Simple Photo Enlarger Makes Great Addition To Any Darkroom

Chemical-based photography can seem like a dark art at times, but it needn’t be so. [Dan K] developed the Simple Enlarger to help spread the idea that classical photographic darkroom tools are fundamentally quite easy to understand and build.

The assembled enlarger.

A photographic enlarger illuminates a negative with light, and focuses this light on a sheet of photographic paper which can then be developed. [Dan’s] enlarger design is intended to be built using materials readily available from any dollar store or stationer’s shop, and can be built in just a few short hours. It’s built to work with a single film format and with a fixed size of photographic paper for simplicity’s sake.

A simple M-mount camera lens is pressed into service for the main optic, with the ex-Soviet part chosen for its easy focusing and cheap price. A small plywood box makes a decent body, and a white phosphor LED provides  the light source. The final rig is designed to print 35mm negatives on to standard 8×10 paper.

If you want to get into developing your own negatives and don’t want to buy a commercial enlarger, [Dan]’s build could be just the way to go. We’ve seen some other similar builds before, too. Meanwhile, if you’ve got your own nifty darkroom hacks, be sure to drop us a line!

Remoticon 2021 // Arsenijs Tears Apart Your Laptop

Hackaday’s own [Arsenijs Picugins] has been rather busy hacking old laptops apart and learning what can and cannot be easily reused, and presents for the 2021 Hackaday Remoticon, a heavily meme-loaded presentation with some very practical advice.

Full HD, IPS LCD display with touch support, reused with the help of a dedicated driver board

What parts inside a dead laptop are worth keeping? Aside from removable items like RAM stick and hard drives, the most obvious first target is the LCD panel. These are surprisingly easy to use, with driver boards available on the usual marketplaces, so long as you make sure to check the exact model number of your panel is supported.

Many components inside laptops are actually USB devices, things like touch screen controllers, webcams and the like are usually separate modules, which simply take power and USB. This makes sense, since laptops already have a fair amount of external USB connectivity, why not use it internally too? Other items are a bit trickier: trackpads seem to be either PS/2 or I2C and need a bit more hardware support. Digital microphones mostly talk I2S, which means some microcontroller coding.

Some items need a little more care, however, so maybe avoid older Dell batteries, with their ‘spicy pillow’ tendencies. As [Arsenijs] says, take them when they are ripe for the picking, but not too ripe. Batteries need a little care and feeding, make sure you’ve got some cell protection, if you pull raw cells! Charging electronics are always on the motherboard, so that’s something you’ll need to arrange yourself if you take a battery module, but it isn’t difficult, so long as you can find your way around SMBus protocol.

These batteries are too ripe. Leave them alone.

Older laptops were much more modular and some even designed for upgrade or modification, and this miniaturization-driven trend of shrinking everything — where a laptop now needs to be thin enough to shave with — is causing some manufacturers to move in a much more proprietary direction regarding hardware design.

This progression conflicts with our concerns of privacy, repairability and waste elimination, resulting in closed boxes filled with unrepairable, non-reusable black boxes. We think it’s time to take back some of the hardware, so three cheers to those taking upon themselves the task to reverse engineer and publish reusability information, and long may it be possible to continue.

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The Light Guide Hiding In Your Extrusion

There should be a line of jokes that start “A physicist and an engineer walk into a bar…”. In my case I’m an engineer and my housemate is a physicist, so random conversations sometimes take interesting turns. Take the other day for example, as one does when talking she picked up a piece of aluminium extrusion that was sitting on our coffee table and turned it over in her hands. It has a hole down its centre and it’s natural to peer down it, at which point her attention was caught by the appearance of a series of concentric rings of light. Our conversation turned to the mechanism which might be causing this, and along the way took us into cameras, waveguides, and optical fibres.

The light reaching us after traveling along a straight narrow tube should at a cursory glance be traveling in a straight line, and indeed when I point the extrusion out of my window and look down it I can see a small segment of the tree in the distance I’ve pointed it at. It didn’t take us long to conclude that the concentric rings were successive reflections of the light coming into the end hole from off-centre angles.

In effect, the extrusion is a pinhole camera in which the image is projected onto the inside of a cylinder stretching away from the pinhole rather than onto a flat piece of film, and we were seeing the successive reflections of the resulting distorted image as they bounced to and fro down the tube towards us. It’s likely the imperfect mirror formed by the aluminium wall allowed us to see each image, as light was being diffused in our direction. Adding a piece of tape with a small pinhole at the end accentuated this effect, with the circles becoming much more sharply defined as the projected image became less blurry. Continue reading “The Light Guide Hiding In Your Extrusion”

Glassblowing For The Lab

There was a time when ordering some glassware from a distributor meant making a sizable minimum order, sending a check in the mail and waiting weeks for a box full of — hopefully intact — glassware to arrive. In those days, blowing your own glassware from glass tubes was fairly common and [Wheeler Scientific] has been doing a series on just how to do that. Even if you aren’t interested in building a chemistry lab, you might find the latest episode on making a gas discharge tube worth a watch. There are several videos and you can see a few of them below.

Of course, blowing glass is literally playing with fire, so be careful. Most important rule? Don’t inhale. Then again, for a lot of things, blowing glass doesn’t involve you actually blowing, but it is more like bending and shaping and — technically — what he shows is lampwork, not actual glassblowing, but that’s a technicality.

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Fluke DMM Hack Adds One Digit To Model Number

Among his many interests, [Dave Jones] likes test and measurement equipment. He recently posted a few videos on his EEVblog exploring the reasons why Fluke voltmeters are so expensive. In the process, he stumbled upon an interesting hack for the Fluke 77.

The Fluke 77 was introduced in 1983, and is an average responding meter in the AC modes. This model has become a de-facto standard for use in maintenance depots and labs for equipment which has very long lifespans — think military and industrial gear, for example. Many test procedures and training materials have been designed around the use of the the Fluke 77. The cost to change them when a new and better meter comes along is usually so prohibitive they might as well be cast in stone — or at least hammered into 20 pound fanfold paper by a WordStar-driven daisy-wheel printer. But for those unburdened by such legacy requirements, Fluke has the 17x series of True RMS reading meters from since the beginning of this century. These meters bear a strong visual resemblance to their siblings in the 7x family and are substantially interchangeable but for their AC measurement methods. Continue reading “Fluke DMM Hack Adds One Digit To Model Number”

Reverse Engineering: Trash Printer Gives Up Its Control Panel Secrets

Many of us hardware-oriented types find it hard to walk past a lonely-looking discarded item of consumer electronics without thinking “If only I could lug that back to the car and take it home to play with” and [phooky] from NYC Resistor is no stranger to this sentiment. An old Epson WF-2540 inkjet printer was disassembled for its important ‘nutrients,’ you know, the good stuff like funky motors, encoders and switches. But what do you do with the control panel? After all, they’re usually very specific to the needs of the device they control, and don’t usually offer up much scope for reuse.

The RP2040 PIO is quite capable of pushing out those LCD pixels

[phooky] doesn’t usually bother with them, but this time decided to have a crack at it for fun. Inside, nothing out of the ordinary, with a large single-sided PCB for the key switches and LEDs, and a small PCB hosting the LCD display. The easy part was to figure out how the keyboard scanning was done, which turned out to be pretty simple, it just uses some 74-series shift register devices to scan the columns and clock out the row lines. A Raspberry Pi Pico module was pressed into service to scan the keyboard and enable a keyboard map to be created, by pure brute-force. No need to trace the circuit.

Things got interesting when [phooky] started looking into the LCD interface, based on the Epson E02A46EA chip (good luck finding a datasheet for that one!) and quickly realised that documentation simply wasn’t available, and it would be necessary to do things the hard way. Poking around the lines from the main CPU (an Epson E01A9CA , whatever that is) the display clock was identified, as well as some control signals, and three lines for the RGB channels. By throwing a Saleae data capture into some ROM exploring software, the display configuration was determined to be a standard 320×120 unit.

The PIO unit of the RP2040 was used to generate the video waveforms and push the pixels out to the LCD controller, allowing the RP2040 board to be wired inside the case permanently, converting the control panel into a USB device ready for action!

Want to know a little more about reverse engineering junk (or not) items and repurposing them to your will? Checkout this hacking piece from a couple of weeks back. For something a little more advanced, you could try your hand at a spot of car ECU hacking.

Thanks [Perry] for the tip!

Fixing A Freezer Design Flaw With A Little Bit Of Heat

As a shining example of the law of unintended consequences, [Lou] demonstrates how certain types of freezer/refrigerator combinations fail to work in a cold environment, such as a garage during the winter. As [Lou] points out in his video (also linked after the break) – using the freezer unit in his own garage – the problem lies with devices that put the temperature sensor in the refrigerator section, but circulate cold air starting in the freezer section.

This works great in a home environment with a room temperature comfortable for humans, as the refrigerator will constantly warm up slightly due to heat from the outside, triggering the cooling cycle and ensuring the freezer section will stay nice and cold. When placed in, say, a garage when it’s around freezing, the refrigerator section will not warm up, and thus no more cooling cycle gets triggered.

As obviously the freezer section is supposed to stay significantly colder than roughly around 0°C, the freezer section can warm up enough to allow frozen goods to thaw out. The easy fix here as [Lou] demonstrates, is to add a constant source of warmth inside the refrigerator section, such as by keeping the refrigerator light on constantly.

Obvious complaints about the lack of energy efficiency and this combo unit’s optimistically broken sensor design aside, it is a fairly simple and effective fix. Even so, perhaps trading such a combo unit for one with a dedicated temperature sensor in the freezer section would prevent headaches like these.

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