I can't believe I'm asking this, but the symbol for power?

[Fusione]

I can't find this anywhere, and as emberassed as I am to ask. What is the polarity of the symbol for power that looks like this.

____
_ _ _


I'm going crazy trying to find this info, but, can't find it anywhere.

Your help is greatly appreciated!

-Some guy who is too emberassed to post his real name.

 

[Overclocked]

You could use a voltmeter to determine the Polarity. If the volt meter reads negative, you have the polarity of the meter leads wrong. If you reverse it, you'll get a positive reading,then take note of the polarity of the meter leads.

 

[Fusione]

Hmm.. problem is it's not the source of the power that I'm finding this symbol on, it's the destination. I have an LCD that indicates the polarity of the 12vdc input using that symbol. I don't have the original power adapter, so I'm trying to figure out which way the polarity should go.

I've blown an LCD in the past due to hooking the power reversed-polarity (buying one big roll of black wire might be cheaper - until you fry and lcd, at least)

 

[Overclocked]

Hmm.. problem is it's not the source of the power that I'm finding this symbol on, it's the destination. I have an LCD that indicates the polarity of the 12vdc input using that symbol. I don't have the original power adapter, so I'm trying to figure out which way the polarity should go.

I've blown an LCD in the past due to hooking the power reversed-polarity (buying one big roll of black wire might be cheaper - until you fry and lcd, at least)

What LCD is it? Did you try looking up the data sheet?

 

[Fusione]

Yea.. It's a very rare daylight viewable LCD from a police car. (Bless ebay)

Datasheets are non-existant.. haha, I even tried looking for datasheets to other models, to see if they'd have this info.. but they don't.

I think I'm going to crack it open and trace the leads to see if i can find a hint of where things turn positive.

 

[Fusione]

Ok! (smack forehead) the entire thing is encased in aluminum. Of course it's grounded. Just texted continuity between the case and both terminals.

Roger Roger, We've found the ground

___ solid means ground

_ _ _ means power.



Nite everyone, and a happy holiday as well.

My mistake, please read kchriste's post below.

 

[kchriste]

That symbol just means that it'll take DC or pulsating DC as an input. If the LCD is is a metal case, one way of determining polarity is to ohm meter between a screw on the case and each side of the power plug. The one with a reading of 1ohm or less is the negative lead 99.999999% of the time. Things like the shell of a DB9/25 plug also are usually at ground potential also.

 

[audioguru]

Daylight viewable LCD? I can see my LCD watch when the sun is shining on it.
I can't see an LED display very well in daylight.

Is it a rear-lighted monitor LCD display for a pc? Mine is hard to see when the sun shines on it.

 

[Fusione]

It's a backlit sunlight viewable LCD that employs three methods for acheiving daylight viewability.

1. The touchscreen is bonded to the lcd itself, so theres fewer layers to reflect.

2. Theres more backlights. 6 times as many, actually. The measured output of this monitor is 1300 nits, roughly 6 times brighter than the average lcd

3. It's transflective. This means when sunlgiht hits it, it actually reflects the light back out.. making it BRIGHTER.

Your watch is what's called a reflective lcd. It requires ambient light to be reflected off it for viewability. A transmissive lcd is one that requires backlighting to see anything, and a transflective is one with a backlight, AND a semi reflective coating. Giving the best of both worlds.

Thanks for clarifying KChriste. I'll edit my post.

 

[Dean Huster]

As kchriste alluded, that symbol means nothing but "DC" and is not an indicator of polarity. It is most commonly found on digital multimeters to indicate a DCV or DCA function vs. an ACV or ACA function which is symbolized by a single-cycle sine wave. I wouldn't ever attempt to assign a polarity to the DC symbol (although on a DMM, the dotted line would indicate the ground/earth/zero-volt reference while the solid line would indicate the actual voltage). Most electronic critters designed for external power input usually state the polarity (e.g., center positive) or indicate polarity with a symbol. For electronic modules where the mark is on a circuit board, it's another deal altogether. That's why they print instruction sheets. If the module was harvested from something else, one tends to be on their own when figuring stuff like this out.

Dean

 

[Cabwood]

Don't go away from the experience believing this:

___ solid means ground
_ _ _ means power

because it's not true. The entire symbol stands alone on a diagram indicating some fixed voltage with respect to ground. Ground is completely different symbol somewhere else on the diagram. Continuing to believe this false conclusion will only end in tears.