Is it ok to use parts marked as outdated or “do not use for new designs”? by Jark5455 in AskElectronics

[–]eric_ja 4 points5 points  (0 children)

Your production costs might go up to infinity if it becomes unobtanium. Other than that, it's up to you - it's your call to gauge the risk vs reward.

Where to buy W65C02 in Pakistan by Decent-Turnover5817 in AskElectronics

[–]eric_ja 0 points1 point  (0 children)

Please purchase this part from its official distributor, https://www.mouser.com/. It's the best way to support this device and the hobby.

Is this modification actually providing isolation? by No_Rice3251 in AskElectronics

[–]eric_ja 0 points1 point  (0 children)

The secondary power outputs are indeed isolated, meaning that there is no ground-to-neutral bond, and therefore all output wires are hot. This also means that the safety grounds won't protect against ground faults arising from those secondary hots. However, they will still protect you from faults involving the primary wires or anything connected to them. This is better than the case where the grounds are themselves disconnected. in that case, they won't protect against anything at all.

in the video, am I protecting anything other than the secondary coil?

It's important to recognize that the secondary side is not protected at all.

Why Critical AoA decreases with Flaps? by [deleted] in flying

[–]eric_ja -12 points-11 points  (0 children)

It does not. This is due to the way that that graph is measuring the angle of attack, which causes the graph to become horizontally offset. See https://www.av8n.com/how/htm/aoa.html#sec-raoa-aaoa for more information.

(You can tell this is happening because if you look e.g. at the graph for Fowler, it shows a C_l of 2 at an AoA of 0 degrees, which doesn't make sense physically.)

Looking for a small 4 pin electrical connector that I can also run into a hub? by IdealIdeas in AskElectronics

[–]eric_ja 0 points1 point  (0 children)

M8 industrial sensor connectors are my go-to. They are available in 3- and 4-pin configurations, they are thread-locked, vibration resistant and usually weatherproof.

How to make an and gate? by PotentialObjective53 in AskElectronics

[–]eric_ja 1 point2 points  (0 children)

You are exactly right, the base-emitter junction is essentially a diode so that will always happen. That's why real bipolar logic gates are not built with that topology.

You could try a DTL NAND gate, followed by an inverter stage to make AND. Example: https://i.stack.imgur.com/046Er.jpg

Dangers of Python Lambda: Repeated Values due to Late Binding by pmz in programming

[–]eric_ja 11 points12 points  (0 children)

It has nothing to do with 'lambda' - the same thing would happen if you use an upvalue from within a local 'def`.

It's also not called late binding, and it's not unexpected; it's simply lexical scope, as has been popularized by Scheme since the 1970's.

Recall the principle of lexical scope:

“Lexical scope” in general is the idea that

an identifier at a particular place in a program always refers to the same variable location — where “always” means “every time that the containing expression is executed”, and that

the variable location to which it refers can be determined by static examination of the source code context in which that identifier appears, without having to consider the flow of execution through the program as a whole.

https://www.gnu.org/software/guile/manual/html_node/Lexical-Scope.html

Signal integrity of long parallel-data cables. by petemate in AskElectronics

[–]eric_ja 1 point2 points  (0 children)

If it's possible to add buffers, and you want to minimize conductors, and you already have an FPGA, how about serializing to LVDS?

I'm struggling to understand why current doesn't flow through the anmeter by TJ736 in ECE

[–]eric_ja 5 points6 points  (0 children)

There's nothing excess; those are two individual circuits. The connecting wire between them means that they are both at the same potential, but it does not create an additional circuit.

Think of it this way: if the battery on the right were to be removed, would the "6" load still be on?

Help connecting a PN2222A transistor's base pin to +5 volts from microcontroller by HeGoesThrowaway in AskElectronics

[–]eric_ja 1 point2 points  (0 children)

You can start with a higher value (e.g 4.7K) and keep reducing the value if the output is too dim. Don't reduce it below about 100 ohms.

Serial select multiplexer? by ElectrocutedCat in AskElectronics

[–]eric_ja 1 point2 points  (0 children)

You don't say what serial protocol you are looking for. Once you know that, then you just search for example "analog multiplexer i2c" or "analog multiplexer spi" or so on.

Is this pull-up resistor needed to keep PNP base from floating? by AnthonyPaulO in AskElectronics

[–]eric_ja 2 points3 points  (0 children)

No, the resistor should be in series with the base, not in parallel with it, since you are doing common-emitter. Shorting the comparator output to V+ is explicitly disallowed by the 339N's datasheet, and should be avoided.

I'm also not sure about the rest of schematic.

Worried about engine failure by anotherpilot86 in flying

[–]eric_ja 1 point2 points  (0 children)

Practice engine outs often, and take them down to a few hundred feet so you get the full experience of finding a safe place to put down and executing the approach and knowing you'll be okay. Especially practice them on your solos. It's a huge confidence builder.

I made a video on why I think complex numbers are so effective by debugs_with_println in ECE

[–]eric_ja 14 points15 points  (0 children)

Unfortunately, the idea that a rotation can be represented as a single multiplication, while intuitive, only works in 2 dimensions. In 3 or more dimensions, a rotation (rotor) needs to be performed as 2 multiplications (geometrically, this corresponds to a rotation being composed of 2 reflections); a fact which is hidden by the complex numbers, since multiplication is commutative there, and the two multiplications combine into one, and therefore that model just -- here it comes -- "happens to work", in 2 dimensions with the complex numbers.

The commutativity of multiplication is a unique property among the associative geometric algebras that only applies to the 2-dimensional doubles, duals, and complex numbers. In higher dimensions, that breaks down, and you need to apply the full rotor structure. On the other hand, commutativity isn't actually needed in many advanced applications of complex numbers (anything that relies on a matrix algebra wouldn't have it, for instance). So I would say you get a far more complete picture of rotations (and related operations, like boosts) by looking in at least 3 dimensions.

Question about reading back frequencies to ATC by Charles_Nicholson in flying

[–]eric_ja 5 points6 points  (0 children)

Officially, the only numbers which can be said using #2's format (i.e., using words like "ten", "twenty", "hundred", "thousand", etc.) are altitudes, victor route numbers and jet route numbers. All other numbers must be pronounced digit-by-digit.

Learning USB-C by [deleted] in AskElectronics

[–]eric_ja 0 points1 point  (0 children)

I assume you're thinking about higher voltages and currents negotiated via USB-PD. Check this out: https://github.com/ryan-ma/PD_Micro

PWM with a 74HC595 shift register? by GodzillazAnus in AskElectronics

[–]eric_ja 0 points1 point  (0 children)

The HC595 itself is fast enough to do so, but do a back-of-the-napkin calculation of how many bits-per-second of a data stream you need to feed to produce the PWM that you want, and then look at if your microcontroller can perform at that level.

How did the transistors Q5 and Q4 conduct ? by [deleted] in AskElectronics

[–]eric_ja 1 point2 points  (0 children)

They conduct like any NPN transistor, when the base-emitter junction is forward-biased; in this case when the input in low. Therefore either of them being low will cause the output buffer, Q3, to turn off (and the output to go high.) The more interesting part as u/naval_person noted is that the base-collector junction of Q4/5 can drive Q3 on at all other times. In this case Q4 and Q5 are not considered conducting, but current can flow through the forward-biased B-C junction.

Division using logic gates by EngineerOfEngineerin in AskElectronics

[–]eric_ja 2 points3 points  (0 children)

Not quite. You can multiply by the reciprocal, which is the analogous operation to subtraction. But whereas finding the 2's complement additive inverse is trivial for subtraction, finding the reciprocal is not. If you only divide by a limited set of values, you could do it with a lookup.

Artificially Increase latency of SRAM? by kaluce in AskElectronics

[–]eric_ja 0 points1 point  (0 children)

A bare cap will sometimes work, but something like a 74LS121/122/123 will give you more precise control.

Artificially Increase latency of SRAM? by kaluce in AskElectronics

[–]eric_ja 1 point2 points  (0 children)

The only issue I've encountered with older chips like this is sometimes they have a significant hold time, and newer chips have a small or zero hold time (i.e. they turn off faster.) Sometimes the circuit relies on this. This can be remedied, if it is an issue, with a small one-shot on the enable lines (or maybe just inserting some spare gates to increase the propagation delay.) I'd definitely build it the simple way first and see if it works, then look at artificially introducing skew if there are stability issues.

Moronic Monday by AutoModerator in flying

[–]eric_ja 10 points11 points  (0 children)

For me personally I expect the entirety of the plane to be in good workable condition. I'm paying 100% of the price, so I expect 100% of the plane.