Litronix 2240 Scientific

		Home New Stuff Author Links Guest book Web-log	Adverts Bric-a-brac Calculators Components Ephemera Events	For Sale Glossary History Hit or Miss Radios Transport	Ultra Valves Wanted Metal Puzzles Clocks

Calculators: Handheld: Litronix 2240 Scientific

		Size (approx):	80mm (max) x 164mm x 13-22mm (w,h,d) Weight 122g excluding batteries
		Power:	4.5V DC using 3 x AA size batteries. It accepts an adapter (4V DC, 300mW) through a socket on the right about two thirds the way up. There is a power down function; after about 30 seconds the display flashes
		Case:	Two piece matt beige plastic case with a thin lower section for the keyboard and fat upper section to accommodate the batteries. A metallic label sits in its own angled recess and is printed black with the brand name and model. The wrap around red display filter is tilted at about 30 degrees and is printed with white text. The keys are short travel clicking type, each in its own recess with aluminium surround. There is a large Example sticker on the rear.
		Display:	9 digit red LED with bubble lens. There is also a discrete red LED for memory indication.
		Features:	Standard four functions, percentages, sign change square root, squares, reciprocal and two function memory. Press button on/off control.
		Age:	c1975
		Manufacturer:	Litronix Inc., Cupertino, California, USA, Assembled in Malaysia. Serial number 104947.
		Comments:	This range of Litronix calculators are very unusual for their flat-as-can-be keyboard design - very stylish. It makes them top heavy to hold in the hand but attractive nevertheless. It has quite an odd display mode but the logic is sound with good recovery.

Components:	1 x cpu: unamed 2307 22K, 28 pin DIL, 0.6" width 1 x IC: LBC 108, 18 pin DIL, 0.3" width 1 x 9 digit red LED unit with bubble lens 2 x transistors 3 x diodes 3 x capacitors 3 x resistors 1 x transformer
Boards:	The whole assembly is one board (Litronix 8300706-8) with all but four components mounted on the top side.
Construction:	Remove the two long screws from the back and the rear section will gently prize off, hinging from the bottom.

Logic comments:	(C/on) is used once to cancel the last number entered and a second press clears the whole calculator.
	Input overflow is suppressed, inputting a ninth digit is ignored
	The change sign function can be used in mid number entry
	The decimal point (mid way up the lower digit) uses one whole display digit but it can reside in any of the nine digits so full eight digit precision is displayed.
	Negative numbers are shown with a minus in the immediate left hand digit travelling into the ninth (far left) digit allowing full eight digit negative numbers
	There is automatic constant on all four functions
	Divide by zero shows "Error" starting in the third digit from the left and is recoverable using (C/on)
	Overflow shows the result flashing and the decimal point surrounded by the lower four segments switched on and is recoverable using (C/on)
	Negative square roots are not allowed and show “Error” and is recoverable using (C/on)
	Memory store is indicated by a discrete LED in the very top left of the display.
	The (RM) key is also a memory cancel key – used by pressing it twice in succession.
	You can store an overflow error in memory without affecting the rest of operation

	This scan of the inside shows how compact the components have to be (there are three diodes and a capacitor on the other side). I do not know who made the ICs as there is so little information on them.