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I recently bought this LCD screen for a project: https://www.jaycar.com.au/4-digit-field-effect-lcd/p/ZD1886

This LCD screen is just for testing at the moment, the final project will use these (I Hope): http://au.element14.com/lumex/lcd-s2x1c50tr/no-of-digits-alpha-2-5/dp/1703044

I read the specs and both say that they run at about 3V (The second one I believe says 3-5V).

My project is running off of 6V (4 x AA), and I read online that to drive something that requires 3V from a 6V supply, is to put another wire between two of the pairs of batteries:

+6V +3V GND
AA AA | AA AA

(I hope the above makes sense).

So back to my initial questions

1) I did a few tests of hooking 3V up to the ground and one of the pins for a decimal place (as I won't be using those so it doesn't matter to me if those parts die), and I noticed that upon disconnecting the LCD section remained in its darkened/visible state for about half a second, and so I was curious and hooked 6V up to another decimal point (again on a second I know I won't need), and it became visible, and still worked afterwards, but it remained darker for about 2 seconds.

Is this caused by the higher voltage actually damaging the insides or what's the go here? I would have assumed if I put double the recommended voltage, it would have stuffed that segment, or the whole LCD screen.

2) As per the above question the segments remain on for about half a second, while my project won't require quick timing, I want to know if there is an AMP limit (similar to LEDs) and I just can't notice it in the specs, or will I be safe to hook the LCD straight to the supply?

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Segment displays with a multiplex such as 4:1 or 1:1 use AC signal, in fact DC signal can destroy the LCD in short time. Segments can operate as low as 2.7 volts and as high as 5V.

Here is an article about the damage DC offset voltage can do to a display and now to avoid it.

Note: I am a design engineer at Focus LCDs and am supplying the link as a supporting document.

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All sorted, I discovered LCD screens Require AC power, so I'll be replacing my CMOS 4511 chips with CMOS 4056 chips which support this ability.

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  • \$\begingroup\$ You can mark this as your accepted answer. You can upvote other answers if they were helpful. \$\endgroup\$
    – Transistor
    Mar 6 '18 at 22:27

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