Dissecting A Mechanical Voltage Regulator

April 20, 2020 by Tom Nardi 55 Comments

When the fuel gauge of his 1975 Triumph Spitfire started going off the scale, the collected knowledge of the Internet indicated that [smellsofbikes] needed to replace a faulty voltage regulator behind the dash. For most people, that would be the end of the story. But he, like everyone who’s reading this right now, really wanted to see what the inside of a 45 year old voltage regulator looked like.

After prying open the metal case, he discovered that not only is the regulator mechanical in nature, but there’s even a tiny screw that allows you to adjust the output voltage. Luckily for us, not only is [smellsofbikes] curious enough to open it up, but he’s also got the tools and knowledge to explain how it works in the video after the break.

Put simply, the heart of the regulator is a bimetallic strip with a coil of wire wrapped around it. When power from the battery is passed through the coil it acts as a heater, which makes the strip move up and break the connection to the adjustable contact. With the connection broken and the heating coil off the strip rapidly cools, and in doing so returns to its original position and reconnects the heater; thus starting the process over again.

These rapid voltage pulses average out to around 10 VDC, though [smellsofbikes] notes that you can’t actually measure the output voltage of the regulator with a meter because it moves around too much to get any sort of accurate reading. He also mentions a unique quirk of this technology: due to the force of gravity acting on the bimetallic strip, the output of the regulator will actually change depending on its mounting orientation.

On the oscilloscope, [smellsofbikes] is able to show us what the output actually looks like. As you might expect, it looks like a mess to 21st century eyes. But these were simpler times, and it should go without saying there aren’t any sensitive electronics in a sports car from 1975. Interestingly, he says he’s now replaced the mechanical assembly with a modern regulator chip. Here’s hoping we’re around long enough to see if he gets another 50 years out of it.

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Using A Voltage Regulator As A Constant Current Source

July 4, 2015 by Nava Whiteford 77 Comments

[Afroman] contacted us to share his new video on the LM317. The humble LM317 adjustable voltage regulator is everywhere. From wifi routers, to high spec lab equipment. Given a noisy input and a variable load, a voltage regulator will give a nice clean, stable output voltage. We’ve covered the basic operation and usage of the LM317 many times. But even the most common of parts can be used in new and interesting ways.

In his video [Afroman] describes how the LM317 can be used to regulate current rather than voltage to provide a constant current source under varying load. This can useful for a number of applications including driving LEDs and laser diodes. While this circuit may not be as efficient as an LED driver module or a switching solution the LM317 is cheap and readily available. [Afroman] also describes how the circuit works in detail allowing us to enjoy this ubiquitous part in this slightly unusual application.

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Homemade E-Cigarette Vaporizer

September 13, 2014 by Matt Terndrup 157 Comments

Extensive research shows that tobacco kills. This is common knowledge as of late, which has prompted a flurry of anti-smoking ads to flood in. Regular smokers are now reconsidering their smoking patterns and are looking at healthier alternatives. Among those options are electronic cigarettes that vaporize flavorful liquid into smooth drags of smoke.

Prices for these devices can range anywhere from $40 to $240, which can be quite expensive for those on a budget. So instead of buying one, [MrRedBeard] decided to create his own DIY electronic cigarette contraption out of an Altoids can.

The approximate cost (not including batteries) is about $12. This covers the 5 Amp adjustable voltage regulator and the 500 ohm potentiometer that is best used for a rig like this. The wattage is what drives the heat giving it a more consistent vapor stream of cloud smoke.

For more e-cigarette hacks, check out these ones powered by an NES controller and this vaporizer that can send smells…in space!

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25th Chaos Communication Congress Schedule

November 24, 2008 by Eliot 7 Comments

The team behind 25C3 has published the first draft of this year’s schedule. The annual Chaos Communication Congress is happening December 27th to 30th in Berlin, Germany. There are plenty of interesting talks already in place. We’re spotting things we want to attend already: The conference starts off with how to solar power your gear, which is followed by open source power line communication. A TOR-based VPN, an open source BIOS, rapid prototyping, holographic techniques, and running your own GSM network are on the bill too.

We’ll have at least three Hack a Day contributors in attendance. Last year featured two of our favorite conference talks: [Drew Endy]’s Biohacking and the MiFare crypto1 RFID crack. We hope to see you there.

Adjustable Breadboard Power Supply

November 8, 2008 by Eliot 14 Comments

psboard

This looks like a great addition to your breadboard. [Nerdz] wanted a power supply that was easily portable and adjustable. He built a custom board that plugs directly into the breadboard’s power rails. It has a pot attached to the ground of a 7805 voltage regulator so the output can be adjusted from 5V to just under the supply voltage. Anything that makes a breadboard less of a rats nest is definitely a good thing.

Parts: LM317 Adjustable Voltage Regulator

September 22, 2008 by Ian 35 Comments

Every project needs a power supply. As 3.3volt logic replaces 5volt systems, we’re reaching for the LM317 adjustable voltage regulator, rather than the classic 7805. We’ve found four different hobbyist-friendly packages for different situations.

A simple voltage divider (R1,R2) sets the LM317 output between 1.25volts and 37volts; use this handy LM317 calculator to find resistor values. The regulator does its best to maintain 1.25volts on the adjust pin (ADJ), and converts any excess voltage to heat. Not all packages are the same. Choose a part that can supply enough current for your project, but make sure the package has sufficient heat dissipation properties to burn off the difference between the input and output voltages.

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