Interesting thing about the 2.5" LCD A/V Display

kerryw

I wanted to use the 2.5" LCD display for a robot project. Unfortunately the 12 volt power supply requirement of the display was a problem. Everything I was using was 7.2 volts (servos) or less. On a whim I plugged in the 7.2 volt battery supply into the display and found out that it does work at that voltage. I'm guessing that the 12 volt in was due to the manufacturer thinking that it would be used primarily in an automotive environment.

Kerry

parts-man73

Actually, if you have the April 2006 edition of Nuts and Volts magazine take a look at the cover photo of the demo board, with the attached Pustom screen. The power cable plugged into the screen is labeled "7.5 VDC"

Just an observation.

rokicki

Mine runs surprisingly hot at 12V. I'll have to see if 7.5V doesn't allow it to run cooler.

I'm almost tempted to use my bench DC supply and see how low it will go. I wonder
if I can break it by feeding too little voltage?

LoopyByteloose

Coincidentally, I used a wall wart that was outputing 12.3 volts unloaded.· Later I checked the lable to find that it is a 7.5DC wall wart.· The 2.5"video ran fine.· I again looked at the loaded condition and found it running at 7.98 volts.· Generally, the wall warts drive me crazy with doubts about their output control.

The fact that·this runs cooler and the fact that this is closer to an overall system supply makes me want to continue with the lower voltage too.· I have a Gel cell setup at 8 volts DC that is optimal for me.· I don't worry about the wall warts and the 9amp hours mean very little time recharging.

From what I understand is that 'over-voltage' equals excessive force which·likely will·burn out anything above the rated voltage. Or at least cause it to age more quickly.

Still I have serous doubts about safe 'under-voltage' operation.

'Under-voltage' is really a brown-out or power down situation where function usually becomes less reliable.··The common transistion through this region is intended to be momentary, not sustained.· It seems to me that in a simple system, that would not have any long term consequences.·

Still, I fear there are no guarentees when using devices that convert to different voltages [noparse][[/noparse]and that may be the case with a video display]·as running 'outside specification' may move a voltage converter into an unstable mode.·

Does anyone have a good way [noparse][[/noparse]other than simply testing until failure] to determine the safety?·

Please consider...

Several months back I was sold·a couple·230VAC florecent bulbs that I could not return.· I happen to have a 230VAC outlet next to my bed [noparse][[/noparse]for an air conditioner], so I have my lamp plugged into it and still operating.· The other one·intially operated okay in 110VAC and I used it in the bathroom.· This one failed after 2-3 months.·


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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan

Post Edited (Kramer) : 6/2/2006 8:34:27 AM GMT

kerryw

I have found that the display runs considerably cooler at the lower voltage. I have also noticed no difference in functionality (brightness etc.).

Kerry