A Simple Laser Harp MIDI Instrument

June 19, 2024 by Dave Rowntree 5 Comments

Craig Lindley is a technical author and a prolific maker of things. This simple project was his first attempt to create a laser harp MIDI device. While on vacation, Craig saw a laser harp with only three strings and decided to improve upon it by expanding it to twelve strings. The principle of operation is straightforward: twelve cheap diode laser modules aim a beam towards an LDR, which changes resistance if the light level changes when the beam is interrupted.

The controller is a simple piece of perf board, with a Wemos D1 mini ESP32 module flanked by some passives, a barrel socket for power, and the usual DIN connector for connecting the MIDI instrument. Using the ESP32 is a smart choice, removing all the need for configuration and user indication from the physical domain and pushing it onto a rarely-needed webpage. After a false start, attempting to use a triangular frame arrangement, [Craig] settled upon a simple linear arrangement of beams held within a laser-cut wooden box frame. Since these laser modules are quite small, some aluminium rod was machined to make some simple housings to push them into, making them easier to mount in the frame and keeping them nicely aligned with their corresponding LDR.

Sadly, the magnetic attachment method [Craig] used to keep the LDRs in place and aligned with the laser didn’t work as expected, so it was necessary to reach for the hot glue. We’ve all done that!

An interesting addition was using an M5 stack Unit-Synth module for those times when a proper MIDI synthesiser was unavailable. Making this luggable was smart, as people are always fascinated with laser harps. That simple internal synth makes travelling to shows and events a little easier.

Laser harps are nothing new here; we have covered plenty over the years. Like this nice build, which is more a piece of art than an instrument, one which looks just like a real harp and sounds like one, too, due to the use of the Karplus-Strong algorithm to mimic string vibrations.

Protoboard Z80 Computer Teaches The Basics

May 11, 2024 by Tom Nardi 16 Comments

As curious people, we’re all incredibly fortunate to live in an age where information can so easily be obtained. If you want to learn how something works, from a cotton gin to an RBMK reactor, you’re just a few keystrokes away from articles, diagrams, and videos on the subject. But as helpful as all of that information can be, we also know that there’s no substitute for hands-on experience.

While we can’t recommend you try building a miniature graphite-moderated nuclear reactor, there’s plenty of other devices that you can study by constructing your own functioning model. For example, when [Jorisclayton] wanted to really know what was going on inside a computer, they decided to go back to basics and build their own Z80 machine. To maximize the experience, they skipped any of the existing kit designs and instead wired the whole thing up by hand across a few perfboards.

The main board contains a 4 MHz Z80 processor, paired with 32K ROM and 64K RAM. Here you’ll also find the clock generator, I/O decoder, serial port, voltage regulator, and a trio of expansion slots that use a long strip of 2.54 mm pin headers as the interface. In the first expansion slot you’ve got a primordial “graphics card” based around the TMS9918 video display controller (VDC) and 16K of additional RAM. The second expansion card has a CompactFlash reader and an LED array mapped to I/O address 0x00h so it can be used for various notifications.

[Jorisclayton] says the final expansion board is still being worked on, but the idea is for it to handle user input through a PS/2 keyboard connector, as well as provide ports for a pair of Super Nintendo (or compatible) controllers. Everything is held together with a minimalist 3D printed frame to show off all that careful soldering.

Obviously there’s no PCB design files to share for this one, but [Jorisclayton] has posted a schematic for wiring everything up if you’re looking for resources to build your own Z80 computer. Sure the chips themselves might no longer be in production, but that doesn’t mean this venerable CPU is going anywhere just yet.

Scrambling Pocket Calculators Made Easy With EMP Box V2

June 20, 2022 by Donald Papp 47 Comments

[Rostislav Persion] has for some time been interested in making small, portable EMP devices capable of interfering with nearby electronics. In these EMP devices, high voltage is used to create a portable spark gap generator, whose operation in turn creates electromagnetic pulses capable of resetting or scrambling nearby electronics such as pocket calculators.

Bridging adjacent holes narrows the spark gap, resulting in more frequent pulses.

His original EMP box designs relied on spark gaps constructed from metal screws threaded into a clear plastic insulator, but this newest design ditches fussy screw adjustments and relies on perfboard. By cutting out a single row of plated perfboard holes and soldering the high voltage terminals to each end, the empty holes in between form the essential parts of a spark gap.

It’s even adjustable: one simply bridges adjacent holes with solder to effectively decrease the gap. As for generating the high voltage itself, a DC voltage multiplier from Amazon takes care of that. Watch the device reset some calculators in the short video below.

Looking for high-voltage experiments that aren’t so sketchy? Get yourself a Van de Graff generator, some metal balls, and a little bit of oil, and make some art.

Continue reading “Scrambling Pocket Calculators Made Easy With EMP Box V2” →

Brilliant Brick Prototyping

February 3, 2021 by Kerry Scharfglass 24 Comments

Have a rusty collection of protoboards wired together that would benefit from mechanical support? Working on putting together a robot and need to attach PCBAs without drilling holes, zipping a cable tie, or globing hot glue? Add some stud holes with [James Munns]’ Brick Mount! This isn’t the first time we’ve seen an interface between everyone’s favorite Nordic building system and circuitboards, but this implementation has the elegance we’ve come to expect from [James]’ software work.

The project repository contains two things: a KiCad library with components for holes in standard patterns and sizes (1×1, 1×2, etc) and a series of protoboards made with those hole components. The protoboards feature a couple common elements; QUIIC connectors for easy chaining between them and holes in the middle or edges for easy mounting on studs. Some are intended to be carriers for Feather-format PCBAs (very convenient!) and others are primarily undifferentiated prototyping space. Of particular note is the “medium” Feather breakout seen to the left, which incorporates clever cutouts to make it easy to wires down under the board so it can be mounted flush against another board.

The thesis here is that getting custom PCBs fabricated is easier and less expensive than ever before. So easy and inexpensive that fabricating customized protoboard to use in one-off projects is cost-efficient enough to be worthwhile. Waste concerns aside this does seem like a great way to level up those temporary projects which find a more permanent home.

Don’t Scrape Magnet Wire, Do This Instead

March 9, 2020 by Donald Papp 111 Comments

[Tom] doesn’t much like breadboarding. He prefers to wire up prototypes with perfboard and solder point-to-point with enameled magnet wire. That may sound troublesome to some of you, but [Tom] has come up with a few tips to make prototyping with perfboard and magnet wire easier and more effective, and the biggest tip is about how to manage stripping all that magnet wire.

Push the tip of the magnet wire a small distance into the molten solder and hold it there for a few moments. The solder will bubble away the enamel and tin the copper underneath in the process.

Magnet wire is a thin, solid-core conductor that has a clear coating of enamel. This enamel acts as an electrical insulator. The usual way to strip away the enamel and reveal the shiny copper underneath is to scrape it off, but that would get tiresome when working with a lot of connections. [Tom] prefers to “boil it away” with a blob of molten solder on an iron’s tip.

Begin by melting a small amount of solder on the iron, then push the tip of the magnet wire a small distance into the molten solder and hold it there for a few moments. The enamel will bubble away and the solder will tin the copper underneath in the process. The trick is to use fresh solder, and to clean the tip in between applications. You can see him demonstrate this around the 1:00 mark in the video embedded below.

Once the tip of the magnet wire is tinned, it can be soldered as needed. Magnet wire bends well and holds its shape nicely, so routing it and cutting to size isn’t too difficult. [Tom] also suggests a good hands-free PCB holder, and points out that 0603 sized SMT resistors fit nicely between a perfboard’s 0.1″ pads.

Perfboard (and veroboard) have been standbys of prototyping for a long time, but there are still attempts at improving them, usually by allowing one to combine through-hole and surface-mount devices on the same board, but you can see [Tom] demonstrate using magnet wire on plain old perfboard in the video below.

Continue reading “Don’t Scrape Magnet Wire, Do This Instead” →

High Voltage Measurement Is Shockingly Safe

November 17, 2018 by Bryan Cockfield 9 Comments

With the right equipment and training, it’s possible to safely work on energized power lines in the 500 kV range with bare hands. Most of us, though, don’t have the right equipment or training, and should take great care when working with any appreciable amount of voltage. If you want to safely measure even the voltages of the wiring in your house there’s still substantial danger, and you’ll want to take some precautions like using isolated amplifiers.

While there are other safe methods for measuring line voltage or protecting your oscilloscope, [Jason]’s isolated amplifier method uses high voltage capacitors to achieve isolation. The input is then digitized, sent across the capacitors, and then converted back to an analog signal on the other side. This project makes use of a chip from TI to provide the isolation, and [Jason] was able to build it on a perfboard while making many design considerations to ensure it’s as safe as possible, like encasing high voltage sections in epoxy and properly fusing the circuit.

[Jason] also discusses the limitations of this method of isolation on his site, and goes into a lot of technical details about the circuit as well. It probably wouldn’t get a UL certification, but the circuit performs well and even caught a local voltage sag while he was measuring the local power grid. If this method doesn’t meet all of your isolation needs, though, there are a lot of other ways to go about solving the problem.

Improved Perfboard For Surface Mount Parts

January 9, 2018 by Brian Benchoff 26 Comments

Look through the last two decades of electronics project built on perfboard, and you’ll notice a trend. Perfboard is designed for through-hole parts, but ever more frequently, the parts we need are only available as surface mount devices. What does this mean for the future of all those protoboard, veroboard, and tagboard designs? It’s not good, but fortunately, there may be an answer. It’s perfboard designed for mounting SOICs, SOTs, and other surface mount devices.

Perfboard is an extremely simple concept. Most through-hole electronic components are built around 0.1″ or 2.54 mm spacing between pins. Yes, there are exceptions, but you can always bend the middle pin of a transistor and put it in a hole. SMT devices are different. You can’t really bend the pins, and the pin pitch is too small for the 0.1″ holes in traditional perfboard.

[electronic_eel] is changing that game up with his own design for perfboard. This perfboard has the traditional 0.1″ holes, but there are SMD pads sprinkled about between these holes. The result is being able to solder SOIC, SOT23-6, SOT23 and SOT363 devices directly to a board alongside 0603 and 0805 devices. Connect everything with a few beads of solder and you have a functional circuit made out of surface mount devices on something that’s still compatible with the old protoboard designs.

This isn’t the first time we’ve seen a new type of protoboard make it into production. A few years ago, Perf+, a bizarre ‘bus-based’ protoboard solution came onto the scene, although that wasn’t really designed for SMD parts. While [electronic_eel] doesn’t have any plans to sell his protoboard, the files are available, and you can easily design your own small piece of perfboard.