage leak
  • different cables may give an inverted signal
• harder way: pin the primary coil wire using probe at 10x as voltage can reach 400V - DO NOT ATTACH to SECONDARY as the 20,000-30,000V WILL BURN OUT your scope!
  • https://www.youtube.com/watch?v=HZRm-QzHBk0

• analyzing waveforms from high-voltage batteries, inverters, and traction motors to detect irregularities and performance issues
  • checking battery charge/discharge cycles with high accuracy to ensure cell balance and state-of-health assessment
• testing sensors and actuators used in battery management, drive units, and auxiliary systems
• diagnosing communication networks (e.g., CAN, LIN buses) crucial in EVs for coordinating systems and transferring diagnostic data
• EV traction inverter and motor system analysis, optimizing and troubleshooting energy transfer and conversion
• display of real-time waveforms of bus signals, enabling detection of physical issues like noise, voltage drops, skew, bus shorts/opens, and intermittent connection faults

• see radio basics
• oscilloscopes used for radio analysis should have:
  • significant bandwidth (hundreds of MHz to several GHz), probe’s bandwidth should match or exceed the oscilloscope’s bandwidth, and rapid sampling rates to accurately capture and analyze high-frequency RF signals
    • for HF radio analysis (3–30 MHz), an oscilloscope with at least 30 MHz bandwidth is the bare minimum, while 45–60 MHz is recommended for accurate waveform capture—a 100 MHz scope offers ample headroom for harmonics and complex modulation. For VHF radio analysis (30–300 MHz), select an oscilloscope with bandwidth 1.5–3 times your highest signal frequency; for example, a 150–300 MHz scope is suitable for signals up to 100 MHz, and a 500 MHz or higher scope is needed if measuring frequencies at the upper end of the VHF band or capturing harmonics
  • additional features, such as advanced triggering, FFT analysis, and digital recording
    • for applications requiring reliable VHF FFT results, dedicated benchtop oscilloscopes with sufficient bandwidth and sampling rates are preferred over low-cost USB models
• can show waveforms of radio frequency (RF) signals, letting engineers inspect modulation characteristics (AM, FM, PM), distortion, envelope, and signal integrity
• by calculating the period and frequency of signals, oscilloscopes help verify oscillator performance and monitor RF carrier stability
• with FFT capabilities, modern oscilloscopes allow users to analyze spectra of RF pulses and carriers, similar to what spectrum analyzers do. This is vital for examining modulation processes, harmonics, and identifying sources of interference
• can trace signals through radio circuits, aid in gain measurements, detect faults, and help isolate problems in oscillators, RF amplifiers, mixers, detectors, and audio stages
• time-domain features enable precise measurement and triggering on radar and pulsed radio signals. Oscilloscopes can analyze pulse width, repetition rates, and envelope variations critical for radar and communication systems
• checking if a local oscillator in a radio receiver is working by probing for expected oscillation waveforms
• analyzing and measuring signal modulation to assess transmission quality and antenna performance
• comparing input and output waveforms for power gain measurements across amplifier stages
• monitoring pulsed RF signals in radar systems, evaluating modulation strategy and signature via time-domain and frequency-domain displays
• measuring transmitter radio output power:
  • WARNING: ensure the voltage output will not exceed the max. voltage input for the scope otherwise it may get destroyed!
    • for Ham radio operators, see https://www.youtube.com/watch?v=2D83xp3H5Bo
  • if measuring a transmitter radio power output, need to use a T-adapter with a 50 Ohm dummy load on the dummy side of the T to avoid reflected power back into the radio and potentially damaging it.
    • Power in W = (rms voltage)²/actual resistance of the dummy resister
    • power in W = 10^(dBm/10) x 10^-3
    • NB. for a AM radio transmitter such as CB radio, the un-modulated carrier wave power is usually 30-60% of the max AM modulated power output of the radio
    • a 4W radio may give ~11Vrms / 2.4W when unmodulated and ~14Vrms / 4W at peak modulation (loudest sound being sent)
    • see https://www.youtube.com/watch?v=tQOE69iD0a4
• tuning an antenna
  • https://www.youtube.com/watch?v=y4Zt_LJX1Tc
    • impedance of antenna using his circuit = 50 Ohm x measured voltage / (input voltage - measure voltage)
    • where input voltage has a zero phase component as this is the reference signal from a signal generator
    • and measured voltage is a complex number = voltage + phase shift in nsec time delay (time delay as compared with input voltage signal)
      • measured phase delay in degrees = measure time delay in nsec x signal frequency in MHz x 360
      • this voltage in polar coords of V + degrees can be converted to rectangular coords of V + j for easier calculation of the above formula
• measure length and impedance of coax
  • https://www.youtube.com/watch?v=Il_eju4D_TM
  • uses speed of signal in coax based on a typical coax cable velocity factor (VF) of 0.66 (range 0.6-0.85) of speed of light in free space of 11.8” or 30cm/nsec (this VF is related to the dielectric constant) which gives 7.79“/nsec speed in coax
  • using a T on the scope input with one side coming from the signal generator giving a square wave pulse and the other side connected to your open ended coax
  • the signal on the scope will have a step before the voltage continues to go up from the reflected pulse coming back from the end of the coax
  • the twice the length of the coax is then simply the width of this round trip step in nsec x 7.79”/nsec - so this needs to be halved to get length of coax
  • you can measure the actual VF of your coax by doing the above and input the known length of the coax into the equation and have VF as the unknown https://www.youtube.com/watch?v=TpIIftvQPFM
  • you can measure the impedance of the coax by attaching a variable resistor to its end and adjust the resistance until the scope shows loss of the step displayed above and then the impedance is that resistor value as measured by an ohm meter

• DIY single lead ECG
  • https://www.youtube.com/watch?v=1EGhAKdqAag uses a 3.3V powered AD8232 (he used a 9V battery and a AMS1117 3.3V voltage regulator)
    • convert Hz to beats per minute

• get a BNC to 1/4“ audio plug for each channel - each channel will be mono inputs - voltage range is usually 0-5V
• set scope to AC signal for audio, trigger to normal, trigger source to your input channel
• see https://www.youtube.com/watch?v=A_LtC6HI5YI using a Korg NTS-2 scope
• https://www.youtube.com/watch?v=xoqf4ZMk4bs&t=161s