Simple Electronic Hacks Inspire Doing More With Less

October 26, 2021 by Ryan Flowers 18 Comments

It’s late at night. The solder smoke keeps getting in your tired eyes, but your project is nearly done. The main circuit is powered by your 13.8 V bench supply, but part of the circuit needs 9 V. You dig into your stash to find your last LM7809 voltage regulator, but all you have is a bunch of LM7805’s. Are you done for the night? Not if you’ve watched [0033mer]’s Simple Electronic Circuit Hacks video! You know just what to do. The ground pin of a LM7805 connects to the cathode of a TL431 programmable Zener diode pulled from an old scrapped TV. The diode is referenced to a voltage divider, and voila! Your LM7805 is now putting out a steady 9 V.

How did [0033mer] become adept at doing more with less? As he explains in the video below, his primary source of parts in The Time Before The Internet was old TV’s that were beyond repair. Using N-Channel MOSFETs to switch AC, sensing temperature changes with signal diodes, and even replacing a 555 with a blinking LED are just a few of the hacks covered in the video below the break.

We especially appreciated the simple, to-the-point presentation that inspires us to keep on hacking in the truest sense: Doing more with less! If you enjoy a good diode hack like we do, you will likely appreciate learning Diode Basics by W2AEW, or a Diode Based Radiation Detector.

Thank you [DSM] for the tip! Be sure to submit your the cool things you come across to our Tips Line!

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What Goes Into A High Voltage Diode?

October 3, 2021 by Jenny List 12 Comments

When we use an electronic component, we have some idea of what goes on inside it. We know that inside a transistor there’s a little piece of semiconductor with a junction made from differently doped regions etched into it, and in a capacitor, there will be metalized plates on the surface of some kind of dielectric. Reverse engineering has given us extensive die photography of integrated circuits, but there remain a few component mysteries to be uncovered. One is laid bare by [WizardTim], as he cross-sections a 20KV high-voltage diode.

A conventional low-voltage silicon diode has a forward voltage drop of about 0.7V and a relatively low maximum reverse voltage, for example with the 1N4001 rectifier it’s 50V. For the higher-spec 1N4007, the reverse voltage rating is 700V. This diode has a 25KV reverse voltage, and a clue to its construction comes in its quoted 45V forward voltage. Sure enough, when mounted in resin and carefully sanded and polished flat it reveals its interior as a stack of diodes in series to increase the reverse voltage at the expense of forward voltage.

Revealing the inner workings of an unusual component is fascinating, and the lapping technique used is definitely worth a look. It’s something we’ve seen before, for example in reducing CPU thickness for increased performance.

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Reverse Engineering A Module From A Vacuum Tube Computer

September 10, 2020 by Dan Maloney 32 Comments

It’s best to admit upfront that vacuum tubes can be baffling to some of the younger generation of engineers. Yes, we get how electron flow from cathode to anode can be controlled with a grid, and how that can be used to amplify and control current. But there are still some things that just don’t always to click when looking at a schematic for a tube circuit. Maybe we just grew up at the wrong time.

Someone who’s clearly not old enough to have ridden the first wave of electronics but still seems to have mastered the concepts of thermionic emission is [Usagi Electric], who has been doing some great work on reverse engineering modules from old vacuum tube computers. The video below focuses on a two-tube pluggable module from an IBM 650, a machine that dates clear back to 1954. The eBay find was nothing more than two tube sockets and a pair of resistors joined to a plug by a hoop of metal. With almost nothing to go on, [Usagi] was still able to figure out what tubes would have gone in the sockets — the nine-pin socket was a big clue — and determine that the module was likely a dual NAND gate. To test his theory, [Usagi] took some liberties with the original voltages used by IBM and built a breakout PCB. It’s an interesting mix of technologies, but he was able to walk through the truth table and confirm that his module is a dual NAND gate.

The video is a bit long but it’s chock full of tidbits that really help clear up how tubes work. Along with some help from this article about how triodes work, this will put you on the path to thermionic enlightenment.

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Tiny Laser Cutter Puts Micro Steppers To Work

June 3, 2020 by Dan Maloney 33 Comments

The influx of cheap laser cutters from China has been a boon to the maker movement, if at the cost of a lot of tinkering to just get the thing to work. So some people just prefer to roll their own, figuring that starting from scratch means you get exactly what you want. And apparently what [Mike Rankin] wanted was a really, really small laser cutter.

The ESP32 Burninator, as [Mike] lovingly calls his creation, is small enough to be in danger of being misplaced accidentally. The stage relies on tiny stepper-actuated linear drives, available on the cheap from AliExpress. The entire mechanical structure is two PCBs — a vertical piece that holds the ESP32, an OLED display, the X-axis motor, and the driver for the laser, which comes from an old DVD burner; a smaller bottom board holds the Y-axis and the stage. “Stage” is actually a rather grand term for the postage-stamp-sized working area of this cutter, but the video below shows that it does indeed cut black paper.

The cuts are a bit wonky, but this is surely to be expected given the running gear, and we like it regardless. It sort of reminds us of that resin 3D-printer small enough to fit in a Christmas ornament that [Sean Hodgins] did a while back. We’d suggest not trying to hang this on a tree, though.

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Diode Basics By [W2AEW]

November 11, 2019 by Al Williams 8 Comments

We didn’t think we needed a basic guide to diodes until we saw it was from [W2AEW], and then we knew we’d pick up some new things. Entitled “Diodes from Ideal to Real” the 18-minute video doesn’t disappoint with a mix of notes and time with a curve tracer to learn all about these devices.

As is typical for a [W2AEW] video this doesn’t just cover the simple operation of diode. It includes topics such as dynamic resistance, junction capacitance, and talks about a wide variety of diode types.

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Negative Voltage Pushes AVR To New Heights

December 8, 2018 by Tom Nardi 38 Comments

If we say that a hacker is somebody who looks at a “solved” problem and can still come up with multiple alternative solutions, then [Charles Ouweland] absolutely meets the grade. Not that we needed more evidence of his hacker cred given what we’ve seen from him before, but he recently wrote in to tell us about an interesting bit of problem solving which we think is a perfect example of the principle. He wanted to drive a salvaged seven segment LED display with an AVR microcontroller, but there was only one problem: the display needs 15V but the AVR is only capable of 5V. So what to do?

As it turns out, the first step to solving the problem was verifying there was actually a problem to begin with. [Charles] did some experimentation and found that the display didn’t actually need 15V to operate, and in fact would light up well enough at just 6.5V. This lowered the bar quite a bit, but it was still too high to power directly from the chip.

There were a few common ways to solve this problem, which no doubt the Hackaday reader is well aware of. But [Charles] wanted to take the path less traveled. More specifically, the path with the least amount of additional components he had to put on his PCB. He set out to find the absolute easiest way to make his 5V AVR light up a 6.5V LED, and ended up coming with a very clever solution that some may not even know is possible.

He reasoned that if he connected the source pins of two BS170 MOSFETs to a voltage of -1.5V, even when the AVR pin was 0V, they would be still be receiving 1.5V. This virtual “step ladder” meant that once the AVR’s pin goes high (5V), the relative voltage would actually be 6.5V and enough to drive his LEDs. Of course the only problem with that is that you need to have a source for -1.5V.

Getting a negative voltage would normally require adding more components to the design (which he set out to avoid in the first place), but then he came up with another clever idea. To pull the trick off, he actually feeds the AVR 6.5V, but raises the ground voltage by 1.5V with the addition of two 1N4007 diodes. This way the AVR gets a voltage within its capabilities and still can provide a relative 6.5V to the LEDs.

One might say [Charles] took the Kobayashi Maru approach, and simply redefined the rules of the game. But such is the power of the confounding negative voltage.

Science Shows Green Lasers Might Be More Than You Bargained For

August 31, 2018 by Dan Maloney 54 Comments

This may come as a shock, but some of those hot screaming deals on China-sourced gadgets and goodies are not all they appear. After you plunk down your pittance and wait a few weeks for the package to arrive, you just might find that you didn’t get exactly what you thought you ordered. Or worse, you may get a product with unwanted ~~bugs~~ features, like some green lasers that also emit strongly in the infrared wavelengths.

Sure, getting a free death ray in addition to your green laser sounds like a bargain, but as [Brainiac75] points out, it actually represents a dangerous situation. He knows whereof he speaks, having done a thorough exploration of a wide range of cheap (and not so cheap) lasers in the video below. He explains that the paradox of an ostensibly monochromatic source emitting two distinct wavelengths comes from the IR laser at the heart of the diode-pumped solid state (DPSS) laser inside the pointer. The process is only about 48% efficient, meaning that IR leaks out along with the green light. The better quality DPSS laser pointers include a quality IR filter to remove it; cheaper ones often fail to include this essential safety feature. What wavelengths you’re working with are critical to protecting your eyes; indeed, the first viewer comment in the video is from someone who seared his retina with a cheap green laser while wearing goggles only meant to block the higher frequency light.

It’s a sobering lesson, but an apt one given the ubiquity of green lasers these days. Be safe out there; educate yourself on how lasers work and take a look at our guide to laser safety. Continue reading “Science Shows Green Lasers Might Be More Than You Bargained For” →