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Ben continues rebuilding the flipper mecs to get an idea how they can work with the smaller solenoids while Felix continues working on the Teensy 3.1, a popular microcontroller based on Freescale system on a chip. Felix is going to try and get the DAC working, the digital to analog converter, so they can get it to play music and sound effects.
Felix takes a Teensy 3.6 and puts it on a board attached to a smaller board containing the MOSFETs and buttons to trigger the solenoids. He mounts the Teensy 3.6 onto a larger board. He connects an audio jack to the DAC on the Teensy. There are also two outputs on the board for the solenoids. Felix adds two more MOSFETs to give it a total of four solenoids, headers for three buttons, and a header for the servo. The Teensy is a 3.3 V logic with a 3 V regulator on it. On the board a battery goes into a regulator and the 5 Volts is going to the Teensy. From the Teensy he has 3 Volts going to the little board he glued on for the logic. The 16 Volts in the battery when fully charged comes into the regulator which knocks it down to 5 V. A switch separates the 5 V from the Teensy for programming purposes. Felix goes to work on getting the DAC working.
Ben uses bandsaws, lasers, and 3D printers to create a mock-up while Felix is works on the circuits. He uses longer flippers than before to get more motion out of smaller solenoids. Satisfied with how the test flipper is moving the ball, he builds the other flipper and a case at the right angle so he can then hook it up to what Felix is making.
Felix is having trouble with the SD card reading while getting the DAC working so Ben gives it a look. The mini pinball is intended to be a DIY kit so they're making sure it's Arduino programmable with the Teensy 3.6. Felix puts some potentiometers on the board so they can change the duty cycle, to PWM it. As far as PWM goes, they're going to want a full burst when you push the button, so it has the power to go up and once it's up they'll start by counting to 1/10th of a second before switching to a PWM. PWM will allow them to hold the flipper up without keeping it fully on, which could damage the coil. Ben refines the code that Felix worked on. They'll hard-code these values in for the final version, potentiometers allow them to test quickly. They blink an LED at full kernel speed and divide by 2 to determine the actual frequency with interpretation and wiring. They pulse the LED, look at it in the oscilloscope, and use that to divide up the actual values they need.
Working in Autodesk Fusion 360, Ben goes to work on redesigning the flipper. He designs these flippers with a 15 degree slope (instead of the standard 30) to make the game easier. Felix continues troubleshooting audio on the Teensy 3.6. The newest Teensy uses the full 4 bits of the SD card, whereas older libraries only used 1 bit SPI mode.