Kuba hasn't forgotten Monica
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Do ‘wiperless’ potentiometers exist?
41 votes

How to get the most out of a potentiometer? In many precision, low-noise designs, it's a bad idea to start with to even have the signal routed through the front panel. So, at the very least, the ...

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What is the purpose of the fenced-off area on this board?
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29 votes

The holes in the board reduce electrical leakage, provide mechanical strain relief, and reduce thermal coupling and externally induced thermal gradients. Overview Let's start with leakage. Remember ...

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Is there any advantage or disadvantage of using high value capacitor instead of high value resistor in filter?
Accepted answer
15 votes

is there any disadvantage of using a high-value resistor with a low-value capacitor or vice versa? Yes. High impedance brings to mind: High-value resistors create high-impedance nodes. That wouldn't ...

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Silicon-free amplifier
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14 votes

TL;DR: Any sort of a relay computer with integrated stored program memory (not paper tape) is a small-scale production run no matter how much one wishes it to be just a "one off" experiment. ...

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Hack for fitting 0.04" leads in to a 0.025" hole on PCB
10 votes

You could trim the leads short, and solder thinner solid wire to the stub leads. If you want good reliability, you should wind one end of the thinner wire on the stub leads or a slightly oversize ...

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Inability to forward bias diode in a simple circuit
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8 votes

Diode is not the problem. You can remove it and replace it with a piece of wire to see that for yourself. Make a simpler circuit work first. Then when you add the diode it'll keep on working (as long ...

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Is this a zero ohm resistor?
Accepted answer
7 votes

It's hard to tell definitely what it is without measuring its complex impedance at several frequencies. If you do any sort of component-level repair, having a network analyzer with a component test ...

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How to connect a flex ribbon cable to a screw terminal block?
7 votes

run flex ribbons from the PCB to all 4 screw terminal block Why? You're only doing the modification once, so you're probably spending more time thinking about it than will take to assemble it :) The ...

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USB Shield. To ground or not to ground?
7 votes

Good shielding simply means good shield continuity. The PC board usually doesn't even figure in any of it - for shield continuity, you should mentally replace the board with an insulator. For purpose ...

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Can an electric circuit do recursion?
Accepted answer
7 votes

First we need to decide what recursion really is. When you take a recursive function, there may exist a transformation that gets rid of the recursion, but introduces state. In other cases, the ...

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Reduce noise from a Hall effect sensor
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7 votes

There are several problems, some of which are mentioned in other answers. I'll reiterate them for completeness's sake: The Arduino's output is loaded with the mosfet's gate capacitance. That can be ...

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How different are 8-bit microcontrollers from 32-bit microcontrollers when it comes to programming them
6 votes

The biggest practical difference is the amount of documentation, really, to entirely understand the entire chip. There are 8-bit microcontrollers out there that come with almost a 1000 pages of ...

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What's the most effective way to prevent EM noise from coupling onto a cable and radiating out?
Accepted answer
6 votes

Shields must generally be connected, across 360 degrees of the opening, directly to the enclosure. Any connectors and connector shells used must maintain such multipoint, all-around connection. ...

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Are anodized fan filters efficient at blocking EMI?
5 votes

There needs to be continuous contact between the screen, the frame, and the enclosure this thing is mounted on, along the entire circumference of the opening. Outside of this conductive ...

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Can a 12V relay coil handle 350mA passing through it?
Accepted answer
5 votes

You're trying to use the relay as a current sensor. That's of course possible, but it requires a low voltage relay that has a low coil resistance. For example, suppose that your sensing relay would be ...

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Dealing with negative inductor in filter design
Accepted answer
5 votes

This is a very typical result that basically means you got a garbage output, because something overflowed in the filter synthesis computations, or there was catastrophic loss of precision, or some ...

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How to carry quadrature encoder data using a single signal?
5 votes

One solution is to convert the encoder's binary digital output to a quaternary (4-valued) digital signal. It uses only 4 resistors. The only reasonable values for such a circuit that yield uniformly ...

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Why is USB cable maximum length is shorter than in RS232?
5 votes

It's not really possible to "buffer" USB, at least not in the usual sense of the word. Typically, buffering means electrical amplification and perhaps signal regeneration. With USB, the host drives ...

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Analog isolation vs Digital Isolation
5 votes

Given the ridiculously low prices of MCUs with decent on-board ADCs, the simplest way to do it would be to do digital isolation between MCUs. Simply treat a small single-chip microcontroller as a "...

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Decoupling caps, PCB layout
5 votes

There's a yet another trick in minimizing the impedance between the internal GND and VCC rails in the MCU, and the power planes. Every unused MCU I/O pin should be connected to either GND or VCC, ...

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What type of regulator to use? (switching or linear)
4 votes

A synchronous switcher to drop 15V down to 6V. Shoot for 250kHz+. A "pi" C-L-C filter consisting of switcher's output capacitor, LDO's input capacitor, and a series inductor, plus a small ...

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How are CAN Identifier value assigned in CAN communication?
4 votes

CAN co-mingles the message ID and priority. Message IDs imply the priority, but have no other low-level meaning if you look only at the basic CAN protocol layer 1 and 2 given in ISO 11898-1 (with very ...

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Is a "magneto-dynamic" pickup possible?
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4 votes

All you're asking is whether the magnetizing field in a pick-up can be generated by an electromagnet and thus made variable. Sure - it's possible, and furthermore the separation of the coils is ...

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10Gb link data transfer between FPGA && PC
4 votes

initiate the 10G protocol to initiate the link between the FPGA and PC to achieve successful data streaming without data loss. There's not much to "initiate" at the link level: as soon as ...

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Why Gerber Viewers are slow to display, zoom, and pan?
4 votes

They are slow to display mainly because the implementations of most Gerber viewers: Don't treat geometry as geometry, but as primitives that are to be left alone. Are single threaded. Don't use ...

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Physically, what is and how to, make an anti pad?
4 votes

This is a case of a lot of ado about nothing, almost. Ott's style is unfortunately overly verbose at times, and the drawings are, frankly, atrociously confusing. An anti-pad is simply the hole in the ...

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Multiplexing analog signal
Accepted answer
4 votes

I don't think that multiplexing raw pH inputs using analog switches is such a cool idea. They are high impedance, and the probes can be destroyed if the muxes latch up due to ESD etc. It won't cost a ...

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Replacing a tactile switch with an ultrasonic ranger
Accepted answer
4 votes

A simple comparator circuit will do: simulate this circuit – Schematic created using CircuitLab U1 can be a slow, rail-to-rail CMOS part that costs under $1 - either a general purpose op-amp, ...

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SPI chip select --> data + clock delay tolerance
Accepted answer
4 votes

It goes the opposite way: the delay must be no shorter than a certain value, usually a couple hundred ns. Moreover, it's the delay between assertion of CS and the first edge of the clock signal. It ...

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Unused twisted pair termination with RS-485 on 8P8C
Accepted answer
4 votes

You must provide a common potential reference, so you need at least one pair for simplex data and one wire for common/GND. Just because it's differential transmission doesn't mean you only need two ...

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