Adding A Backlight To A Cheap Multimeter

We don’t all need super high quality electronic testing gear. Sometimes second-hand or inexpensive equipment is accurate enough to get the job done. Though it can be a bit annoying to miss out on some of those “luxury” features. [Ekriirke] had this problem with his cheap multimeter. He wished the LCD screen had a backlight for easier visibility, so rather than upgrade to a more expensive unit he just added one himself.

After opening up the multimeter [Ekriirke] found that it ran on a single 12V battery. He realized that the simplest thing to do would be to wire up four white LEDs in series. The four LEDs were arranged within the case off to each side of the LCD, one in each corner. The leads were bent at 90 degree angles and soldered together “dead bug” style. Thin strips of copper foil tape were attached to the PCB in such a way that the anode and cathode from the LEDs would make contact when the case was closed back up.

The tape wraps around to the other side of the PCB where there was more room for the next piece of the circuit. A capacitor, resistor, and transistor are used in conjunction with a momentary switch. This circuit allows [Ekriirke] to turn on the light for about ten seconds by pressing the button one time. The circuit also runs through the meter’s dial switch, preventing the LEDs from being turned on while the meter itself is turned off.

[via Reddit]

More GPIOs For The ESP8266

The ESP8266 is an incredible piece of hardware; it’s a WiFi module controllable over a serial port, it’s five freaking dollars, and if that’s not enough, there’s a microcontroller on board. Until there’s a new radio standard, this is the Internet Of Things module.

The most common version of the ESP, the -01 version, only has a 2×4 row of pins for serial, power, configuration, and two lines of GPIO. It’s a shame that module only has two GPIOs, but if you’re good enough with a soldering iron you can get a few more. It took a lot of careful soldering, but [Hugatry] managed to break out two more GPIOs on this tiny module.

According to [Hugatry] a lot of patience to solder those wires onto those tiny pads, but after finishing this little proof of concept he discovered a Russian hacker managed to tap into four extra GPIOs on the ESP8266-01 module (Google Translatrix).

As a proof of concept, it’s great, but there’s more than one ESP module out there. If you’re looking for a cheap WiFi module, check out the ESP-03, -04, or -07; they have nice castellated pins that are exceptionally easy to solder to.

Video below.
Continue reading “More GPIOs For The ESP8266”

Open Source, DIY Soldering Robot

After [Brian] starting selling his own Raspberry Pi expansion boards, he found himself with a need for a robot that could solder 40-pin headers for him. He first did what most people might do by looking up pre-built solutions. Unfortunately everything he found was either too slow, too big, or cost as much as a new car. That’s when he decided to just build his own soldering robot.

The robot looks similar to many 3D printer designs we’ve seen in the past, with several adjustments. The PCBs get mounted to a flat piece of aluminum dubbed the “PCB caddy”. The PCBs are mounted with custom-made pins that thread into the caddy. Once the PCBs are in place, they are clamped down with another small piece of aluminum. A computer slowly moves the caddy in one direction, moving the header’s pins along the path of the soldering irons one row at a time.

The machine has two soldering irons attached, allowing for two pins to be soldered simultaneously. The irons are retracted as the PCB caddy slides into place. They irons are then lowered onto the pins to apply heat. Two extruders then push the perfect amount of solder onto each pin. The solder melts upon contact with the hot pins, just as it would when soldered by hand.

The system was originally designed to be run on a Windows 8.1 tablet computer, but [Brian] found that the system’s internal battery would not charge while also acting like a USB host. Instead, they are running the Windows WPF application on full PC. All of the software and CAD files can be found on [Brian’s] github page. Also be sure to check out the demo video below. Continue reading “Open Source, DIY Soldering Robot”

Great Scott! A Flux Capacitor Notification Light

If you are into your social media, then you probably like to stay updated with your notifications. [Gamaral] feels this way but he wasn’t happy with the standard way of checking the website or waiting for his phone to alert him. He wanted something a little more flashy. Something like a flux capacitor notification light. This device won’t send his messages back in time, but it does look cool.

He started with an off-the-shelf flux capacitor USB charger. Normally this device just looks cool when charging your USB devices. [Gamaral] wanted to give himself more control of it. He started by opening up the case and replacing a single surface mount resistor. The replacement component is actually a 3.3V regulator that happens to be a similar form factor as the original resistor. This regulator can now provide steady power to the device itself, as well as a ESP8266 module.

The ESP8266 module has built-in WiFi capabilities for a low price. The board itself is also quite small, making it suitable for this project. [Gamaral] used just two GPIO pins. The first one toggles the flux circuit on and off, and the second keeps track of the current state of the circuit. To actually trigger the change, [gamaral] just connects to the module via TCP and issues a “TIME CIRCUIT ON/OFF” command. The simplicity makes the unit more versatile because an application running on a PC can actually track various social media and flash the unit accordingly.

Animated LED Valentine Heart

With only a week left until Valentine’s day, [Henry] needed to think on his feet. He wanted to build something for his girlfriend but with limited time, he needed to work with what he had available. After scrounging up some parts and a bit of CAD work, he ended up with a nice animated LED Valentine heart.

[Henry] had a bunch of WS2812 LEDs left over from an older project. These surface mount LED’s are very cool. They come in a small form factor and include red, green, and blue LEDs all in a single package. On top of that, they have a built-in control circuit which makes each LED individually addressable. It’s similar to the LED strips we’ve seen in the past, only now the control circuit is built right into the LED.

Starting with the LEDs, [Henry] decided to build a large animated heart. Being a stickler for details, he worked out the perfect LED placement by beginning his design with three concentric heart shapes. The hearts were plotted in Excel and were then scaled until he ended up with something he liked. This final design showed where to place each LED.

The next step was to design the PCB in Altium Designer. [Henry’s] design is two-sided with large copper planes on either side. He opted to make good use of the extra copper surface by etching a custom design into the back with his girlfriend’s name. He included a space for the ATMega48 chip which would be running the animations. Finally, he sent the design off to a fab house and managed to get it back 48 hours later.

After soldering all of the components in place, [Henry] programmed up a few animations for the LEDs. He also built a custom frame to house the PCB. The frame includes a white screen that diffuses and softens the light from the LEDs. The final product looks great and is sure to win any geek’s heart. Continue reading “Animated LED Valentine Heart”

Annoy Your Enemies with the Hassler Circuit

[Craig] recently built himself a version of the “hassler” circuit as a sort of homage to Bob Widlar. If you haven’t heard of Bob Widlar, he was a key person involved in making analog IC’s a reality. We’ve actually covered the topic in-depth in the past. The hassler circuit is a simple but ingenious office prank. The idea is that the circuit emits a very high frequency tone, but only when the noise level in the room reaches a certain threshold. If your coworkers become too noisy, they will suddenly notice a ringing in their ears. When they stop talking to identify the source, the noise goes away. The desired result is to get your coworkers to shut the hell up.

[Craig] couldn’t find any published schematics for the original circuit, but he managed to build his own version with discrete components and IC’s. Sound first enters the circuit via a small electret microphone. The signal is then amplified, half-wave rectified, and run through a low pass filter. The gain from the microphone is configurable via a trim pot. A capacitor converts the output into a flat DC voltage.

The signal then gets passed to a relaxation oscillator circuit. This circuit creates a signal whose output duty cycle is dependent on the input voltage. The higher the input voltage, the longer the duty cycle, and the lower the frequency. The resulting signal is sent to a small speaker for output. The speaker is also controlled by a Schmitt trigger. This prevents the speaker from being powered until the voltage reaches a certain threshold, thus saving energy. The whole circuit is soldered together dead bug style and mounted to a copper clad board.

When the room is quiet, the input voltage is low. The output frequency is high enough that it is out of the range of human hearing. As the room slowly gets louder, the voltage increases and the output frequency lowers. Eventually it reaches the outer limits of human hearing and people in the room take notice. The video below walks step by step through the circuit. Continue reading “Annoy Your Enemies with the Hassler Circuit”

Get Better at Mortal Kombat by Hacking Your PS3 Controller

Fighting games like Mortal Kombat provide you with a variety of different available moves. These include kicks, punches, grabs, etc. They also normally include various combination moves you can perform. These combo moves require you to press the proper buttons in the correct order and also require you to time the presses correctly. [Egzola] realized that he could just hack his controller to simulate the button presses for him. This bypasses the learning curve and allows him to perform more complicated combinations with just the press of a single button.

[Egzola] started by taking apart his Playstation 3 controller. There were two PCB’s inside connected by a ribbon cable. Luckily, each individual pad for this cable was labeled with the corresponding controller button. This made it extremely simple to hack the controller. [Egzola] soldered his own wires to each of these pads. Each wire is a different color. The wires then go to two different connectors to make them easier to hook up to a bread board.

Each wire is then broken out on the breadboard. The signal from each button is run through a 4n25 optoisolator. From there the signal makes its way back to various Arduino pins. The 4n25 chips keeps the controller circuit isolated from the Arduino’s electrical circuit. The Arduino also has two push buttons connected to it. These buttons are mounted to the PS3 controller.

Now when [Egzola] presses one of the buttons, the Arduino senses the button press and simulates pressing the various controller buttons in a pre-programmed order. The result is a devastating combination move that would normally require practice and repetition to remember. You might say that [Egzola] could have spent his time just learning the moves, but that wasn’t really the point was it? Check out the video below for a demonstration. Continue reading “Get Better at Mortal Kombat by Hacking Your PS3 Controller”