quartz – Experimental Engineering

Posted on December 15, 2010 by The Engineer — Leave a comment

Logitech Cordless Ball Mouse

This is an old legacy wireless mouse from Logitech. This uses a ball rather than optical technology.

Bottom of the mouse, showing the battery cover & the mouse ball.

Top removed from the mouse, showing the PCB inside. The smaller PCB on the left supports the microswitches for the buttons & mouse wheel.

Closeup of small PCB showing the microswitches & the IR LED & phototransistor pair for the mouse wheel encoder.

View of main PCB, with interface IC lower right. Pair of quartz crystals provide clocking for the transmitter & internal µC.
Battery contacts are on lower left of the PCB. At the top are the IR pairs for the X & Y axis of the mouse ball.

Closeup of the pairs of IR LEDs & phototransistors that make up the encoders for X/Y movement of the mouse, together with the slotted wheels in the mouse base that rotate with the ball. Steel wire around the smaller PCB is the antenna.

Posted on December 10, 2010 by The Engineer — Leave a comment

Belkin PCMCIA Wi-Fi Card

Here is an old Belkin Wireless G network card. This is a PCMCIA version.

Here is the bottom of the device, with all the details.

Plastic antenna cover removed, showing the pair of 2.4GHz etched antennae. There is a pair of LEDs on the upper left of the PCB showing activity & link status.

Overall view of the PCB, antennae on the left, RF chipset in centre, WiFi controller IC on right, and PCMCIA socket on far right. Can below wireless controller is a quartz crystal for the clock.

Closeup of the chipset, a Ralink RT2560F wireless controller on the right & a RT2525L transceiver on the left.

Posted on December 6, 2010 by The Engineer — Leave a comment

Southwestern Bell Freedom Phone

This is an old cordless landline phone, with dead handset batteries.

Here’s the handset with the back removed. Shown is the radio TX/RX board, underneath is the keyboard PCB with the speaker & mic. All the FM radio tuning coils are visible & a LT450GW electromechanical filter.

Radio PCB removed from the housing showing the main CPU controlling the unit, a Motorola MC13109FB.

The keypad PCB, with also holds the microphone & speaker.

Bottom of the keypad board, which holds a LSC526534DW 8-Bit µC & a AT93C46R serial EEPROM for phone number storage.

Here’s the base unit with it’s top cover removed. Black square object on far right of image is the microphone for intercom use, power supply section is top left, phone interface bottom left, FM radio is centre. Battery snap for power backup is bottom right.

PSU section of the board on the left here, 9v AC input socket at the bottom, with bridge rectifier diodes & main filter capacitor above. Two green transformers on the right are for audio impedance matching. Another LT450GW filter is visible at the top, part of the base unit FM transceiver.

Another 8-bit µC, this time a LSC526535P, paired with another AT93C46 EEPROM. Blue blob is 3.58MHz crystal resonator for the MCU clock. The SEC IC is a KS58015 4-bit binary to DTMF dialer IC. This is controlled by the µC.

Underside of the base unit Main PCB, showing the matching MC13109FB IC for the radio functions.