BasicStamp2 and 4528 One Shot
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I've tried hooking up a 4528 one shot just like the "Positive One-
Shot" on page 27 of Forrest Mims' "Engineer's Notebook".
I want to trigger on a brief pulse so that my stamp can catch
the wider one-shot pulse in a loop.
I've got a 100uF electrolytic cap and a 10K resistor to set the pulse
width, which works out to .5RC so says Forest which figures out to
about a half a second.
No matter what I apply to pin 4 on the 4528 I can only get the one-
shot to send out the pulse when I first apply power to it
Anyone got any tips on one-shots?
Mark
Shot" on page 27 of Forrest Mims' "Engineer's Notebook".
I want to trigger on a brief pulse so that my stamp can catch
the wider one-shot pulse in a loop.
I've got a 100uF electrolytic cap and a 10K resistor to set the pulse
width, which works out to .5RC so says Forest which figures out to
about a half a second.
No matter what I apply to pin 4 on the 4528 I can only get the one-
shot to send out the pulse when I first apply power to it
Anyone got any tips on one-shots?
Mark
Comments
You will have much better luck with a larger R and smaller C. The original
RCA data sheets for the 4528 (and it's little brother the 4538) warn
against large value electrolytic caps (100µF would qualify, here). I don't
see it in the current data sheets from Motorola or National. They do,
however, point out the other problem with large caps; the need to add a
series reverse biased diode to Vdd to protect against power surges on power
down.
In non-retriggerable monostable mode with a rising edge trigger, connect
pin 5 to 7, connect input to pin 4, connect pin 3 to Vdd, connect pin 1 to
Vss (gnd), connect your cap between pin 1 and 2, connect your resistor
between pin 16 (Vdd) and pin 2.
Make sure that you tie unused inputs to ground on the unused section.
Try a 1M resistor and a 1µF. You'll find it works just as well!
Mike
At 03:36 PM 6/17/2001 +0000, you wrote:
>I've tried hooking up a 4528 one shot just like the "Positive One-
>Shot" on page 27 of Forrest Mims' "Engineer's Notebook".
>
>I want to trigger on a brief pulse so that my stamp can catch
>the wider one-shot pulse in a loop.
>
>I've got a 100uF electrolytic cap and a 10K resistor to set the pulse
>width, which works out to .5RC so says Forest which figures out to
>about a half a second.
>
>No matter what I apply to pin 4 on the 4528 I can only get the one-
>shot to send out the pulse when I first apply power to it
>
>Anyone got any tips on one-shots?
>
>Mark
>
>
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_________________________________
Mike Walsh
walsh@i...