Thanks I did try before, but now I had success. I stumbled upon those little price tags stores use to digitally update prices. Those could possibly work for this.
My gate driver is fairly crude but you could probably make something a bit better with a PNP transistor and either pull it down or leave it floating, or instead use a szaiklai pair
It is an N channel FET. The concept is called “bootstrapping” since Vgs needs to be greater than Vth for the MOSFET to be on. When the FET is on the high side and you want the full 9V on the output, you use the diode to charge the capacitor, and the other side of the cap is 0V. Then, when the other side of the cap is connected to 9V, the charge on the cap can’t go anywhere so the voltage on the other side jumps to 18V. This creates a Vgs of 9V. Ideally you would have something better to drive the gate to fully turn off the FET, but I just used a quick and dirty driver where the bootstrap capacitor directly feeds the gate instead of being the input to the driver. Because if this, the Vgs doesn’t drop completely to 0
I won’t be using this for my measurement issue (the other options are much simpler, and i was aiming for less parts, not more), but I’ll do some experiments to familiarize myself with bootstrapping
ATTiny would definitely work. Ive use them for really really long timer systems with some trial and error.
You should maybe just look at a bigger battery depending on what lifetime you would expect? They are not exactly super low power(at least the ones I have used)
You could go with an DS1339 which is an RTC with two programmable time of day alarms. If you only need timing you might as well do that. But if electronics isn’t really your thing then just add a bigger battery for the attiny85, make sure to run it at it’s lowest clock speed.
I use the Attiny10 in this context. At 3.5V operation and using the Watchdog timer + deep sleep… that should cost you about 4.5 uA when the lamp is off. Then a bit more when it is on (about 40uA assuming whatever the GPIO is connected to is high impedance), as you have to enable the I/O clock (but most things and peripherals can stay off). So an average consumption of 10.4 uA, or 31 years of operation off two 1.5V cells – of course they’re not rated for this long and the actual light will consume far far more power. The point is that the current consumption of the system is absolutely dominated by the light-producing component, in other words the control system is highly efficient.
You can implement as a state machine, e.g. something vaguely like:
Set WDT to trigger an interrupt instead of the RESET vector. Then set WDT to trigger after 8s. Then on wake increment a register (you will need 2 registers, 8 bits isn’t enough). Compare these registers to constants that set the timer duration. On compare match, change the machine state.
Machine state 1: GPIO HIGH, timer duration 4h, I/O clock enabled. CPU sleep mode IDLE. Machine state 2: GPIO LOW, timer duration 20h, sleep mode POWER DOWN.
I think in assembly language but should be a similar process in C++. I’ve successfully implemented very similar (night-light timing) algorithms on this chip. I can’t give you power consumption metrics as none have ever run out of power over the past 6 months.
no, this is fine, you can find it in routers all the time (usually with printed antennas, or wire antennas)
so it seems, however remember that at microwave frequencies you might start seeing distributed elements as a part of matching circuit (patches, open or shorted transmission lines etc) every fraction of mm is critical. i don’t know what impedance gets this thing on output, but it might be very well non-real. it’s usually done so that everything is matched to 50 ohms
assuming that output is matched to 50 ohm, which is usually the case, you can use any length of coax, as long as losses don’t kick in too badly. this means you also have to make your antenna 50 ohms. i see you’re using ceramic antenna, which provides matching circuit for you, but there are other options like inverted-F antenna (3cm long) or even smaller zigzagged *inverted F antenna or halo antennas (some 2cm dia), which would require matching. tradeoff is better efficiency (less heating; one of these antennas wastes almost 40% of power) and the fact that you can make them on your own
Thank you for your detailed reply, I really appreciate it. It answers my question and raises a whole bunch more :D, I think I need to brush up on general RF and get a better understanding of how it actually works. I shall do some youtubing and reading on it. I found a really good pdf that discussed antenna design but a lot of it I didn’t understand, so I’m going to need to learn a bit more.
if you want to measure anything rf, you’ll need a vector network analyzer like nanoVNA (some $40), this will be very useful in tuning/matching antennas (and making sure you won’t get reflections that could potentially damage transmitter if you screw up badly enough)
antenna design is usually limited by one of these things: size, gain/radiation pattern, efficiency, bandwidth (fixed here, entire 2.4ghz band)
you can probably use off the shelf antennas used for drones if these are small enough for your application
soldering coax can be tricky, don’t melt center insulation. you’ll need to size microstrip line so that it’ll have impedance 50 ohms as well www.pasternack.com/t-calculator-microstrip.aspx
I ended up using spacers so that it does not come in contact with the metal box enclosure. Thanks for pointing out the mountijg holes. It was right there and I never noticed haha. I feel like an idiot.
Thank you for your suggestion. Is it really that easy to implement? So far the people I talked with irl told me otherwise, but I will look into it and judge myself whether I am up to the task.
Exactly, hard/easy depends on your background. It’s been almost 20 years since I worked with it, I’m sure there are ready made libraries or chips implementing 99% of the protocol these days.
This trick might be more useful for people who are budget constrained. In the past I’ve resorted to cutting the plastic between the headers (making them unusable), so this is a nice alternative without the need for another tool. If budget wasn’t an issue I’d likely buy a much nicer iron and an extra wide knife-style tip.
Haha, I’ve done that too. However sometimes it rips the pads off or otherwise damages the vias. So instead I cut them along the other axis (parallel to the PCB), then remove the remaining nibs.
These days I mostly use a hot air rework station though. In my city this is integrated with many soldering stations on the market, for maybe an extra 10$. I think mine is Yihua brand, it’s quite OK.
Maybe I’m looking at the wrong thing, but I don’t see melted plastic. I see a collapsed bubble (a “fisheye”) in the conformal coating that is providing moisture resistance to the components.
As a resistor, there isn’t a forward or backwards. Diodes and some capacitors perhaps, but resistors have no forward or reverse bias. Upside down might be a problem because all the electrons will fall out. /s
Did you check if your city will take them? Sometimes you need to go a specific dropoff site but usually they have instructions for household hazardous material
That’s a good advice. I checked the process for my city. I had to go to the city office, and after I provide my proof of residence they would give me a voucher. I could then use that voucher to dispose any hazardous household waste at a designated waste collection center.
For my battery, I went to Batteries and Bulbs. They did not charge me anything, even returned my lipo bag.
As others have said, your pad is gone. If you’re struggling to expose the trace needed to solder, it might be easier to find out which one of those test points corresponds to the battery terminal and solder a wire to that instead.
Here’s a great resource I used to repair an Xbox one controller after destroying the pads in an attempt to replace an analogue stick.
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