Is certainly in the realm of feasibility, at least in a technological level. You can get flexible e-ink displays that are less than a mm in thickness. Typically the hardware that changes the display is the bottleneck on size.
That being said, I have doubts about the idea of “manufacturing for cheap” as even small e-ink displays can cost $20+.
I did find some 1mm price tags on Alibaba for 3-5$ which could possibly be repurposed. The issue is I really would like to get the price driven down to $2-1, maybe even less… I want this thing to be able to mimic any kind of card game, and some of them have up to 300 cards… I think the plan would be to have 150 card sets. That would cover a lot of games, and if your playing a really nerdy game that does need 250+ cards or something there is a chance your friend might also have a set.
If you could get the price tag $300 or less you could probably get a lot of hard-core tabletop card gamers. I know thats a huge price tag, but the product isn’t meant for the masses.
From looking at the LED bulb, I can tell you that it will not work very well in that flashlight.
The reflector of the flashlight is built so light coming from a very small source (like the filament of an incandescent bulb) is directed forward in a focused beam. With the led bulb, light is coming from 10 different spots, none of them being in the focus point of the reflector. The result will be a spread out beam that won’t be bright over longer distances.
The only type of LED bulb that could work is something like this car replacement bulb that keeps the light source to a relatively small spot. But I don’t think those are available in the size you need.
Not really. With that bulb, all the light is focused forward, not to the side. The light will never hit the reflector, it is only focused by the lens in the LED housing, and that isn’t enough.
The reflector of the flashlight is built so light coming from a very small source (like the filament of an incandescent bulb) is directed forward in a focused beam.
I agree, but I also think that using a modern LED with a single source of forward-facing light is fine. However the emitter would need to be properly positioned in the light.
Here’s a very similar host (from one of the best low-cost flashlight makers) showing a properly aligned LED and reflector:
Thanks- I got the thing running through a breadboard power adapter of all things, to confirm the pump was still living, so I will try what you linked! I am beginning to wonder if I wired my last adapters’ poles. So, this might have been user error on my part, doh!
Could you do similar to diagram 2, but instead of an N-FET use a P-FET between the battery and first resistor in the potential divider?
Add a gate pull up resistor to source to ensure the FET is off by default, have the micro pull the gate down to take a measurement. You’ll probably need to add another resistor on the control pin to 0V to limit the voltage there also, but those two can be much much higher values to really limit current. Or use a zener/TVS diode instead of second resistor to clamp the voltage instead of dividing (more robust).
Switch it with an NFET
The micro will see 0V or divided/clamped battery voltage on the measurement pin.
Not sure I understand this point. Which resistor would you replace with a diode?
Sorry, I think I was talking nonesense (doing this in my head and just woke up 😅).
Not sure it’ll work with just a P-FET actually. You’ll likely need to control the PFET with a NFET, otherwise you still end up with too high a voltage on your control pin when the FET is off due to the gate pullup (unless you can use a fet with a very high Vgs Threshold and then drive it push/pull from the micro, but this isn’t really best practice).
The above comment about diodes was to protect the microcontroller pin, but you end up not being able to control the FET doing it that way.
I think either your existing Option 3 or PFET upstream of the divider, switched via an N-FET is the way to go.
Is this not the same ESP32 with an antenna? Although I don’t know how the nRF52840 from your question comes into play here. Don’t you normally use an ESP or an NRF, and not both at the same place (with the exception of a gateway maybe)?
The nRF was a useless inclusion tbh, sorry for the confusion. The nRF already has an smd antenna.
The thing with those antennas is the size of the antenna vs the size of the module, it’s almost twice the size, negating any benefit of having such a small module.
Hence my desire to use an SMD antenna on a small board instead.
So you have these boards already? Or could you just get other boards with an ESP32 and LiPo charger? Because many already have a printed or ceramic antenna built-in.
Do you know of others with charge controllers with that from factor? The only one close to it I’ve found is the is the m5stack m5stamp, but it doesn’t have a charge controller.
I don’t mind creating the daughter board, I think it could be fun.
Something weird happened... So I edited my comment: Ive used those exact relays, 3 in a single prototype that I was tinkering with quite a lot, so what worked best for me in the end was mounting a DIN rail into my enclosure (Any box would probably work for you? I needed IP65 so I used a proper box with glands for incoming wires.) And then the relay boards were hot glued to DIN rail mounts... (The relay boards are then lined perpendicular to the DIN rail) That ensured that I could add or remove the rails as needed.
The rest of my circuit is also mounted on another DIN rail... Also allowing me to swap out main boards as I programmed/ upgraded them with minimal effort.
This was all connected by DIY 'ribbon cable' so that plugging and unplugging was also a breeze..
Granted this all might be overkill for you? Ive also have had projects that still live in shoeboxes and they work but obviously it all depends on your use cases?
Just remember, if you go the box route, to make your life easier, make sure the box is big enough to work in if anything is to be mounted permanently. Its a massive headache trying to feed one wire past all the others into the hole if you are working 20mm from the edge of your box.
Hope this helps!
(Second edit):
I read like my arse... If youre installing inside the switchboard and already have din rails, then a rail mount would be the most convienient solution
I sort of hate relays. For 12VDC and a light load, I might consider a depletion-mode MOSFET and a diode to protect the battery. Much faster switching time than a relay, and quite probably lower internal resistance! Also no moving parts and much lower current consumption. There are some cases where it’s not appropriate though.
Anyway, I looked through the datasheet and you’re right – no mention of wear and tear from just leaving the solenoid energized, only from switching. Failure time also seems to increase when switching high currents. Since you don’t seem to be doing either of those things, I think you should be in the clear.
I was thinking about that, but if they are using 12VDC + light load a MOSFET would be more cost and space efficient, and probably more electrically efficient too. No real voltage drop, and just a few milliohms added to the load.
I mainly use SSRs to switch mains power, although it’s true they can be used for other things too.
The two through hole pads by C19/20 arent soldered and the one above it looks to be a bad joint
jumpers on the right arent connected in the same spot
extra traces by the IC
components can die, especially ICs and capacitors from ESD and drops respectively
PCBs themselves can sometimes just be faulty from the factory and have damaged traces.
Another thing is that small ICs like that tend to be fairly difficult to stick down all the pads. Reworking that might be a good option if checking the above doesnt work
Thank you, I will reflow C4 and add C16, but C10 and C14 look fine from the sides.
The messy/missing joints near C17, C19, and C20 are optional components for the other side. (Unused surface mount USB port with through-hole mounting pins and an unused jumper.) Right-hand jumpers are all optional and unused from an earlier prototyping stage.
What do you mean by extra traces by the IC? And you’re absolutely right about the small IC. It’s the MAX17640, and at 2mm x 2mm it’s a piece of work to land correctly.
I was referring to it more as a difference which might be the source of the issue. For example, one via is fairly close to the pad for C16 which could be shorted (probably isn’t, but still a good idea to check). It could be a wiring issue but could also be a board manufacture issue.
On a KISS basis - I tend to just use a bimetallic switch or omit the temperature control and just run the fan from power up. It’s possible for a processor to suffer some non-handled exception where it no longer executes the temperature management routine.
This was a few months ago so I can’t recall a lot of the specifics unfortunately.
What I can recall was using a 90w Ali Express soldering iron with a conical tip to solder a damaged original Xbox controller cable. The leaded solder seemed slow to melt on the tip but wouldn’t melt to the wire when I applied heat on the under side.
Sorry I can’t tell you more. I was looking to do some practice this weekend and wanted to know if I should be ordering a thicker tip or something.
The temperature is set too low. The solder should melt almost instantly when applied to the tip if the iron is set to 350°C.
Those fine point conical tips that typically come with soldering irons are terrible. Get a 2-3mm chisel tip, that will be suitable for most soldering jobs.
Wattage does not mean how hot it gets, it means how fast it gets to the desired temperature. Also Chinese vendors tend to exaggerate greatly with specifications, especially with cheap products.
My local children museum has something like this. Let me see if I can find a picture to give you an idea of the set up. It does look like it would be $$$ for set up. What’s your price point?
Cool! I’m still looking for a picture. I’ll post when I find it but thinking about this more I know there are a ton of toys like this made. Most are for older kids and are priced at about $20-80.
Look up circuit station kids science and you should get an idea of the kits.
My kids had Snap Circuits but it’s a bit complex for a toddler. It’s probably the most basic circuit designer I can think of though. They did a great job. If an adult is helping it would be fun for both.
Yeah around three they should be able to do it with adult supervision but it’s still a bit of a toss up on if they are going to put the small parts in their mouth. I can’t find the a good photo of the big one at my local children museum. It’s going to drive me crazy. I’ll probably just have to take a picture next time I go in.
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