I'm not sure I understand what you are trying to do... do you want to build a radio? Or are all your signals in the audio range?
Anyway:
Regarding Gilbert cells, the two popular chips are MC1496 and SA631. The 631 comes with a built-in oscillator, so it's quite handy. Unfortunately both are hard to come by these days.
Does this mean jd vance is a centipede?
Heresy! Australia will always be a planet.
Damn, i was hoping for them to make it slower!
I can only find pictures of 6-lobed Gamebit screws
EDIT: I believe I found the answer, it's something turned by this: https://ctatools.com/products/5065
Found some trash on the street that i'd like to take apart, but this screw is in my way.
It's like a hex bolt, but with 5 sides, and rounded (a bit like flower petals).
Here's another picture from the top:
I tried turning it with various tools (hard to get pliars in unfortunately), no success so far. The material is very soft, which doesn't help..
Growing plants with LEDs certainly works, I'm just wondering if the power of a USB port is enough
there's no need for relays if you have low voltage
That's a good point. Also makes me wonder if those lights will actually make a difference when it comes to plant growth, given the low power.
It's not completely stupid. One pissible issue: when the light level is around the threshold, slight variations (think: cloud passing by) will cause the relay to switch back and forth quickly. This can be solved with some additional parts (keyword: hysteresis).
I would recommend using a microcontroller, it makes this problem easy to solve, plus you can have more logic to trigger the lights (eg time based).
Another thing is turning off: if it's purely based on light level, you need to make sure the sensor does not "see" any of the LED light, otherwise it thinks the sun is back up
The only winning move is to cook a nice curry, because plain rice is just boring.
Can someone explain to a european why this huge chunk of the eastern half of the country is called "midwest"?
I can't recall a time when I wasn't lost in the inner solar system. Currently I'm stuck on the third dot - how do I proceed?
Alt
The picture shows today's XKCD comic.
Transcript:
[A grayed-out sentence in the Times New Roman font reads "Optimistic aliens measure space typographically". The "O" in "Optimistic" is dark black and indicated as representing the Sun (not to scale). The dots of the letters "i" in the sentence are similarly dark black. The dot in the first "i" in "Optimistic" is indicated as representing Mercury; the dot in the second "i" represents Venus; the dot in the third "i" represents Earth. The dot in the "i" in "aliens" is indicated as representing Mars. The dot in the "i" in "typographically" is indicated as representing Jupiter. A measurement bar indicates that the distance between the "O" and the third "i" in "Optimistic" is equivalent to 1 AU (astronomical unit).]
[Caption below the panel:]
Space tip: if you're ever lost in the inner Solar System, you can just type out the phrase "Optimistic aliens measure space typographically" in Times New Roman and use the dots as a map.
I am powering a 5V microcontroller (arduino clone, atmega328p) using a 9V block and a buck converter. Now I want to let the microcontroller occasionally measure the battery voltage, so I can get an idea of how full it is.
My first idea was to use a simple voltage divider:
I've chosen the resistor values so that:
< 1.1V, to be able to use the 1.1V internal reference of the atmega's ADCR1 || R2 < 10kΩ, since the atmega datasheet says "The ADC is optimized for analog signals with an output impedance of approximately 10 kΩ or less"This is great and all, but what bothers me is that this circuit will constantly draw ~100µA from the battery.
So, my next thought was to add a mosfet to the divider, to switch it on only while measuring:
This is obviously bad, because now when the mosfet is off, the ADC input sees the whole battery voltage.
To address that issue, I've added a second mosfet into the measure path:
This works, and it does not draw any current, except while measuring.
However, it's quite a few parts. So I'm curious if anyone has an idea how to do this with just a single mosfet. It seems to me like it should be possible, but I haven't figured out how.
Oh, and if I'm doing something stupid here, please tell me :)
I have a whole bunch of them. They are possibly a bit older (70s, 80s) judging by other contents of the junk box they are from.
There are no labels of any kind, but on the top they have stripes that look hand painted.
For at least some of them the resistance roughly corresponds to the color code.
So, I'm just curious why I can't find anything about these on the internet.
Great, good luck with that :)
Another thing that comes to mind: for audio purposes another technique used in ring modulators for audio effects is to use a mosfet switch to mix the signal with a square wave. This has more byproducts than mixing with a pure sine, but is a lot easier to do. Since you are downconcerting, it should not matter at all if you use a square wave, since the byproducts will all be (higher-order) harmonics of the local oscillator, which you'll filter out anyway.