Rapid Sale

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nickpatts

Member
Hi All,

Just a heads up for uk buyers, rapidonline are having a sale midnight wednesday for 24hrs, this is end column prices so you get the cheapest price regardless of quantity, this includes picaxe chips and lots of other goodies,

while on the subject of rapid has anyone played around with the 16-Channel constant current LED driver (CAT4016) at 32p sale price im going to give them a go, looks to be very simular to controlling a 75hc595 chip but has the advantage of runing 16 leds straight from the chip with one resistor determin the current for all the leds also can be daisy chained.


admin note, please remove if i am not allowed to advertise a particular site but I deemed it of interest to picaxe users.
 
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Andrew Cowan

Senior Member
Thanks for that - where did you find that out? I couldn't find a link on rapid's homepage...

That chip looks very nice - seems to just be a simple shift register interface. BLANK is on/off control of the LEDs.

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eclectic

Moderator
@nick

Thanks for the link to the Sale.
I'll try not to forget, like I did on the last end-column time! :-(

That looks a great chip for the Sale price.

Now, I'm only speaking personally, but
I cannot make and drill SOIC 24 boards.

On a good day, I might just be able to solder 1.27 mm
to a SOIC-DIP adapter.
But, up goes the price and the board-space.

e
 
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Dippy

Moderator
Yes, I agree. SOIC much easier than TSSOP. Espcially on home-brew boards where you don't have solder resist.

Looks a nice chip and a great price.
I've never used one but it looks dead easy (i.e. a piece of cake) to interface too.

I have one suggestion, (though at that price it's significance is reduced).
That is to get a SOIC-DIP/DIL adaptor.
With a PCB with solder-resist you are less likely to have solder wicking under the device and between pins.
Yes, I know it costs a few quid. But if you mess up on your PCB then you can just unplug it and pop it into your MK2,3,4,5 board.
But as I say, at that price a couple of cockups won't cost the price of an adaptor.
Though, with an adaptor you can stick it in breadboard.
Maybe make an adaptor.
Anyway, it's just a thought.

EC, why would you want to drill a SOIC board? You got some kind of 0.5mm fettish?
A man of your calibre, with a pile of ferric Chloride could easily do SOIC.
And then a fine felt tip pen for your solder resist :)
 
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eclectic

Moderator
Dippy said:
EC, why would you want to drill a SOIC board? You got some kind of 0.5mm fettish?
A man of your calibre, with a pile of ferric Chloride could easily do SOIC.
And then a fine felt tip pen for your solder resist :)
Click to expand...
Reason 1.
So I could "plug" the damned thing in.

Reason 2.
Oh all right, I made a mistake. :)

And, how did you find out about my fetish? :)

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Dippy

Moderator
I thought everyone knew!

It was in the main Editorial of "Hobby Drills Monthly" magazine.

Just beneath that article on kit milling machines which claimed 0.00045mm accuracy, I forget what make. Oh yes, I remember now, it was made by "Dream On Inc.".
 
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SilentScreamer

Senior Member
This might be obvious but how do you get the reduction. I added items to my basket and it was still the original price? Does it do it later or am I missing something?
 
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Dippy

Moderator
Well the mailshot says
"All orders placed between Midnight Wednesday 18th to Midnight Thursday 19th 2009" (UK time)

I usually get muddled with semantics, but maybe midnight TONIGHT is Midnight Wednesday.

Solution: Ring 'em up!!
 
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Dippy

Moderator
I'm proud of you SS.
SOME people would have simply edited their previous post to cover the red-face-situation.
 
hippy

hippy

Ex-Staff (retired)
Midnight, noon, 12am and 12pm are terms which are best avoided, not just because of ambiguity and different cultural usages but because it always means making others second guess if what is perceived is what was intended, and never being sure they will guess right.

The root problem is that midnight and noon are the instantaneous transitions from one time period to another and therefore have no length in themselves.

Dead on 12 o'clook noon and 12 o'clock midnight are neither "am" nor "pm" but the real world has to decide how a 12 hour clock terms the period immediately after that transition. Logically, by literal definition, the period after passing through noon should be post-meridian, thus "pm", but not all authorities or government bodies agree. One man's 12:00pm is just after noon, another's 12:00pm is just after midnight.
 
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Dippy

Moderator
I'm sure this highly interesting thesis could roll for days - maybe even a few midnights will pass.

And a phone call would take, what shall we say, 10 seconds.

To me 'midnight' is a midpoint and therefore an infintely small boundary which defines one day from another i.e. that teeny weeny boundary at the end of a calender day when the date changes. Period.

If it was anything else then when you phoned your friends and said you'd meet up at "midnight tonight", then you would have missed them :)

But as I said, a 10 second phone call would have cleared it. But the Forum MAMOOAM syndrome strikes again, bless 'em.
 
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slurp

Senior Member
In a business that works around the clock we gernally use 2359 or 0001 to avoid the confusion.

Saying midnight Wednesday to midnight Thursday might be clearer with 2359 Wednesday to similar Thursday or 0001 to 2359 thursday... but I guess that's just a little short of a 24 hour sale :D

From the NPL's FAQ on time....

Does 'midnight' belong to the day before or the day after?

The short answer is 'yes'.... NPL FAQ

regards,
Colin
 
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SilentScreamer

Senior Member
Personally I'd round it to the next day (e.g Thursday in this case) because when rounding numbers 0.5 goes to 1. Also on 24 hour clocks 0:00 is the next day not 24 hours past the last day.
 
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MORA99

Senior Member
nickpatts said:
...looks to be very simular to controlling a 75hc595 chip but has the advantage of runing 16 leds straight from the chip with one resistor determin the current for all the leds also can be daisy chained.
Click to expand...
If you need many leds 5450/5451 can be used also, works with simple shift (no latch, since they cant chain) gives 34-35outputs (sink) with 15mA limit each, 1 common resistor for brightness.

If less than the full chip is used the other outputs can be ran with higher mA.
It gets very hot, but datasheet says its protected against meltdown etc.
And its DIP package :)
 
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slurp

Senior Member
SilentScreamer said:
Personally I'd round it to the next day (e.g Thursday in this case) because when rounding numbers 0.5 goes to 1. Also on 24 hour clocks 0:00 is the next day not 24 hours past the last day.
Click to expand...

So is 00:00 Friday just after 23:59 Tursday or just before 00:01 Saturday? :confused:
 
hippy

hippy

Ex-Staff (retired)
00:00 Friday would follow 23:59 Thursday. Just before 00:01 Saturday would be 23:59 Friday then 24:00 Friday / 00:00 Saturday.
 
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SilentScreamer

Senior Member
MORA99 said:
If you need many leds 5450/5451 can be used also, works with simple shift (no latch, since they cant chain) gives 34-35outputs (sink) with 15mA limit each, 1 common resistor for brightness.

If less than the full chip is used the other outputs can be ran with higher mA.
It gets very hot, but datasheet says its protected against meltdown etc.
And its DIP package :)
Click to expand...
Does rapid stock the 5450 or 5451?
 
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MORA99

Senior Member
SilentScreamer said:
Shame, any ideas to get 88 outputs? :confused: (all LEDs and they all need to be independent)
Click to expand...
3 chips (from somewhere else), although in DIP40 they take up a lot of room. (6pins needed, or put clock together and shift out all 3 at time = 4pins)
Or multiplex... (will probaly need a seperate chip since it will be pretty busy with just the multiplexing)
Or 11x74HC595 chained (3pins needed)(Will need resistor or pwm controling the current)
 
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MORA99

Senior Member
SilentScreamer said:
Is there any good threads or guides to multiplexing (I have very little idea of how to do it)
Click to expand...
Use the search function at the top theres many threads.
Heres one way to do it http://en.wikipedia.org/wiki/Charlieplexing

An easyier way is to have x outputs controlling rows, and y outputs controlling colum.
So you enable one row, and then light up the leds.
Then turn off leds, select next row, light up leds
and repeat.

When done fast enough, it will look like all leds are on, although they are being turned on/off many times a second.

This way for 10pins you can get 25leds instead of just 10. (5rows of 5leds)
(add a pin more and you get 5 more leds)
 
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