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.
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.
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.
Found that the resistance of this potentiometer doesn’t change when it’s moved
Are sure you’re measuring across the correct terminals? The resistance between the two terminals of the resistive portion is constant. I would expect the resistance of a failed pot to either be zero or infinite
There’s a test pad on the PCB labeled “LT” (left trigger). I used that and compared it’s resistance to ground to that of the right trigger’s test pad. I got about 6-10k ohms on the working one (right trigger), and 3.9-4.4 on this one.
This one should have you covered. They’re quite nifty. Can do a lot more than what you ask.
USB C Tester,KJ-KayJI 2 in 1 Tester Color Screen IPS Digital Multimeter(2022),Voltage,Cur,Pwr,Resistance,Elec,Temp,Capacity,Tme,Fast Charging,with USB Clip Cable Support PD2.0/PD3.0,QC2.0/QC3.0,BC1.2 a.co/d/6RlmtOo
There are simple testers like this. It’s rather overpriced for what it is, but it would be trivial to make one yourself. That will only do a continuity check though. If you want to know what the current or speed ratings are, you will need to read the chip in the cable.
Don’t charge LFP to 4.2 volt! The crude “check voltage and if below 3.6 V keep charging” is okay too as long as the maximum current is within battery spec. But measure while charging, don’t turn that off to measure the open circuit voltage.
An international parts order is too complex for such a small thing. I’m not in the USA or China. So no TP5000 for me, got to work with what I have.
I agree, no charging at 4.2 volts. The current charger I built seems to work well enough. I ran some tests and it charges within spec. The reason I turn off the charger to measure cell voltage is because otherwise I’ll mainly be measuring SMPS noise.
Anyway it beats the charger available in the local market, which is clearly unsafe, no matter how much they assure me that it’s ‘totally OK’.
Word came down from on high, that I wasn’t to use 60/40 for teaching anymore. Usually went through about 1kg annually, and I had just stocked up. I think I had just gotten 8kg, or something like that, because of the bulk rebate, about a year before. And what was I to do? We weren’t allowed to have the solder on premises anymore.
So anyway, 60/40 for 1.0 and 0.7mm and some sn/pb/ag for 0.25mm. And no, I don’t have ventilation for my workspace, but I do have enough solder to last a couple of lifetimes.
The navy gave me a spool like 5+ years ago. It has no label. They were going to trash it. I have no idea whatsoever what its composition is. It’s rosin core and that’s about all I know. I also have a few different gauges of safety wire and shear wire.
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.
As long as it fully saturates i thiink it’s fine, i’ve personally only had issues with too slow switching when i switch the mosfet many times a second, or when i didn’t give a high enough voltage to fully saturate it, both of which usually led to a smoky mosfet
Just based on my experience and knowledge of these batteries, which is not that much really, don’t take any of this as gospel.
Constant voltage current-limited power supply is probably the easiest way to charge it, a regulator + current limited supply like you mention would be one way of achieving that, will waste a lot of the power and charging speed will be limited by how much heat the regulator is able to dump (which for a typical TO-220 regulator without heatsink is like a watt or two? So you’d have a max charge current of like 0.5-1.0 amp)
Your current approach probably also works just fine, but i’m not sure how good it is for the batteries in the long run
You can find charger for sale online though, at least modules that you can solder up to a battery holder or whatever, i would go for one of those if you plan to use these batteries for a longer period of time
I’d order online if there was a LiFePO4 charger on the market. However, in my country I’ve been unable to find one, and importing (excise & duties, paperwork) is more work than building it myself. I’ll also likely need a design that I can cheaply include on custom PCBs for manufacture (not for sale to end-users, but for internal use by maintenance technicians).
I gave it a test on a cell today and it seems to charge fine and at a reasonable rate – but in a sudden flash of brilliance, I forgot to physically connect the ADC pin to the battery, so it couldn’t shut off. Well, that’s what testing is for I guess.
Anyway after fixing this, it looks like I can call this a win and move on. If it undergoes destructive optimization, I’ll report back here with a warning to others.
There are really charging curves that should be followed to avoid damaging the cells.
You want to charge up to a certain voltage at a current (related to the battery capacity I believe) and when the cutoff voltage is hit, you switch to constant voltage (the max voltage of the cell) and then slowly drop the amperage as the battery is topped off.
I’m not sure about your cells, but some LiFe are 95-98% full at 3.45-3.5 volts, but the problem is that the voltage curve is really flat from 40-50% charged up to 95%. So you need really accurate measurement if you want to charge to 95%. The last 3-5% is when the battery ramps up to 3.65v and really is the riskiest part of the charge. It’s also the highest wear part of the battery use, if you can avoid charging it all the way up to that your cells will last much longer.
My normal lithium battery charger automatically slows its charging speed as battery voltage nears its capacity. I could set it at 1000mah and it will step down to less than 1/10 of that before charging is complete.
It’s just that it’s really tricky to charge the final bit because the middle 80% is such a flat voltage curve. They have a 1000x life when they’re taken care of.
It’s tricky to stop at the right point, because lithium iron only have a very small voltage increase between like 40% and 90% and they ramp up to full voltage right near the limit of their capacity.
What you are talking about is nothing special at all and not following a charging curve. The curve automatically looks the way it does when charging CCCV. Constant Current -> Constant Voltage.
askelectronics
Active
This magazine is from a federated server and may be incomplete. Browse more on the original instance.