Aero Navigation Lights

Chris73 wrote: Woah there, off topic alert :ohmy:
Better lock the thread

With Loctite?
Ps, this is a Darlington Pear

Okay Okay! I've been hijacked so you have asked for it. I thought it may have been of interest to some of you as this circuitry/module is far superior to the crap HK and others led systems. Read on if you wish.

The Darlington transistor (often called a Darlington pair) is a compound structure consisting of two bipolar transistors (either integrated or separated devices) connected in such a way that the current amplified by the first transistor is amplified further by the second one. This configuration gives a much higher current gain than each transistor taken separately and, in the case of integrated devices, can take less space than two individual transistors because they can use a shared collector. Integrated Darlington pairs come packaged singly in transistor-like packages or as an array of devices (usually eight) in an integrated circuit.

The Darlington configuration was invented by Bell Laboratories engineer Sidney Darlington in 1953. He patented the invention of having two or three transistors on a single chip sharing a collector. A similar configuration but with transistors of opposite type (one NPN and one PNP) is the Sziklai pair, sometimes called the "complementary Darlington".

The Array is so called because the pairs of transistors are embedded into a chip therefore eliminating the need for rows and rows of transistors.

Hmmm back on track, your diagram shows a very unusual depiction of the circuitry of a darlington array Phil. The circuits shown imply a logical NOT gate with the output voltage pegged to no more than the forward voltage of a diode (i.e typically 0.6v).
I.e. if you drove the input of a gate to say 6V, the output will be ~0v; and if you drive the input to 0V the output will be no more than ~0.6V (or less if germanium).
Are you sure that is the right chip?

Actually I take back the bit about the pegged output. The diodes actually point at what is labelled in your depiction as "Common" but is actually "VCC" therefore all they do is protect the NOT gate from overvoltage from the driven circuitry.

Definitely Logical Captain. The ULN2003 is a high voltage, high current darlington array containing seven open collector darlington pairs with common emitters. Each channel rated at 500 mA and can withstand peak currents of 600 mA. Suppression diodes are included for inductive load driving (ie; stepper motors) and the inputs are pinned opposite the outputs to simplify board layout.

This Darlington switches to ground on it's output pins when triggered therefore completing the circuit. The positive of the load is directly connected to the battery. Pin 9 is used when a motor or inductive load is used.

All this for £0.33p Better than 14 transistors and diodes. :lol: