Many users, while enjoying the SpikerBox demo’s we have done, have also expressed excited curiosity that the iPhone can be used as a portable data recorder / oscilloscope. To truly take advantage of your iPhone though, you want your signal to go directly to the line input. Though you can buy one of these cables, in the open-source spirit of Backyard Brains, here is the schematic to build your own. You need: one 4.7 kOhm resistor, one 10 uF capacitor, one 3.5 mm audio three conductor cable you cut in half, and one 3.5 mm audio four conductor cable you cut in half. Bring out your soldering iron, your wire-stripper, and your favorite beverage!
Of course, its only AC coupled, probably +-2V max and 20KHz but still handy for audio techs!
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.