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61  Using Arduino / Displays / Re: Are lcd's displays effected by Direct Light (not sunlight) mine is on: February 12, 2013, 09:07:49 am
hi john
its really strange, ive tryed blocking out different parts of the display does this same gets dim in direct light, as soon as you angle it out of the light characters go bright a fraction of a second later, like an auto contrast display i soppose, but its not an auto contrast display
 
but its defiantly sensitive to bright natural light, not sensitive to artificial light at all, its one of these ebay specials, had a really good look at the display cant see any sort of light sensor

been playing with it for ages now its defiantly trying to auto contrast, in some way.

(ive got another display an auto contrast, it has a small sensor in the black front face, nothing like this one)

http://www.ebay.co.uk/itm/160930204992?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
62  Using Arduino / Displays / Are lcd's displays effected by Direct Light (not sunlight) mine is on: February 12, 2013, 08:26:34 am
hi,

got a really strange lcd problem, im using a bog standard 4 line 20 character display no problems at all been working fine for a couple of months now

i noticed a few times early on the display acting strangely the characters went really dim couldnt work out what was causing it.

fast faward 2 months finally worked out what is causing it, had the display close to a window the display went really dim all characters,  then took it away from the strong light not sun light into a normal lit room the characters returned to normal operation

is this normal?   
63  Using Arduino / General Electronics / Re: Chinese Pcb Manufacturer Reccomendation. on: February 12, 2013, 04:16:41 am
After seeing this I thought I'd email Sitopway for a quote.

Just received it and they quoted me 50USD for 10pcs 100mm x 100mm dual layer, red soldermask, top/bottom silkscreen on 16mm FR4.

That's 20USD more than Elecrow, so looks like I'll be sticking with them.

The OP said 5.2GBP for 130mm x 140mm, so I wonder if that was just per single PCB, ie 10 pcs was 52GBP? That would make more sense at about 80-90USD for 10 pcs 130mm x 140mm, based on what they have quoted me.


the board was double sided, 5.2 each including postage 7 day turnaround, for a 130mm by 140mm board, 81usd total
64  Using Arduino / General Electronics / Re: Understanding ACS7xx Current Sensor on: February 10, 2013, 03:37:45 pm
yes the output is very stable im measuring ac current, pvm out of a frequency inverter, my output is really stable nice sign wave no noise.

im using the suggested circuit in the data sheet, 1nf across pin 5 and 6
65  Using Arduino / General Electronics / Re: Understanding ACS7xx Current Sensor on: February 10, 2013, 02:00:14 pm
What resistance does your meter read:

(a) when you press the probes directly on to the leads of the chip;

(b) when you press the probes against each other?

ok, slight change probably due to temp.

leads shorted 0.2 ohms,

across ic pins and connector 0.2 ohms, on my fairly new fluke meter

this is a pic of my application of the ic
66  Using Arduino / General Electronics / Re: Understanding ACS7xx Current Sensor on: February 10, 2013, 01:21:39 pm
ok had another look at the data sheet
 
i cant find any mention of heatsinking,

i really dont understand where this heat would be coming from in the first place,  the current passes between IP+ (pins 1 and 2) and IP- (pins 3 and 4) the resistance is 0.3 ohms how can this generate any heat?  

Can't be .3 ohms and still rated for 30amps. Amps squared X R loss would blow the whole module up.

Lefty

here is a pic of the internals of the ic, of the ic pins 1,2 connected to 3,4 i measured it this morning 0.3 ohms
67  Using Arduino / General Electronics / Re: Understanding ACS7xx Current Sensor on: February 10, 2013, 06:42:36 am
ok had another look at the data sheet
 
i cant find any mention of heatsinking,

i really dont understand where this heat would be coming from in the first place,  the current passes between IP+ (pins 1 and 2) and IP- (pins 3 and 4) the resistance is 0.3 ohms how can this generate any heat?  
68  Using Arduino / General Electronics / Re: Understanding ACS7xx Current Sensor on: February 09, 2013, 04:13:42 am
ive been using that 30a chip up to 9 amps and not noticed any heat issues as discussed earlier in the thred, i suspect my heat is sunk through the connector i am using as its so close to the ic, i am  measuring a single ac 230 phase

they are very sensitive to how you lay them out on the pcb, if you dont get it right they dont work, took me a few attempts

in the data sheet there is an explanation on the best method of board design

note, obviously make sure the connector you use is capable of what current you are measuring, not all the small breakout boards that are sold everywhere are capable of handling their intended currents (the connectors). on my board i fill the track with extra solder from the ic pin to the pin of the connector just to be safe.

if you want i can send you the pcb design file, i use Design Spark free its a really great package cant recommend it enough.
69  Using Arduino / General Electronics / Re: Understanding ACS7xx Current Sensor on: February 08, 2013, 04:04:51 pm
what does the output look like with zero load? should be 2.5v
70  Using Arduino / General Electronics / Re: Whats the best method to switch 4 relays from 1 output? on: February 07, 2013, 08:17:44 am
i did think of doing it that way but not much choice on 5v, i  wanted to make it bomb proof, i intend using a 8a dp contacts doubling up on those  giving me 16a
cheers
71  Using Arduino / General Electronics / Re: Whats the best method to switch 4 relays from 1 output? on: February 07, 2013, 07:23:30 am
hi micheal , no the 230v's are seperate live feeds fused to 3a each which turn on various things
72  Using Arduino / General Electronics / Re: Understanding ACS7xx Current Sensor on: February 07, 2013, 07:11:33 am
Those sensors are noisy. I have even more noise than you.
Those sensors pick up any magnetism from transformers nearby. Both normal 50Hz/60Hz transformers and also high frequency switching power supply transformers.

I live in Europe, with 50Hz mains. So I use the average during 20ms, to measure DC current.
But it still is not very stable.

If you look at the Pololu breakout board, the current side copper on the pcb is near the sensor output side. For high voltages it should be as far as possible away from the sensor output side.



please can you explain by what you mean noisy? do you mean emit noise / electrical noise?
73  Using Arduino / General Electronics / Re: Whats the best method to switch 4 relays from 1 output? on: February 07, 2013, 03:17:16 am
think my best / easiest option is to use one transistor switching 4 coils in parallel, thanks for the help
74  Using Arduino / General Electronics / Re: Cheap Uk Supplier for 2.54mm Header Pin Connectors ? on: February 06, 2013, 08:22:57 am
i get everything from china, have to wait a bit but always arrives

im in the uk, to get the best prices, log onto usa ebay then search for whatever, if you cant wait rapid electronics 
75  Using Arduino / General Electronics / Whats the best method to switch 4 relays from 1 output? on: February 06, 2013, 06:39:20 am
hi
id like to switch 4 * 5v relays switching 4 * 230v feeds,  from just 1 output from my 328

just wondering what is the best way / method for doing this?

thanks
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