# This DIY Turntable Just Got Freaky Fresh

Photography turntables are made for both the precise and lazy. Whether you are concerned about the precision of consistent angles during a photo shoot or you simply do not want to stand there rotating a plate after every picture — yes, it does get old — a lazy susan style automatic photography turntable is the ticket. This automatic 360° design made over at circuito.io satisfies both of these needs in an understated package

The parts required to make this DIY weekend project are about as minimal as they get. An Arduino Uno controls it all with a rotary encoder for input and a character LCD to display settings. The turntable moves using a stepper motor and an EasyDriver. It even takes care of controlling the camera using an IR LED.

The biggest obstruction most likely to arise is creating the actual laser cut casing itself. The circuito team avoided this difficulty by using Pololu‘s online custom laser cutting service for the 4 necessary laser cut parts. After all of the components have been brought together, all that is left to do is Avengers assemble. They provide step by step instructions for this process in such a straightforward way that you could probably put this sucker together blindfolded.

We have seen some other inspired photography turntables on Hackaday before. [NotionSunday] created a true turntable hack based off of the eject mechanism of an old DVD-ROM drive. With the whole thing spinning on the head assembly of a VCR, this is the epitome of letting nothing go to waste. We also displayed another very similar Arduino Uno controlled turntable created 2 years ago by [Tiffany Tseng]. There is even a non-electronic version out there of a DIY 360° photography turntable that only uses a lazy susan and tape measure. All of these photography turntable hacks do the job wonderfully, but there was something that we liked about the clean feel of this one. All of the necessary code for this project has been provided over at GitHub. What is your favorite photography turntable?

# DIY Capacitive Rotational Encoder on the Cheap with FR4

Rotary encoders are critical to many applications, even at the hobbyist level. While considering his own rotary encoding needs for upcoming projects, it occurred to [Jan Mrázek] to try making his own DIY capacitive rotary encoder. If successful, such an encoder could be cheap and very fast; it could also in part be made directly on a PCB.

The encoder design [Jan] settled on was to make a simple adjustable plate capacitor using PCB elements with transparent tape as the dielectric material. This was used as the timing element for a 555 timer in astable mode. A 555 in this configuration therefore generates a square wave that changes in proportion to how much the plates in the simple capacitor overlap. Turn the plate, and the square wave’s period changes in response. Response time would be fast, and a 555 and some PCB space is certainly cheap materials-wise.

The first prototype gave positive results but had a lot of problems, including noise and possibly a sensitivity to temperature and humidity. The second attempt refined the design and had much better results, with an ESP32 reliably reading 140 discrete positions at a rate of 100 kHz. It seems that there is a tradeoff between resolution and speed; lowering the rate allows more positions to be reliably detected. There are still issues, but ultimately [Jan] feels that high-speed capacitive encoders requiring little more than some PCB real estate and some 555s are probably feasible.

This project is a reminder that FR4 (whether copper-clad, etched, or blank) shows up in clever applications: copper tape and blank FR4 can be used to quickly prototype RF filters, PocketNC built an entire small CNC tool around FR4, and our own [Voja] wrote a full guide on making beautiful enclosures from FR4.

# Printed Parts Make DIY Electric Longboard Possible

Appalled by expensive electric longboards, [Conor Patrick] still wanted one, and wanted it now. So — naturally — he converted an existing board into a sprightly electric version at a fraction of the cost.

[Patrick] is using a capable 380KV Propdrive motor, capable of pushing him up to 30mp/h! A waterproof 120A speed controller and 6000mAh, 22.2V LiPo battery slim enough to fit under the board give the motor the needed juice. He ended up buying the cheapest RF receiver and remote combo to control the board, but it fit the all-important “want electric long board now” criterion.

# Dual Direction Gaming/Dining Room Beam Lights

Sometimes, you just can’t find something you want, and that’s when you break out the tools and get dirty with a bit of DIY. Reddit user [JaredBanyard] wanted a nice beam light for the dining room/gaming room. He ended up building one that shone both downward, on the table, and upward, adding some light to the room.

Warm white LED strip lighting was chosen, and two aluminum channels were glued together to hold them. After wiring the four LED strips together a diffuser was placed over them and then they were wired up and turned on to check the amount of light. With two strips per channel, even with the diffuser, there was plenty.

Each pair of channels were set into the main housing, which is made from Sirari hardwood. Two long outside side pieces make for a great looking final product, and the end pieces are sandwiched between the two outside pieces. After a bit of sanding and an application of matte polyacrylic, transformers were screwed inside and then the channels were placed on top. The circuitry was wired to a Z-Wave dimmer to control the lights remotely.

[JaredBanyard]’s put together a bill of materials and there are plenty of pictures. It’s a great, unique, light for the room, which includes a Duchess gaming table from boardgametables.com. For more lighting articles, check out this 2017 Hackaday Prize entry article on modular rail lighting, or this article about adding intelligence to your lighting solution.

[via Reddit]

# 3D Printed Lamp Even Prints the Nuts and Bolts

The first print to come off a shiny new 3D printer is usually a toy widget of some sort that will forever sit at your desk without purpose. The alternative is a practical project that is custom and personal like this 3D Printed Articulating Lamp. [IgorF2] shares his design for this wall mounted device which was created using Fusion 360.

The complete design consists of eight parts which includes the arms, nuts, and bolts, as well as the wall mount, each of which can be printed individually. These come together to form a structure that can be attached to a wall or your work bench. Though [IgorF2] has provided arm pieces of length 100 mm, 140 mm and 200 mm, you can mix and match to create a much larger project. The files are available for download from Thingiverse for your making pleasure.

We think this can be a great basic structure for someone looking at custom wall mounted projects. The lamp mount can be easily supplemented by a Raspberry Pi and Camera holder if you feel like live streaming your bench. Alternatively, it may be customized to become a motion detecting lamp just for fun. We hope to see some good use come of it in the future.

# 3D Printing on the Subway; Or Anywhere Else!

3D-Printed wearable electronics are on the rise, however our own [Naomi Wu] flipped it around and made a wearable 3D printer which not only is portable but also manufactures on the move!

The project starts with a baby carrier that was locally purchased, and the extra fat was trimmed off leaving behind only the primary harness and square frame. This square frame is left intact to provide stability to the mounted printer as well as some level of comfort to the wearer. [Naomi] then drills a number of new holes in the delta printer in question, of which fortunately the top is made of plastic. Using swivel screws and long screws, the upper part connects with the harness. The receptacle clamp for the upper part is 3D-printed as well, and provides a modular rigid fixture for the machine.

The lower part also uses a 3D-printed triangular base that has a slot for the carrier frame which attaches with the bottom part of the delta using screws. The project is powered via two 3 Ah batteries that are kept in place behind the printer using custom clamps made with PLA. The whole project works on the move, as demonstrated by [Naomi] in the video below.

From dissecting the baby carrier to puncturing holes in a harness using a screwdriver heated by a blow torch, this project has a lot of DIY in it. For those looking for a more productive motorised wearable, check out Adding Haptic Feedback For The Disabled. Continue reading “3D Printing on the Subway; Or Anywhere Else!”

# Network Analysers: The Electrical Kind

Instrumentation has progressed by leaps and bounds in the last few years, however, the fundamental analysis techniques that are the foundation of modern-day equipment remain the same. A network analyzer is an instrument that allows us to characterize RF networks such as filters, mixers, antennas and even new materials for microwave electronics such as ceramic capacitors and resonators in the gigahertz range. In this write-up, I discuss network analyzers in brief and how the DIY movement has helped bring down the cost of such devices. I will also share some existing projects that may help you build your own along with some use cases where a network analyzer may be employed. Let’s dive right in.

# Network Analysis Fundamentals

As a conceptual model, think of light hitting a lens and most of it going through but part of it getting reflected back.

The same applies to an electrical/RF network where the RF energy that is launched into the device may be attenuated a bit, transmitted to an extent and some of it reflected back. This analysis gives us an attenuation coefficient and a reflection coefficient which explains the behavior of the device under test (DUT).

Of course, this may not be enough and we may also require information about the phase relationship between the signals. Such instruments are termed Vector Network Analysers and are helpful in measuring the scattering parameters or S-Parameters of a DUT.

The scattering matrix links the incident waves a1, a2 to the outgoing waves b1, b2 according to the following linear equation: $\begin{bmatrix} b_1 \\ b_2 \end{bmatrix} = \begin{bmatrix} S_{11} & S_{12} \\ S_{21} & S_{22} \end{bmatrix} * \begin{bmatrix} a_1 \\ a_2 \end{bmatrix}$.

The equation shows that the S-parameters are expressed as the matrix S, where and denote the output and input port numbers of the DUT.

This completely characterizes a network for attenuation, reflection as well as insertion loss. S-Parameters are explained more in details in Electromagnetic Field Theory and Transmission Line Theory but suffice to say that these measurements will be used to deduce the properties of the DUT and generate a mathematical model for the same.

# General Architecture

As mentioned previously, a simple network analyzer would be a signal generator connected and a spectrum analyzer combined to work together. The signal generator would be configured to output a signal of a known frequency and the spectrum analyzer would be used to detect the signal at the other end. Then the frequency would be changed to another and the process repeats such that the system sweeps a range of frequencies and the output can be tabulated or plotted on a graph. In order to get reflected power, a microwave component such as a magic-T or directional couplers, however, all of this is usually inbuilt into modern-day VNAs.
Continue reading “Network Analysers: The Electrical Kind”