buzzer – Experimental Engineering

Posted on May 23, 2011 by The Engineer — Leave a comment

PSi 150 Power Inverter

This is a small 120W power inverter, intended for small loads such as lights, fans, small TVs & laptop computers.

End cover of the unit, 12v DC input cord at the top, power switch & indicator LEDs at the bottom.

Opposite end of the unit, with the standard 240v AC 50Hz Mains output socket.

Cover removed from the top of the unit. Main power transformer is visible in the centre here, MOSFET bank is under the steel clamp on the left, the aluminium case forms the heatsink.

On the right is a KA3525 switchmode PWM controller & on the left is a LM324N quad Op-Amp IC. The buzzer on the far left is for the low battery warning.

PCB removed from the casing, with the MOSFET bank on the right hand side. Two potentiometers in the centre of the board tweak the frequency of the switcher & the output voltage.

Posted on March 4, 2011February 11, 2011 by The Engineer — Leave a comment

Vivicam 5190

A 5 megapixel digital camera from Vivitar. Visible here is the lens, viewfinder & flash.

Rear of the unit showing the LCD & user control buttons.

Front frame removed showing some of the internals. Shutter assembly & lens in centre, battery compartment at left.

Rear frame removede, showing the LCD module & tactile switches.

LCD module removed from the PCB

Flash PCB removed. Transformer is fed with the 4.5v from the 3 AA cells & steps it up to ~300v DC for the flash capacitor. A pulse transformer energizes an electrode next to the Xenon flash tube with ~5kV to ionize the gas.

Main PCB removed. Internal flash ROM & RAM IC visible above the SD card socket. USB connector is at the top right, next to the piezo buzzer.

Main processor on reverse side of the PCB.

Closeup of the CMOS image sensor with the lens assembly removed.

Posted on January 14, 2011 by The Engineer — Leave a comment

Uniden Stalker Radar Detector

An early speed radar detector from the early 90’s. Pictures showing the front of the unit with the option buttons.

Bottom of the unit showing label. Unlike the newer plastic detectors, the whole casing of this unit is cast aluminium.
Model Uniden Stalker RD-6000W.

PCB removed from the casing. Volume/power control on the left. Option tactile switches on the edge of the PCB, with the indicator LEDs. Power input jack on the right hand side of the PCB. Large aluminium can is the detector assembly, containing the detector diodes. Waveguide horn is at the top.

Shot down the waveguide, showing the detector diodes at the end.

Indicators on the front of the unit, X, K & Ka band detection LEDs on the left, Power & detection level (1-4) LEDs in centre. City (C) (Audio (A) & Mute (M) LEDs on the right.

Bottom of the PCB, showing detection logic. Piezo buzzer top left.

Custom Uniden CPU. Marking UC1465.

Posted on August 25, 2010 by The Engineer — Leave a comment

Ericsson GA628

Here is a phone from the mid 90s, the Ericsson GA628. Here visible is the front of the unit with keypad, & single line monochrome LCD for number display.

Here the battery is removed from the phone, showing the SIM card socket. At the top under the antenna stub is the socket for an external antenna.

Here the front is removed from the phone, PCB on left, rear of keypad on right. Microphone is at bottom of keypad, with speaker at the top. Top right of the PCB is the ringer buzzer, left is shield for RF amplifier.

Here is the back of the main PCB, RF sections on left & centre. Processing & memory on right.

This phone had a Ni-Mh battery, before Li-Ion batteries were introduced.

The LCD from the front of the phone is shown here. A simple dot matrix single line unit.