It’s similar to AC-DC. From a simplistic perspective, efficiency at idle will be 0% because the converter itself still uses some power, then efficiency increases with load since the converter overhead becomes less significant as the useful work increases. Googling “dc dc converter efficiency curve” gives plenty of results.
They might be willing to spec it as "quiescent current" (current drawn at 0 load) even if they don't provide a full curve. Annoying that it's not on the datasheet.
If you mean a replacement slide-in US standard module - I fear that your chances are slim. I don’t know of a standard that applies to such plates. As it came with a, presumably, external disc drive - asking that manufacturer or its US agent/distributor for help might get something. Even a free replacement power supply. Worth asking, surely?
I don’t recommend using an inline adapter - unless used vertically, the leverage would be too great, unless you added a third leg… You might look for a right angle adapter - that’s the norm in the UK. They can work out well.
Otherwise, you could get an EU socket strip, replacing the plug on the end of its cable with a US one (if it doesn’t actually come with a US plug already).
Mostly I just work in a well ventilated area. Oh and for sure disconnect power before desoldering anything.
Other than that, I avoid taking apart microwaves (beryllium, high voltage), anything with a CRT (imploding glass, high voltage), and high voltage transformers (transformer oil, high voltage). Also any medical equipment (chemical hazard, radiation hazards, biohazard, high voltage, imploding glass). Oh and no unexploded munitions for reasons that should be obvious (people still salvage these in my country and it sometimes doesn't end well).
I find a hot air rework station+tweezers a much faster way to salvage than jamming a hot iron into boards. Also lets you salvage SMT components, which are most of the better parts these days. For 1970s stuff, it's mostly through-hole, I'd test the parts before trying to reuse them. Capacitors especially. Got to love those big transistors from our side of the Iron Curtain though.
Your GPU might be having problems, but the other problems you list sound like either a bad hard drive or a virus / bad windows install.
There are several utility programs you can download that will check your hard drive for failures. I would back up any important files and then run those. If the hard drive is bad, replace it. Either way you will probably want to re-install windows from scratch.
It really depends how much power/current you are switching. If you are switching 1A with a beefy heatsink FET, the time spent in the linear region is short enough it shouldn’t be a problem. If you are switching 50A though it then you might have a problem. Depending on how that gate divider is set up, you could still potentially damage the gate of the FET when shorting it to ground to discharge it if I understand how its hooked up correctly.
Ideally you would use some kind of FET driver with a voltage source (e.g. linear regulator) to turn on and off the gate plus the gate resistor.
It has 3 pins, and I found that it’s a linear (B), 10k ohm (130, as you said), potentiometer. I found similar ones, but the 9 and 5 at the top concern me. The others that I found have a 60 and a 6 there instead.
Potentiometers are pretty basic things. About the only thing I can think of that would be specified electrically is value (10k), wattage rating (but I doubt much current is sent through these in this application), linear/logarithmic taper, tolerance (often 5%, or 10%) and maybe the type of contact/track or something (probably doesn’t matter).
Those numbers could be manufactured date or lot codes or similar.
How does the thumb “wheel” attach? Or is it built in? I can’t tell from the single pic.
Other things to consider are the pin spacing and physical dimensions.
Im sorry, noob here. I don’t know what the voltage at the reset pin would be when the capacitor is discharged, my first guess would be 0v but the answers there say it’s the reverse - VCC at power on, then goes to gnd as it charges.
If that’s the case, I think it’s exactly what I need.
I’ll test it out later today (and I’ll go read more about how this capacitor+resistance circuit works…).
As you said before power on capacitor is discharged. Right after power on capacitor is still discharged, so voltage on capacitor is zero, so reset pin has Vcc. With time capacitor gets charges and voltage across capacitor increases and reset voltage becomes closer and closer to ground, until it is ground. But it is important to consider what happens at power down too. At power down capacitor is charged. If power source becomes high impedance at power down, then reset pin will probably go down to zero in time but may take a bit time depending on what source exactly does. But if power source is connected to zero at power down reset pin will observe minus vcc and slowly go up to 0. If reset pin is sensitive it may be a good idea to protect it with a diode.
I’m not entirely clear on the problem, but yes - the circuit as drawn makes the microcontroller pin start high, then fall after some time. Do you need the microcontroller pin to have a different voltage than the transistor base (I assume when you said gate you mean base…gates are for FETs), or is this good enough?
I still couldn’t come up with a way to make it work using a resistor-capacitor circuit, but I did learn a lot (that particular rabbit hole led to me an article discussing capacitance in potato tubers…!).
There is probably a better way of solving it, but at least I got it working with another transistor to “decouple” that sensitive pin from the base. I’m not exactly sure why there’s a negative voltage across base and emitter, but it was preventing boot.
I’d be very interested in hearing any criticism you would be willing to share. I have hopes of moving this from my breadboard and solder it to a PCB so I can put it into a paper-cut lightbox that will be controllable from HomeAssistant, but I wouldn’t want to risk setting anything on fire…
One thing that concerns me is that 7333A. I only have it in a TO-92 package, and while it’s only powering the ESP-01S, which doesn’t really draw that much current, it still gets uncomfortably hot to touch (I can hold it for a few seconds, but not much longer). Is there a better alternative, or is it supposed to get hot?
Thank you!
[edit: updated the circuit, I had misplace a resistor]
The 7333A is a linear regulator, which means it drops voltage by converting power to heat. Typically those make sense when the input voltage is close to the output voltage or the load is very small. If it’s getting too hot, the load is high enough that the efficiency will be very bad…whether or not this is a problem depends on your application.
Some random site claims 170mA and another claims up to 400mA. 170mA * 8.7V (12V in minus 3.3V out) = about 1.5 watts, which is too much for a TO-92 package.
Can you use a tiny buck converter instead? Or a larger package for the linear regulator that can add a small heat sink?
As for your actual circuit, the second transistor is an interesting idea (you’re using it to invert the state so you can have the GPIO pulled in the non-problematic direction?) and I don’t have enough experience to give further suggestions.
The strips use 3V white LEDs, power to which is delivered via resistors or linear current regulators. Unless you see any inductors, there is no buck converter from 5 V to 3 V.
Why does this matter? Well, with resistors and linear regulators, 𝐼in (current in) pretty much equals 𝐼out (current out). So the efficiency 𝜂 = 𝑃in / 𝑃out = (𝐼 × 3 V) / (𝐼 × 5 V) = 60 %. Extra cable resistance will reduce the current, brightness and power, but still exactly 40% of power leaving the USB charger will be wasted before it gets to the LEDs.
However, I would advise against multiple, cheap USB connectors in the circuit: when moving the setup, their resistance changes somewhat and you would get blinking. The worst thing that could happen is a switch, such low voltage cannot spark over an oxide layer and eventually even small movement will blink the lights. I would get a good thick USB cable and solder it directly to one of the strips instead of whatever it came with, connecting the other with some thick wires.
So it does not matter, if you want better efficiency, use 12V (75%) or 24V strips (87%), or get just an LED array without resistors that needs a constant current driver (theoretically 100% but CC PSUs are slightly less efficient). Or make a constant current driver by fine-tuning the voltage of a PSU (by adjusting the feedback resistive divider) to 0.5-1 V above the LEDs’ voltage drop, then using an appropriate resistor to limit the current.
Just in case you really didn’t understand: it’s wave, not vawe. It’s a common spelling mistake, especially for people whose native language doesn’t have the w letter.
Not too sure about the vacuum effects, I suspect the electrolytics wouldn’t last long as they are built to handle a certain pressure then pop to vent in a controlled manner in the event of failure. The positive pressure under operation is also likely to inject liquid refrigerant into the components and into layers of the PCB and such, that cant be good for any of it, that would definitely kill capacitors by displacing and or dissolving the electrolyte fluid.
As for the longer term, I know that pretty much all of the phase change fluids you would likely use act as pretty strong solvents in their liquid states, so I doubt the hardware would survive terribly long.
There are immersion cooled computer systems using an inert liquid like Perfluoro(2-methyl-3-pentanone) but that is a different process to phase change refrigeration.
Caps are definitely the first thing to try. To add on, the higher your frequency, the smaller caps you’ll need. At 10kHz you’ll need around 200uF of decoupling but at 50kHz you’d only need around 40uF. The smaller capacitance means you can find caps with better ESR, or just fit into a smaller space in general.
The drawback of higher frequency is that you’ll be charging and discharging the gate of the MOSFET more often, which could mean heating it up and hitting thermal limits quicker. There’s also a tradeoff within the MOSFET itself between low on-resistance and lower required gate charge - for slow switching you can find a FET with low Rds and high gate charge since youd be switching less often, but for very high frequency applications the amount of energy you put into charging and discharging the FET (mostly since the FET will spend a longer time in its linear region) can outweigh the savings of the lower resistance. Yay tradeoffs!
Thanks for typing this up! This helps me understand a lot more about what is going on.
I may have purchased too large of cap for the first try: 470uF. I bought it online so still waiting for arrival. I’ll get some in the 40uF to 200uF range for more testing
470uf should be fine - bigger is almost always better, except if you sacrifice higher ESR for it in an application that requires lower ESR. It’s pretty common to combine a large cap with higher ESR (like an Electrolytic or tantalum) with low ESR ceramic caps. That way the large cap can handle the high speed bulk C while the smaller cap can handle the high speed stuff and switching edges.
Did you make sure the cap you picked out was rated for the voltage you are working with? For hobbyist stuff it’s usually a good idea to heavily derate voltages, to avoid blowing things up. For example, if I was working with a 24V power supply, I wouldn’t nab a 25V cap; I would spring for a 35V (or even a 50V if I’m feeling particularly paranoid). You’ll see derating like this commonly in commercial applications, and extremely frequently in military/aerospace applications.
As a rule of thumb you should always derate by at least 20%, then increase to 100% depending on how much ripple or switching the cap will see. For this application I’d probably want to derate to at least 50%
Is the capacitor an x2 cap for voltage surges? Looks like it. The rest is just normal stuff. Not my field, been out of school for years and am an idiot. That being said I’m curious: what’s the inductor by the Emi suppression capacitor for in this circuit? Is it just to form a tank circuit to heat the kettle more efficiently?
idk, not familiar with those things. the kettle can has 5 modes of temperatures: 60–100 °C. Its really nice, just insanely loud. More pictures if case it gives more info, sorry for the bad quality, hope its readable
Top is a relay, bottom is a capacitor. Thanks! The sound you’re hearing is probably from a piezo buzzer like some one else mentioned. I wish I was home so I could send you a picture of one. They can be really loud!
I haven’t got enough time on my hands right now to review the whole desingn, but one thing that jumps to mind is that you’ll want to use an antiparallel diode on each relay coil to suppress the negative voltage spikes when switching it off.
Be sure to keep adequate distance between high and low voltage traces. The ground plane seems awfully close to the N trace.
Other than that, I’d happily welcome more PCB and/or personal project discussions!
What did you hook up? You mentioned using cords? But first off, what you pictured, you need to make sure it’s wired correctly. There is no standard for barrel jacks. The center pin can be positive or negative and the jacket and be positive or negative. If you’re using a generic 5.5x2.1mm female barrel jack most generic 12v power supplies overwhelmingly do center pin positive and jacket negative. Once you get polarity correct check the amperage rating of the supply and the motor. Motors usually require huge in rush current to start and can easily trigger a short circuit protection on the supply output
Well, you could say that there are three branches of electronics: analog, digital, and discrete (sort of between the previous two). For your goals, you mainly need to learn about digital systems.
What you’ll mainly be dealing with in terms of digital systems are microcontrollers and other embedded systems. I’d say the main two places to get started with those are the Arduino and Raspberry Pi ecosystems. The first is “more pure microcontroller” and the second is “more advanced embedded systems”.
Microcontrollers are mostly programmed in C++ these days (with a few strange people like me using Assembly), and the Arduino ecosystem sort of teaches that. Microcontrollers are usually the most efficient system to make the control electronics for something like a keyboard. Sparkfun and Adafruit are good companies to buy parts to get started from.
Embedded systems like the Raspberry Pi stuff can often run a whole operating system. This is too expensive (power, space, and $) for most keyboard builds, but you may want to learn how to use them for other projects. However, they also make a microcontroller (the Pi Pico) which would be OK and can be programmed in Python.
For advanced computer peripherals, you might need to learn FPGAs. However, that can be a difficult topic to get into by comparison. So maybe leave that for later.
A good way to get started is to buy the parts for, and build, a few Arduino projects. There are specific libraries for making Arduinos emulate a PC keyboard too.
In terms of tools, at first you will just need a breadboard, some resistors, LEDs and jumper wires. Maybe a battery or USB power supply. A multimeter too.
Soon after you will probably want to learn to solder to start making your own standalone devices. You should get a soldering station with temperature control – some people swear by Hakko, myself I have a cheap-but-good Yihua soldering + hot air rework station.
Next, while Sparkfun and Adafruit are great businesses, they are not cost-effective ways to source a lot of parts. You’ll want to learn how to use the part search and ordering functions on Digikey, Mouser, Arrow, and RS Components. Maybe also McMaster-Carr if you do mechanical stuff.
When you have some working designs done, you will probably want to learn KiCAD. It’s software for designing circuits, and laying out printed circuit boards (PCBs) to send to a factory to be made professionally. Through the magic of globalization, this is actually pretty affordable! A typical run costs me 20-40$ for 10 units, and takes 16 business days – although I live in Asia, so it might cost a little more from the USA or Europe.
You’ll also maybe want to learn 3D modelling and printing, for designing cases (I struggle with this more than I’d like to admit). TinkerCAD is an OK place to get started, although tools like SolidWorks are certainly more advanced. You don’t need to buy a 3D printer unless you want to – you can just order your designs made online.
Anyway, the results with KiCAD + 3D printing can be really quite good and can last many years of use. They also let you share your design with others, so other people can make it!
Finally, if there’s a hackerspace / makerspace in your area, these are great communities of people you can learn from. Definitely check them out. They may have a 3D printer you can use, as well as other tools. Often they teach courses too.
One small note – getting from “hey neat this works!” to making and selling a product is (sadly) a really big step. So if you one day want to do that, build a network and ask for advice from someone who has gone through it first.
Man, that was a great read, from simple beginnings to selling your product. Thanks for the thorough explanation, I definitely don’t plan to sell anything, I was considering learning electronics as a hobby, but it’s good to know where to start if it ever comes to that.
Glad to help! I find it quite neat that with effort and time, it’s possible to learn to make quite advanced electronic systems yourself at home. Some of the stuff the more advanced hobbyists make is quite a bit better than a lot of mass-produced goods. We truly live in an age of wonders!
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