Tag: device analysis

#0028: Game Boy Advance SP audio/power port analysis

Otto

#0028: Game Boy Advance SP audio/power port analysis

Preamble

This article consists of various labelled pinout diagrams. They specifically feature: the charge port, and accompanying plugs, of the Nintendo Game Boy Advance SP (GBA-SP) portable games console. These diagrams will also include annotations on various notable details regarding these pins and their functionality. Additionally I will also feature some of my personal commentary on the port in general.

It should be noted that the information gathered for these diagrams is collected first hand, without the use of any official reference materials. As such I can only discuss the functions of the various pins that I have personally identified and mapped out. Whether or not this port or any pins within have any additional functionality beyond this is unknown to me. Since I have only identified this port as being used for either power ingress, or audio output: I will henceforth reference it as the “audio/power port”.

GBA-SP

Note: I feature this image set in order to establish a basic reference for the GBA-SP: in the case that the reader is not familiar with this device. The GBA-SP only has two ports on it. These are the audio/power port (on the left of the images), and the COMMS (or communications) port (on the right). This article only features details on the audio/power port.

Notables:

  • The audio/power port has six pins within it. Four on the under side of the plastic support, and two above it.
  • The port also has a retaining spring that looks like a pin. This clip holds any inserted plugs in place. It is located between the two top pins, on the centre part of the plastic support, that juts out toward the inner wall of the socket.

GBA-SP charger and plug pinout

Notables:

  • There is a pinout diagram (or legend) of the charger’s plug on the charger’s plastic housing.
  • Despite the unique plug, the GBA-SP actually uses a very basic AC-DC power-supply that provides 5.2 volts DC @ 320mA.
  • 5.4 VDC is the charger’s measured open circuit output voltage. I assume it drops to ~5.2V once loaded.
  • The output power (both voltage and ampere) is within/around the USB standard. Nintendo could have arguably used a standard mini-USB port at the time (2002) to power the device instead.

GBA-SP audio cable plug pinout

Notables:

  • It is keyed for stereo sound, having two different audio channels that then share a return line.
  • The audio ground (or return, or drain) is not electrically connected to the device ground.
  • When inserted, the plug shorts the audio switch pin to ground
  • The only pin missing from the audio plug is the pin that corresponds the device’s V+ inlet pin.
  • Dedicated article: #0025: Modifying a pair of GBA-SP earphones into an aux audio dongle

GBA-SP audio/power port pinout

Notables:

  • Pin: Audio channel (right): carries the positive signal for the right channel (of stereo audio).
  • Pin: Audio channel (left): carries the positive signal for the left channel (of stereo audio).
  • Audio ground: functions as a return for both the right and left audio channels.
  • The GND pin, as well as the metal sheath of both the audio/power port and the adjacent communication port are all electrically connected.
  • The Audio switch pin has a floating voltage of 0.5 volts.
  • To activate the Audio switch: tie it to GND.
  • Pin: V+ is for the 5.2 VDC input from the charger.

Testing the audio switch on the GBA-SP

control test with an audio plug
test by manually shorting the audio pin

System freeze demonstration

While I was recording the testing of the audio/power port on the GBA-SP I came across a system freeze. Initially I placed it here because I thought it might be relevant to the audio/power port in some capacity. However after I had some time to think about what might have caused this system freeze, I have come to the conclusion that in all likelihood this freeze was caused by me putting pressure on the game cartridge as I inserted the audio plug into the console.

This likely then caused the cartridge to move slightly, but enough to break continuity between it’s pads and the console’s pins. Perhaps one or more of the GBA-SP’s pins moved onto a more insulated or corroded section of the cartridge’s pad(s). A section that is insulative enough that it either blocked or damaged the signal integrity beyond interpretation.

The main reason why I think this is the case, is because the audio/power port doesn’t deal with any data outside of audio signals. Certainly nothing that could cause a system freeze in my opinion. However what has caused multiple freezes in the past is tampering with the game cartridge while it is powered and in use.

Thoughts on Nintendo’s anti-consumer product design

In the previous GBA-SP dongle article I went on something of a rant on Nintendo’s anti-consumer design with regards to this particular product. In order to avoid rehashing those same points, I’ll keep my thoughts here concise, and offer them more as an addendum to that gassy rant.

To cut to the point. Yes I still think that the removal of the 3.5mm audio jack during the design iteration from the GBA to the GBA-SP was an anti-consumer gesture. Additionally I think this unique GBA-SP plug and socket design is woefully unnecessary; at least from a technical perspective.

As far as I can tell: Nintendo simply mashed together the functionality of the generic 3.5mm audio jack, and of the standard Mini-USB connector available at the time (~2002). They blended these two standards into their own bespoke plug and socket design. A proprietary design in which they can control the availability and price of. At least for the critical time period after the public product release, where there’d be the highest demand for accessories like this. Accessories, that they could then price gouge their customers on, with no competition (i.e. no legitimate alternatives).

The reason why I believe this to be the case, is that without the motivator of maximising profits: this design decision of creating proprietary alternative designs for already existing standard open designs makes little sense. Let us consider that if instead of this (immediate) profits driven motivator, the main motivator was to create a versatile and endearing product. One that will be usable long into the future due to the sheer availability of parts, and supporting accessories. Such as USB related componentry.

If they really wanted to make the best product they could for their customers: then I believe there is little reason not to use a Mini-USB port to power the device, and a 3.5mm audio socket for sound. This is especially evident due to the fact that the Mini-USB standard could already satisfy the GBA-SP’s power requirements of 5.2 volts at 300 milliamperes. Perhaps there were some licencing issues with regards to that idea that convinced them otherwise. It may even be the relative fragility of the Mini-USB socket that convinced them not to use it. I do believe that Nintendo’s proprietary port is more rugged than the Mini-USB port. I’ll give them that. I will also say that this is also one of the few instances where a “think of the children” argument may actually have some merit. Kids are generally destructive with toys. However I doubt that was the motivator here, at least not the main one.

Closing thoughts

I wanted to create this article initially for referential purposes, if not just for the sake of completeness. Prior to this, I wrote an article on creating a GBA-SP audio cable. This prior article featured a pinout diagram of this same port’s respective plug (audio version). However this diagram only featured labels relevant to the plug’s audio cable.

I didn’t even compare this information to their counterpart pins on the GBA-SP (or the charger’s plug). This is because I did not need to in order to achieve the stated goal of creating an audio adapter. If I did compare the pins, I would’ve found out that the lower “closed loop switch” pin (as I put it): is actually the main ground pin; and that “closing the loop” actually meant pulling the 0.5 volts from the top pin to ground. Although its essentially two different ways of saying the same thing: the latter method gives a more informed picture of what is actually going on. That is all this article is really for at the end of the day: to get a better idea of how that particular port works by using first hand experimentation and some deductive reasoning.

Anyway, I hope this article proves itself useful to you.

Thanks for reading.

Links, references, and further reading

https://www.tinkerersblog.net/0025-modifying-a-pair-of-game-boy-advance-sp-earphones-into-an-auxiliary-audio-dongle/
https://en.wikipedia.org/wiki/USB_hardware#Mini_connectors
https://en.wikipedia.org/wiki/Game_Boy_Advance_SP

#0015: Device analysis of an unbranded LED dynamo torch

Otto

#0015: Device analysis of an unbranded LED dynamo torch

Preamble

It’s rather hard to provide a useful review of an unbranded product such as this. Since it has no brand, and no model to specify; we can only identify this particular device by it’s general appearance. Unfortunately this can be an issue when it comes to stating anything definitive about the product. This is due to the unregulated variations and derivatives on the market. In other words, just because two of these unbranded devices are outwardly identical, doesn’t necessarily mean that the components (or configuration there of) are also going to be the same. Heck, we don’t even know if any two different units were made by the same OEM (Original Equipment Manufacturer). Consequently, your mileage may (and probably will) vary if you pick up one of these dynamo torches. I can only show you what I have in front of me; and I have a sample size of two.

Device Demonstration

Device internals

Schematics

Torch A

made using https://www.digikey.com/schemeit/


Torch B

Key:

L1: 5 mmØ through-hole LED (white)
L2: 5 mmØ through-hole LED (white)
L3: 5 mmØ through-hole LED (white)
R1: 5.1 ohm resistor
S1: two-state toggle slide switch
V1: dynamo (AC source)
B1: [x3] AG10 / LR1130 button cell battery

Possible modification

  • rectifier and capacitor on the dynamo circuit

Key:

DB1: Diode Bridge
C1: capacitor

I think that perhaps some kind of rectifier followed by a capacitor on the dynamo circuit will provide the parallel LEDs with a more constant voltage. Allowing it to stay on with a constant light intensity for a little longer, at the cost of a few initial revs without any light output as the capacitor charges. Is it worth the effort? Not especially. It might just help prevent the sudden light dropout. I’ll need to test it out myself before I say anything definitive here.

As for the rectifier, I would recommend a full-bridge rectifier using four diodes for maximum efficiency. That is if there’s space for it. This is because this configuration inverts the AC negative voltage into positive, before passing it onto the smoothing capacitor. Alternatively, a single inline diode will simply cut the AC in half by passing only the positive voltage. It’ll do the job, but at the loss of the negative voltage of the AC. Although, this is lost anyway at the LEDs, since they’re diodes. With this use-case, I think we need all the efficiency we can get, and a full bridge rectifier may even make the device function a little better. Like I said it needs proper testing, that’s why I stated this as a “possible modification”, rather than my usual “recommended modification”.

EDIT (2021-02-04): On further thought, any benefits of rectifying the dynamo AC will probably be negligible. I believe this is the case due to the low voltage provided from the dynamo (approximately 2V AC) coupled with the forward voltage drop that will occur within the diodes themselves.

The example diodes I have (namely 1N5818) have a really small forward voltage drop of 0.45 volts at 1 ampere. Even this miniscule drop will have a notable effect on any resultant DC.

web link: https://www.bitsbox.co.uk/data/diodes/1N5818.pdf

datasheet_1N5818_bitsboxDownload

Still I still think the idea of rectifying a dynamo’s AC to DC would be worth while if for no other reason then to make a generally more useful form of power. Unfortunately, for a dynamo of this output, it’s just not worth it.

Dynamo AC generation demonstration

Gear array and dynamo

A1: Spur rack: 24 mm w/ 11 teeth
B1: Spur gear: 8.5 mmØ w/ 10 teeth
B2: Spur gear: 41 mmØ w/ 81 teeth
C1: Spur gear: 7 mmØ w/ 12 teeth
C2: Latching spur gear: 2 pivoting teeth
D1: Internal spur gear: 26 mmØ (inner diameter) 32 mmØ (outer diameter)

(Please note: when two gears have the same gear letters, it means that the gears are connected.)

Dynamo:
24 mmØ toroidal (doughnut) magnet (with 4 Norths and 4 Souths)
coil consists of:

  • dynamo core (magnetic conductors)
  • a 920 cm length of 0.1 mmØ gauge copper wire
    (wrapped into a coil of ~276 revolutions)

Please forgive any inaccuracies in naming convention for the gears, this is the first time I have actually paid any attention to the subject of gears in general, and it appears to be a deeper subject than initially expected with quite the learning curve involved. The “latching spur gear” and “internal spur gear” are the ones where I hazard a guess as to what they might be called, this is because at the time of writing I was unable to find a named example of what I was looking at. It can be difficult to find something when one doesn’t know the keywords to search.

Gear system in action

Pushing force on the handle moves the spur rack against spur gear B1. B1 then rotates clockwise. This in turn rotates the conjoined spur gear B2 clockwise. B2 interfaces with spur gear C1, and rotates spur gear C1 counter-clockwise. Which in turn rotates it’s conjoined latching spur gear (counter-clockwise).

The swivel teeth within the latching spur gear are designed to lock into the teeth of the internal spur gear D1. Although this happens only when they rotate counter-clockwise within D1. In doing so they rotate D1 and it’s toroidal magnet. This rotation causes a flux in the local magnetic field. This is picked up by the magnetic metal of the “dynamo core” and transported via this core to the copper coil winding. Where it induces an alternating current that powers the LED lights.

Once the handle is fully pressed in, with the spur rack (A1) at the end of it’s track. The operator’s pressing force is removed. At which point the spring in the handle pushes the handle back out; and forces the spur rack to move back to it’s start position. In doing so it rotates spur gear B1 counter-clockwise this time, this rotation is passed on to spur gear B2. Which rotates spur gear C1 clockwise. This rotation is passed to the 2 tooth latching spur gear C2. Which in turn spins clockwise freely and allows the gear system to reset position. Then the process repeats as the operator pushes on the handle. And so on.

The device as a consumer product

Build quality

This is probably the cheapest dynamo torch on the market. If not in price, then certainly in build quality. The main body of the torch is made up of two separate mouldings that sandwich together. This configuration clips into the grey plastic ovoid that houses the LEDs, batteries, and the light guide/reflector. Add to this one or two (depending on version) small self tapping phillips screws to keep the device together.

The phillips screws for the housing are set into thin moulded standoffs that seem prone to either splitting at the screw thread or cracking at their base. The cracks on the base of these standoffs I believe are caused by the general mechanical stress incurred by the gear and spring system. Both in action: when the dynamo mechanism is being used, with the spring loaded handle being vigorously pumped back and forth; and at rest, because the spring that pushes the handle back out puts a constant stress on the gears that are set into these flimsy standoffs.

I have had these two torches in safe storage for a few years, I was surprised to find out that one of the two had broken it’s standoffs, well off. Considering my storage solution (think sealed plastic tub in a garage), this may have been caused if not exacerbated by temperature variations, in addition to the stress of having a coiled spring pushing against them. But basically, I put the thing away fixed, and found it broken. Considering that one of the use-cases the online retailers advertise this thing for is camping, I don’t think that the temperature swings of the mild british weather should have caused this.

Something positive. The internal components I generally have little problem with; from the LEDs, to the Dynamo, and nylon gears. They are all very inexpensive components, but there is nothing especially wrong with them. They are all basically fit for purpose. Even the dynamo, although unfortunately, it’s delicate hair thin wires extend out the dynamo coil and into the device proper: towards the switch and LEDs. This makes the device far more likely to suffer a breakdown, as these wires are far too thin and delicate to be used for general device circuitry. Especially when in the presence of an unshielded gear-system. Look at the pictures to compare the dynamo wire (~0.1 mmØ) to the LED (~0.4 mmØ) or switch (~0.5 mmØ) terminals to understand just how thin the dynamo coil wire is. Please note: inaccuracies in recorded measurements are due to the pictured calipers used … and me.

False advertisement claims

I have seen this torch (and it derivatives) in multiple online stores. I have also seen a lot of false advertising around this product across multiple vendors. Including Ebay, AliExpress and especially Amazon. This is predominantly due to the seller’s lifting the product descriptions from each other, in some cases they’re literal copy-pastes.

There are many claims on these store pages that made me chortle. These included: “High tech ultra bright LEDS” when referring to the 3 bottom market 5mmØ through-hole LEDs; or the sentence “perfect for outdoor use” when describing an electronic product that is about as watertight as the average kitchen sponge.

Since these claims made are subjective, you can’t say that they are technically wrong, because that’s just like your opinion man. These are (in my opinion man): just examples of product puffing or marketing wankery. Something that I honestly have come to expect at this point in my life. Whenever I go to buy something, I will inevitably have some to sit through at least some marketing bullshit, because apparently every single product ever made, is as great a sliced bread, and should get you as excited as the second coming of our lord and saviour. Or else there is clearly something wrong with you.

Moving on. Something else that I have come to expect, and let’s be honest here – enjoy: is Chinglish. And there are some great examples of this within these product descriptions. My favourite is “Works on a new technology of pressing handle with your hand.” Hey, it made me smile. Here’s another doozy for you: “LED torch adopt advanced technology of LEDs emitting level of 3 fluorescence tube”. What the actual fuck are they trying to say?! If internet scholars ever decrypt this product claim, you can probably safely bet that is it some form of bullshit.

Which nicely brings me to the real issue that I have with these product ads. It is the genuine examples of outright falsehoods. The main two claims that I have issue with, are: 1) That the dynamo action charges the batteries, and 2) That the product doesn’t include batteries in the first place.

For the first example I have an ebay advert that uses the keyword “charge” in it’s description and makes mention of the 3 disposable AG10 coin batteries that come in the unit. Although it doesn’t mention that they are single charge disposable units. Hence the assumption that the average consumer is likely to make is that the dynamo charges these batteries. Another amazon ads states the claims “No batteries required, Eco and rechargeable”, to make the customer think that it comes with some kind of componentry that either enables the device to charge without batteries (e.g. capacitors), or that the device comes with built-in rechargeable batteries.

Unfortunately neither are true. A cursory look at the above schematic for either unit A or B will show you that at no point does the dynamo charge the batteries. They are on two separate loops. Also, where is all the charging circuitry? The bridge rectifier, voltage regulator, and smoothing capacitors involved in converting the alternating current that the dynamo would produce into a fixed voltage direct current for the batteries. Additionally, even ignoring those facts: let’s say after reading this paragraph someone still isn’t convinced of my claim that the dynamo does in fact not charge the batteries; then why does this torch ship with disposable (non-rechargeable) alkaline AG10 coin batteries then? It’s because this claim is provably false.

Now onto the next false claim. This was the one that I took notice of initially, and actually inspired this rant. The claim of these torches not having a battery to begin with. The disproving evidence of this claim in some cases is in the bloody product description itself. I have even seen adverts that claim that it doesn’t have batteries, to then make the contradictory claim of a 15 minute running time at full charge.

Closing thoughts

I honestly never intended to talk this much about this budget torch. However the more I looked into the item the more I found to say. To sum it up for you: everything from the build quality, to the false claims: make this thing is absolute dreck.

I think the main reason as to why these types of products can make outlandish claims and still sell is because of their price. They are so inexpensive, that returning them may cost more in unreimbursed postage costs, than the refunded price of the product. For example: a torch costing approximately £2.50, will cost £3.10 (at time of writing) to return via a Royal Mail UK only “small parcel”. This is of course assuming that the customer bought the product from a UK distributor.

If it was bought from China, then a return is basically not financially viable. The international postage is only cheap one way; and that’s due to bulk export shipping from China. Consequently, I have had experiences with seller’s who have contacted me offering a full refund with no return if I removed a (well deserved) negative review I have given for the product. That’s likely the main reason why they have such high reviews (4/5 star average on amazon); because they buy off the negative ones; like mine.

As for my final word on the torches themselves: I think that they are basically designed to be factory fresh e-waste. They will go from the factory, to the seller, to the customer, and to the bin faster than should be acceptable. This due to their own shoddy nature and little else. They are a good testament to the saying: “you get what you pay for”. One could also use the saying “buy cheap, buy twice”, that is if a person actually intended to use these torches for their advertised use-cases. Good luck camping with this piece of hot shit in your back pocket.

Thank you for reading.

#0010: Device analysis of a USB resistive load

Otto

#0010: Device analysis of a USB resistive load

Preamble

This will (hopefully) be a start to a series where I take a look into various devices and analyse them. My intention is to begin with very simple devices and steadily ramp up to more complicated ones as time goes on. The idea is to give the reader enough information about the device (design, function, components, etc) to the point that they can conceivably create their own. As well as in some cases recommending certain modifications, tools, adapters, or companion devices for optimal practical use.

Device information

This is a resistive load with a male USB plug interface. It’s intended function is for testing the current output of USB power-supplies and power banks. It has 2 current draw settings, these include: a 1 ampere and a 2 ampere mode. This device is operated using a two state slide-toggle switch, which allows alternating between the two current draw modes. Additionally it uses a common anode bi-colour LED as an indicator for these modes. Green for the 1 amp and red for the 2 amp mode.

The general layout and configuration of the 5 ohm wire-wound power resistors is what makes this device function. One resistor (R1) is always in circuit, in both the 1A and 2A mode. Within the 2A mode, R2 is added (in parallel to R1) to the circuit. Adding R2 in parallel to R1 reduces the circuit resistance to 2.5 ohms, which in turn draws 2 amps from the power supply.

1A mode: R1 in circuit (5V/5R=1A)
2A mode: R1 and R2 in parallel (5V/2.5R=2A)

Schematic

made using https://www.digikey.com/schemeit/
common anode bi-colour LED

Key

R1: 5 ohm wire-wound power resistor
R2: 5 ohm wire-wound power resistor
R3: 560 ohm resistor
L1: light emitting diode (green)
L2: light emitting diode (red)
S1: toggle slide switch

Recommended modifications

  • 3-state switch or additional switch (for device OFF state)
  • Heatsink / fan (to efficiently dissipate generated heat)
  • PTC resistor (as a safety temperature cut off)
  • male USB to female USB extension cable (for allowing easier multimeter access)

Additional switch

Due to both states of the USB resistive load’s two-state slide-toggle switch being used during the operation of the device, the device has no plugged-in OFF state. This means that it should not be left unsupervised whilst plugged into a power-supply as it would be active at either switch state. Either adding an additional two-state switch or replacing the current one with a three state-switch, will allow the device to have an OFF state. Whether or not this is considered valuable, is largely subjective. However personally, I like the option of turning a load off without necessarily having to unplug it.

Heatsink and fan

The reason why leaving this resistive load active and unsupervised is a concern; is predominantly due to the functioning of the two large 5 ohm power resistors. These resistors dissipate around 5 watts each (5V*1A=5W) and generate considerable heat as a result. Because of this, I recommend the addition of an appropriate heatsink to be attached to these resistors in order to dissipate this resultant heat. As it is now, during continuous operation the resistors heat up to the point that they can not be handled with a naked hand. This level of heat could pose a possible burn risk, or fire hazard.

The addition of a heatsink will allow the device to run continuously without reaching these same high temperatures, it does this by dissipating the heat generated within the resistors in a more effective manner. I.e. moving it into the environment quicker, so that it doesn’t concentrate within the device. An addition of a mounted 5 volt mini fan will enable the cooler ambient air to run through the fins of the heatsink and further improve it’s ability to move heat out of the device. I specify a 5 volts fan because it can be powered from the device itself.

In addition to allowing the device to be handled after extended periods of operation, a good heatsink will in all likelihood also extend the lifespan of the two 5 ohm power resistors. It does this by dissipating any generated heat before it reaches levels that may damage either the components themselves or their neighbours. Generally speaking: devices that run cooler, live for longer.

PTC thermistor

As an alternative to the above two fairly common sense modifications; one could also choose to incorporate a Positive Temperature Coefficient (PTC) thermistor as some kind of safety shut off in the cases where the device reaches any critically high temperatures during operation; essentially as a reusable temperature fuse. The reason why I am dubious in recommending this is that: although it will make the device safer to use in a continuous application; attaching a PTC thermistor in series with the two power resistors may actually affect the resistive load’s performance if not it’s ability to function entirely. I am not sure as I am inexperienced with the application of thermistors in general, and have yet to try this particular use-case out.

My working theory is that since a PTC thermistor increases resistance as it heats up, and with this device’s current draws; it will quickly lead to a positive feedback loop where it’s resistance generates heat, which will generate more resistance, and so on until no current can pass through it – essentially becoming open circuit. I believe that the heat generated from the low resistance power resistors will kick start that sequence; and that the increasing circuit resistance from the PTC thermistor will quickly negate the the power resistors’ ability to draw current. Even if the thermistor’s resistance doesn’t increase to the point of open circuit. It only needs to be consistently higher than the power resistors’ 5 ohms in order to hamper device functionality.

Still, perhaps there is a configuration where the PTC resistor will not negatively affect the power resistors, while still being functional as a thermal fuse. Perhaps if the trip temperature of the thermistor was high enough, or it had a position on the device where it only heated up in cases of catastrophic environmental temperatures. Basically a setup that allowed for the added safety of having a thermistor in circuit without it negatively affecting the functionality of the device.

USB extension cable

I decided to create my own USB extension cable rather than use a prebuilt one. The main reason for this is that I fear that a random off the shelf unit my not be designed to handle current draws of 2 amperes (even if it’s vendor says that it is). This would mean that the cable itself would provide a level of resistance that would become a limiter to the amount of current that the resistive load can draw.

Generally if a USB cable is offering resistance, it will be in it’s cable and not in it’s plug and socket. Either the cable itself is too thin of a gauge, made of inferior materials (aluminium instead of copper), or is long enough to cause voltage drops at higher currents. With this in mind, I used thick gauge copper power cables (taken from an extension cord), and a salvaged USB plug and socket. I also made sure to keep the total length of the cable short; just being long enough to allow comfortable use of a clamp style multimeter.

Which actually brings me to the purpose of this little extension. The pictured USB extension cable is designed to allow the use of a clamp multimeter (one that can measure DC current). Alternatively, if I didn’t have a clamp multimeter, I would cut the 5 volt line in half and terminate it’s two ends with banana plugs. That way I can insert a regular multimeter in series within the circuit; and measure the actual current draws.

As an alternative to using a DIY USB extension and a multimeter, one could just buy a USB voltmeter/ammeter. Such as the one pictured. Although these things, in my opinion can skew the results: due to them (in my experience) imparting some level of resistance on the circuit; they are certainly more convenient to use. Which one a person prioritises: accuracy, or speed (neatness, etc.) will largely depend on their preferences and use-cases.

Closing statements

Although the build quality of this device is more than acceptable (i.e. it doesn’t feel like a shoddy product), it is clearly built to a price point. Only having near enough the absolute necessary components to function. I believe this to be the case, not just because of the miniscule bill of materials (BOM), or the use of inexpensive components in that list. But rather because of the in my opinion necessary things that were left out; namely a basic heatsink.

Although it actually functions fine as is; at least for short operations. If you wish to use this device safely continuously for longer periods of time than a couple of minutes, modifications will need to be made.

Sources, references, further reading

https://en.wikipedia.org/wiki/Thermistor#PTC

https://sciencing.com/difference-between-resistive-inductive-loads-12181159.html