Category Archives: resistor

How Current Shunts Work

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Current. Too little of it, and you can’t get where you’re going, too much and your hardware’s on fire. In many projects, it’s desirable to know just how much current is being drawn, and even more desirable to limit it to avoid catastrophic destruction. The humble current shunt is an excellent way to do just that.

To understand current, it’s important to understand Ohm’s Law, which defines the relationship between current, voltage, and resistance. If we know two out of the three, we can calculate the unknown. This is the underlying principle behind the current shunt. A current flows through …read more

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Error: LP0 On 🔥

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You don’t need fancy ICs and DACs to build a sound card for a PC. As [serdef]’s build over on hackaday.io shows, all you really need is a bunch of resistors. [serdef] built a clone of a sound card released for PC in the 80s, but with a few improvements. This mess of resistors features the best 8-bit sound you can get with a low-pass filter, volume divider, and a handy DB-25 connector.

The design of this LPT0 sound card is pretty much the same as when it was introduced to the world as the Covox Speech Thing. This ‘sound …read more

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Error: LP0 On 🔥

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You don’t need fancy ICs and DACs to build a sound card for a PC. As [serdef]’s build over on hackaday.io shows, all you really need is a bunch of resistors. [serdef] built a clone of a sound card released for PC in the 80s, but with a few improvements. This mess of resistors features the best 8-bit sound you can get with a low-pass filter, volume divider, and a handy DB-25 connector.

The design of this LPT0 sound card is pretty much the same as when it was introduced to the world as the Covox Speech Thing. This ‘sound …read more

Continue reading Error: LP0 On 🔥→

Hackaday Trims Its Own Resistors

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There are times when you might want an odd-value resistor. Rather than run out to the store to buy a 3,140 Ω resistor, you can get there with a good ohmmeter and a willingness to solder things in series and parallel. But when you want a precise resistor value, and you want many of them, Frankensteining many resistors together over and over is a poor solution.

Something like an 8-bit R-2R resistor-ladder DAC, for instance, requires seventeen resistors of two values in better than 0.4% precision. That’s just not something I have on hand, and the series/parallel approach will get …read more

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Automatic Resistance: Resistors Controlled by the Environment

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Resistors are one of the fundamental components used in electronic circuits. They do one thing: resist the flow of electrical current. There is more than one way to skin a cat, and there is more than one way for a resistor to work. In previous articles I talked about fixed value resistors as well as variable resistors.

There is one other major group of variable resistors which I didn’t get into: resistors which change value without human intervention. These change by environmental means: temperature, voltage, light, magnetic fields and physical strain. They’re commonly used for automation and without them our …read more

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Resistance in Motion: What You Should Know About Variable Resistors

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Adjusting the volume dial on a sound system, sensing your finger position on a touch screen, and knowing when someone’s in the car are just a few examples of where you encounter variable resistors in everyday life. The ability to change resistance means the ability to interact, and that’s why variable resistance devices are found in so many things.

The principles are the same, but there are so many ways to split a volt. Let’s take a look at what goes into rotary pots, reostats, membrane potentiometers, resistive touchscreens, force sensitive resistors, as well as flex and stretch sensors.

Potentiometer

…read more

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What is There to Know About Resistors?

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Resistor: A passive chunk of material that resists the flow of electrical current. A terminal is connected to each end you’re done. What could be simpler?

It turns out it’s not so simple at all. Temperature, capacitance, inductance and other factors all play a part in making the resistor a rather complex component after all. Even its uses in circuits are many, but here we’ll just focus on the different types of fixed-value resistors, how they’re made, and what makes them desirable for different applications.

Let’s start with a simple one, and one of the oldest.

Carbon Composition

These are …read more

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