![Front](http://www.experimental-engineering.co.uk/wp-content/uploads/2013/02/2013-02-13-17.46.49-300x169.jpg)
This is a late 90’s business timeclock, used for maintaining records of staff working times, by printing the time when used on a sheet of card.
![Front Internal](http://www.experimental-engineering.co.uk/wp-content/uploads/2013/02/2013-02-13-17.46.32-169x300.jpg)
Here is the top cover removed, which is normally locked in place to stop tampering. The unit is programmed with the 3 buttons & the row of DIP switches along the top edge.
![Instructions](http://www.experimental-engineering.co.uk/wp-content/uploads/2013/02/2013-02-13-17.47.01-300x169.jpg)
Closeup of the settings panel, with all the various DIP switch options.
![CPU & Display](http://www.experimental-engineering.co.uk/wp-content/uploads/2013/02/2013-02-13-17.47.17-300x169.jpg)
Cover plate removed from the top, showing the LCD & CPU board, the backup battery normally fits behind this. The CPU is a 4-bit microcontroller from NEC, with built in LCD driver.
![PSU & Drivers](http://www.experimental-engineering.co.uk/wp-content/uploads/2013/02/2013-02-13-17.52.04-300x169.jpg)
Power Supply & prinhead drivers. This board is fitted with several NPN Darlington transistor arrays for driving the dox matrix printhead.
![Printhead](http://www.experimental-engineering.co.uk/wp-content/uploads/2013/02/2013-02-13-17.53.28-300x169.jpg)
Printhead assembly itself. The print ribbon fits over the top of the head & over the pins at the bottom. The drive hammers & solenoids are housed in the circular top of the unit.
![Printhead Bottom](http://www.experimental-engineering.co.uk/wp-content/uploads/2013/02/2013-02-13-17.53.52-300x169.jpg)
Bottom of the print head showing the row of impact pins used to create the printout.
Bottom of the solenoid assembly with the ribbon cable for power. There are 9 solenoids, to operate the 9 pins in the head.
![Return Spring](http://www.experimental-engineering.co.uk/wp-content/uploads/2013/02/2013-02-13-18.00.56-300x169.jpg)
Top layer of the printhead assembly, showing the leaf spring used to hold the hammers in the correct positions.
![Hammers](http://www.experimental-engineering.co.uk/wp-content/uploads/2013/02/2013-02-13-18.01.16-169x300.jpg)
Hammer assembly. The fingers on the ends of the arms push on the pins to strike through the ribbon onto the card.
![Solenoids](http://www.experimental-engineering.co.uk/wp-content/uploads/2013/02/2013-02-13-18.02.39-300x169.jpg)
The ring of solenoids at the centre of the assembly. These are driven with 3A darlington power arrays on the PSU board.
![Gearbox Internals](http://www.experimental-engineering.co.uk/wp-content/uploads/2013/02/2013-02-13-18.05.07-300x169.jpg)
There is only a single drive motor in the entire unit, that both clamps the card for printing & moves the printhead laterally across the card. Through a rack & pinion this also advances the ribbon with each print.