The Ben Heck Show

Ben Heck's Smart Switching Headphones (6x46)

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Ben takes an off-the shelf baby monitor and creates adaptive headphones that switch between a music device such as an iPod or phone and noise from a secondary input such as a crying baby. He does so using integrated circuits, discrete components built into the case. Bit by the bug? Visit: http://bit.ly/2gOSzx6 Ben takes apart a baby monitor to see if he can build the circuitry inside of it. Inside the baby monitor is a radio module, a glop top integrated circuit that runs everything, power regulator, crystal that runs the circuitry, some caps, an antenna, and an IC that might be some sort of memory or identification chip. It might be possible to use the battery that powers the baby monitor to also power the switching circuit. The speaker could also be removed entirely and turned into a headphone jack. In order to see if the amplification going to the speaker needs to be knocked down a bit to prevent hearing damage, Ben hooks it up to a battery to see how much current it draws. It’s drawing about 50 milliamps which isn’t too bad so Ben continues testing with Felix simulating baby sounds. For this project Ben uses the ADG 436 integrated circuit, a two channel switching circuit, so they can use logic on or off to switch from one channel to another. The outputs are hooked up to headphones and a pair of Nintendo Game Boys that act as inputs. There are pull down resistors so that both of the inputs are set to low. Ben looks for a way to combine the switching circuit with the baby monitor. The switching circuit has been tested to work down to about 1.8 volts. He then probes around to see where all the voltages are so that he can power the switching circuit. He finds a boost regulator used to boost the lower level of the batteries up to a stable level of 3.2 volts for device operation. He also finds that the system voltage can be found on many test pads around the unit as well as the positive terminals of several of the electrolytic capacitors. He then