Electronic Circuits Projects Diagrams Free

help diagnosing Nec lcd monitor

CalebG — Fri, 20 Nov 2009 23:51:21 GMT

hello I have been trying to find a fix for my 17" nec multisync lcd monitor. At startup the v-hold fails to hold, after a few minutes of warm up the v-hold corrects itself, but there are still many horizontal bars flickering across the screen, also I have a single pixel wide line down the left side about 2" in from the side. and last but not least the lower left backlight appears to be flickering. I am assuming I have a problem in the high voltage power supply, I replaced the electrolytic caps that I had spares for, there are still 3 that I didnt have replacements for. I have a capacitor meter on order that should be here in a few days. When I got the monitor it was stone dead, the power supply board appeared that something had been spilled in it, after cleaning off the goo on the board it sort of functions, I would love to get this fixed. What next? If anyone could pinpoint a likely source that would cause all the problems that would be awesome. I included a couple pics so you can see whats going on.

Thanks in advance Caleb :)

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PIC Barcode Project

rashidme — Fri, 20 Nov 2009 22:52:42 GMT

Hello,

Here is what I would like to design:

* A barcode is entered through a keypad connected to a microcontroller which in turn is connected to a PC.

* The barcode will be searched against a database on the PC and appropriate message will be displayed on the LCD display such as, No Item Found, Low Stock etc.

* The database will be updated based on actions such as if the item was sold or returned etc.

NOTE: I have a PIC Dem 2 board from microchip.

Thank you for any ideas and suggestion. :)

EEPROM Read/Write Cycle

birdman0_o — Fri, 20 Nov 2009 22:13:05 GMT

Just wondering what exactly the rating means.
For example a 24LC256 (32k eeprom) is rated a 1 000 000 read write, does this mean the whole device or one byte of memory.

Thanks

College student needs some feedback on a ping pong scorekeeper

BadgerMadison — Fri, 20 Nov 2009 21:41:33 GMT

Hi everyone,

This is my first post on Electro Tech. I am a first-year college student in an engineering program, and I was thinking of making a very simple ping pong scorekeeper for extra credit in a class I am taking. I took a look at some other posts, but they all seemed to be much more sophisticated, with a timer, and period indicator, and time-out indicators.

I would like to make a simple two digit score display (up to 21 points) Also, I would like to have a manual switch on each side of the table. When the switch is depressed, the score will increase, on that side, by one point. Finally I would like to make some kind of reset mechanism. It could be a third button, simply pulling a wire to remove the power, or once one side of the table reaches 21 points (button presses), the 22nd button press will bring the counter to zero.

I plan to use:

(2) two digit, seven segment displays, one per side (small, ~1 inch tall)

(2) simple manual switches, one per side

(1) power supply (9 volt battery perhaps?)

Some kind of a circuit board to connect everything to and provide programming necessary for operation. I don't really know what kind of circuit board will be sufficient for this project. Is this something I could ask someone at Radio Shack?

Any tips or pointers would be GREATLY appreciated, I really enjoy tinkering with little projects, but have only done "all-in-one kit projects" before. I want to step up to the big leagues and build my own little gadgets now that I'm in college.

electric touch- negative ion generator

xkhplaya — Fri, 20 Nov 2009 20:51:11 GMT

i'm creating a project known as pikashoes, electric touch, or electrifried

it requires a 12 vdc negative ion generator, however this item is difficult to obtain without overpaying or paying for expensive shipping online.
Anyone know where i'd be able to get a negative ion generator operating at 12 vdc??
Or anyone know what common household product or easy to obtain product without going online i could utilize and yank out the negative ion generator from??

Any size in necessary...

8051 assember help

fkuk — Fri, 20 Nov 2009 20:48:12 GMT

hi

i have this assignment that i have to do and what i need to do is create a 8051 assembler program
basicly convert binary to show decimal numbers on a 7 segment display
the binary numbers are input using switches on a project board and i need to program a ats8something

all i want to know is the steps i need to do to make this happen i probaly be able to program it
something like a flowchart would be helpful

thanks

help with vu meter and microphone

fkuk — Fri, 20 Nov 2009 20:07:47 GMT

hi

what im trying to do is make vu meter (lm3916) work with a microphone

but ive noticed that the microphone does not give enough voltage out, so i got a power amplifier (lm386) connected the mic to the amp and then to the vu meter

but all the lights light up

what am i doing wrong is it the amplifier?
if so how do i get it to work

thanks

Elektor Prelude preamp

srcmmr — Fri, 20 Nov 2009 19:57:56 GMT

Hi to everyone,
I am new memeber and i was addressed her from the net.
I found some old copies of Elektor magazine, particulary parts of them, which described a project for an audio preamp called Prelude. Do any of you know something about that? Do any of you ever bulit it?
Any feedback is welcome
Many thanks in advance
srcmmr

quick question

oem_odm — Fri, 20 Nov 2009 17:49:09 GMT

just'a quicky

if 2 IR leds are emitting towards a standard IR receiver module, each having slightly different encoded message - will the single IR receiver module be alright for detecting the encoded message....

(and :-o should the encoded message be cosntructed in an particular way, i.e. unique id at beginning or end) - i have no idea about the actual encoding...just surface level so please excuse my approach

thanks

Wall climbing..

Electronman — Fri, 20 Nov 2009 17:35:04 GMT

Climb wall car (Remote control)

Want to know how it does work??

Why the voltmeter Shows this?

Electronman — Fri, 20 Nov 2009 17:14:26 GMT

Hi,

Why the voltmeter shows 12V while the above SW is open And was open before( I never closed it!)?

Thanks

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Led based holographic display

sahu — Fri, 20 Nov 2009 17:01:32 GMT

i want LED BASED HOLOGRAPHIC MOVING MSG. DISPLAY. pl help me any body....................

CMOS Inverter 12V INPUT to PIC INPUT

007tiger — Fri, 20 Nov 2009 16:23:49 GMT

I am trying to find a way to replace a reed relay with solid state components.

I have a 12 volt input coming from a remote switch. The system currently turns on a relay that will pull the pic input to ground. The pic input is normally pulled up to 5v.

I think I can use the bottom circuit with a CMOS 4069 inverter to take the 12v input and generate a 5v ttl output. In this circuit the inverter input is pulled low to give me the high output to the PIC. When the switch is pressed the inverter input goes high (+12vdc) and causes the output to go low (<.5vdc) and pull the pic input to ground.

Looking at the data sheet I think I actually have to supply the cmos with 12vdc but this would then give a Vout High of 14.95 volts.

If I keep the CMOS with a 5vdc supply should I use a voltage divider on the input of the CMOS to get the voltage in the 0-5vdc range?

Or is there a better way of doing this? The relay coil adds noise, need a diode for emf and also has a limited mechanical life span, thus I am looking at a more robust solid state design.

Thanks

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prolong halogen lamp life (burns from 240V AC)

smilem — Fri, 20 Nov 2009 16:12:55 GMT

Prolong halogen lamp life (burns from 240V AC)

Hi, I have problem with halogen lamps, they are rated for 230V AC.

However I have 240V AC at day time and at nights 245V AC.

I was thinking to use 100Ohm 5W resistor for 40W lamp
and 33Ohm 10W for 100W lamp. The only disadvantage is that the power is wasted (used to heat the room :( ).

Is there any other way besides using resistor to make correct 220V instead of 240V AC?

jdm progr.

sahu — Fri, 20 Nov 2009 16:08:09 GMT

i am using jdm progr.one time i prog . a micro controller ,after that i want chang only config , not program code and not eeprom code. how can do it ? pl help me.............