Stereo Audio IO Landing Pad for Olimex SAM7-H256: Assembled

CNC milled dual channel audio input/output board for the Olimex SAM7-h256 and SAM7-H64 header boards. Input is through an AC-coupled preamp with a single-pole bandpass input with attenuation into a rail to rail opamp in voltage follower configuration. -3db response was simulated at 2Hz-30KHz. A though port is provided to use the device an an audio monitor. Output is a pair of SAM7 PWM through a 4-pole active low-pass filter. Configuration is butterworth salen-key at 10KHz. High end audio hurts. The LED VU display is unbuffered, running at about 2.4 mA, about half a mA beyond spec for 4 of those pins. Headers are provided for asynchronous RS232 comm and external 3.3V supply. Currently it gets power from the USB.

• dts7had01_schema.png
• dts7had01_parts.txt

Posted by rmrubin Posted in: Electronics Comments Off February 2008

Jabra BT125 Bluetooth Headset Teardown

Two very small torx screws, edge snaps, some plastic hooks at the end with mating feature on the opposite chassis piece. Speaker is insulated from the main chassis by a rubber-like pad. The mic is built into a pod made of the same rubbery material, which when mounted fits flush with the outer chassis. Torx screws came out with a clipped xacto blade tip.

Going to swap the blue 0603 LED for a red one. Maybe amber. Will possibly swap the 0402 resistor with a larger one. Try to kill the sniper beacon blink effect. Alternative is a thick film or thin paper light filter behind the translucent white button.

The grid is .250″.

Posted by rmrubin Posted in: Electronics Comments Off February 2008