Now suddenly, there are embedded Raspberry Pis and ESP32s doing realtime facial recognition and video feeds.
Oh yes, you can buy an ESP32-S2 for 2$ and run with Python or something higher level than C and get something that would’ve done with an AVR in days quickly up and running in hours. It is the brand new world of hardware is cheaper than developer time and nobody knows how to code anything and read datasheets anymore. Also there’s the trend of cloud-backed platforms like PlatformIO that essentially make it so you can’t ever develop anything completely offline and become hostage of some provider, ecosystem etc.
Something that might interest you is ESPHome and HomeAssistant. Heads you, you can now flash a microcontroller (be ir an Arduino/AVR or ESP) from a Chromium browser :).
and nobody knows how to code anything and read datasheets anymore.
You seem a bit bitter which I can relate to. As someone who cut his teeth writing assembly for an 8051, I remember feeling a bit cheesed by people using arduinos to do what could be done with a 555.
My career has gotten comfy, but I can feel my skills stagnating with all this new stuff coming out. I of course would never ship a product with a Raspberry Pi embedded in it, but I’d like to have a feel for how to solve problems using newer more advanced hardware. With that in mind, do you have any recommendations?
It’s not that you can’t make a more efficient device without it. Hell, if you wanted to impress people, you can absolutely populate a board with IC’s and traces and build your own logic.
Orrrrr you could spend $45 to get a full GPIO header backed behind a vast online electronics community. Tbh pi’s, arduinos, and other ARM core hobby kits give you a root skillset to base any project on. Once you can get logic through your code, there’e no need to figure out wire logic if you can program based on I/O and software variables. But it -is- a different skillset that you’ll need to learn to use it efficiently.
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.
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.
What do you actually need? 1 microsecond with “decent bit” is not exactly a lot of information. An oscilloscope would fit that perfectly. How do they not work how you want them to? Who told you that you need something else?
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’.
Yes, in the sense that I’d expect it to use less power than in incandescent when lit and no more than a few watts when “off,” but I figure any kind of LED I could put in it and any sort of controller short of shoving in a full-blown Raspberry Pi 5 would be able to manage that.
Replacing the linear elements with switchers means more noise in the power lines. How much more, and whether it’s noticeable or tolerable will be down to you.
The linear regulators are still there. It’s the rectifier that gets replaced. I guess the main difference in the power side is the high frequency noise of the switching PSUs vs the low frequency ripple of the rectifier, I’m not 100% sure if 7x12s are immune to them at least at audio frequencies.
MELF stands for Metal Electrode Leadless Face although anyone who has had the pleasure of working with them will tell you it stands for Most End up Lying on the Floor.
It’s great to see you exploring different platforms for your electronics inquiries! Regarding your setup with the variable boost converter, 18650 batteries, and the 12V LED strip, your analysis is on the right track.
The boost converter indeed stabilizes the output at 12V irrespective of the input voltage. In your scenarios, both setups - series and parallel configurations of the 18650 batteries - should effectively power the LEDs at 12V through the boost converter.
Your assumption about the parallel circuit draining faster than the series circuit due to the boost converter’s behavior is accurate. Since the parallel circuit offers half the voltage but doubles the current capacity, it will indeed discharge quicker compared to the series circuit.
Concerning the choice between parallel and series setups, there are trade-offs. The series circuit might experience fewer losses through the boost circuit due to its higher efficiency with higher input voltages, potentially reducing heating issues. However, as you mentioned, charging cells in series isn’t feasible with your TP4056 board, limiting your option to the parallel configuration.
Given your charging constraints, sticking to the parallel configuration seems more practical for recharging purposes. While it may drain faster, using the parallel setup is compatible with your charging board and allows for easier recharging.
I noticed your edit about the TP4056 board being compatible only with parallel charging, which aligns with your previous discovery. It’s a crucial factor to consider in maintaining the functionality and longevity of your battery setup.
If you want more insights on the efficiency differences or additional alternatives for charging in series, I have an informative post on converter types that delves into various setups and charging considerations, which might offer further clarification for your project.
Feel free to explore and let me know if there’s anything specific you’d like to dive deeper into!
On the topic of lithium polymer charging, it has this to say:
Charge and discharge characteristics of Li-polymer are identical to other Li-ion systems and do not require a dedicated charger. Safety issues are also similar in that protection circuits are needed. Gas buildup during charge can cause some prismatic and pouch cells to swell, and equipment manufacturers must make allowances for expansion. Li-polymer in a foil package may be less durable than Li-ion in the cylindrical package.
However this is not a lithium polymer battery, and as it’s a 32700, it is not a prismatic or pouch cell either. It is a lithium iron phosphate (LiFePO4) cylindrical battery in metal housing. Battery University does have them listed in their table of chemistries (in case you’re curious), but they don’t seem to have much detailed information. Enough to build a charger though :)
Anyway, thanks for your reference in any case! I’m not responding to criticize you, only to improve the utility of this conversation in case someone else finds it on search :)
Your 2nd best bet would be to get the pin spacing, and filter your search using that.
Your first best bet would be to just replace both ends.
I settled on a ‘standard’ and just bought a massive kit of each of those connector types- wire-wire, wire-board, wire-panel in M and F, in various pole counts. Buy once, cry once.
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