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Separate pulses from edges?

T

Terry Pinnell

Jan 1, 1970
0
I have a long, clean positive pulse (hours in duration). How can I get
two *separate* 10 ms +ve pulses from the leading and trailing edges
please?

A simple RC differentiator (of appropriate polarity) would be the
obvious solution if I only wanted one or the other. But I can't figure
out how to get *both*, as separate signals.

FWIW, I want to take these pulses to the Set and Reset pins of a 4013.
 
J

John O'Flaherty

Jan 1, 1970
0
Terry said:
I have a long, clean positive pulse (hours in duration). How can I get
two *separate* 10 ms +ve pulses from the leading and trailing edges
please?

A simple RC differentiator (of appropriate polarity) would be the
obvious solution if I only wanted one or the other. But I can't figure
out how to get *both*, as separate signals.

You could use a dual 555 timer, with one trigger driven by the signal
directly, and one driven by the inverse.
FWIW, I want to take these pulses to the Set and Reset pins of a 4013.

It seems like that would recreate the original signal, or its inverse.
Why would you do it?
 
B

bruce varley

Jan 1, 1970
0
Terry Pinnell said:
I have a long, clean positive pulse (hours in duration). How can I get
two *separate* 10 ms +ve pulses from the leading and trailing edges
please?

A simple RC differentiator (of appropriate polarity) would be the
obvious solution if I only wanted one or the other. But I can't figure
out how to get *both*, as separate signals.

FWIW, I want to take these pulses to the Set and Reset pins of a 4013.
 
B

bruce varley

Jan 1, 1970
0
Terry Pinnell said:
I have a long, clean positive pulse (hours in duration). How can I get
two *separate* 10 ms +ve pulses from the leading and trailing edges
please?

A simple RC differentiator (of appropriate polarity) would be the
obvious solution if I only wanted one or the other. But I can't figure
out how to get *both*, as separate signals.

FWIW, I want to take these pulses to the Set and Reset pins of a 4013.

Terry, Too late at night here to think through the details, but in general,
a simple way to do what you want is as follows (example):

Feed the input signal through a resistor to the input of an inverter, with a
cap to ground on the input pin of the inverter. The output of the inverter
will then be a somewhat delayed, inverted form of the original input pulse.
If you then take the original input signal and the output of the inverter,
and connect them to the 2 inputs of an AND gate, then the output of the AND
will be a positive pulse, with duration determined by the time constant
(order of R*C) of the R and C you used.

The negative edge can also be obtained easily with a similar approach, just
inverting the various signals as required. It can all be done with your
4001s.

Maybe someone where it isn't way after midnight might care to expand.
 
J

John Popelish

Jan 1, 1970
0
Terry said:
I have a long, clean positive pulse (hours in duration). How can I get
two *separate* 10 ms +ve pulses from the leading and trailing edges
please?

A simple RC differentiator (of appropriate polarity) would be the
obvious solution if I only wanted one or the other. But I can't figure
out how to get *both*, as separate signals.

FWIW, I want to take these pulses to the Set and Reset pins of a 4013.
If you want to get a similar output regardless of the transition
direction, delay the signal with an RC and combine it with the
original with an exclusive or gate. The RC time constant determines
the edge generated pulse width.
 
J

John Popelish

Jan 1, 1970
0
John said:
If you want to get a similar output regardless of the transition
direction, delay the signal with an RC and combine it with the original
with an exclusive or gate. The RC time constant determines the edge
generated pulse width.

Of course, if you have no other use for the extra 3 gates in the exor
package, you can use them to delay the signal, instead of the RC.
 
M

Mike

Jan 1, 1970
0
I have a long, clean positive pulse (hours in duration). How can I get
two *separate* 10 ms +ve pulses from the leading and trailing edges
please?

A simple RC differentiator (of appropriate polarity) would be the
obvious solution if I only wanted one or the other. But I can't figure
out how to get *both*, as separate signals.

FWIW, I want to take these pulses to the Set and Reset pins of a 4013.

You could use a 4528 or 4538 dual monostable. One setup for pos edge
trigger and the other for neg edge trigger. Set the pulse widths with
2 RC networks and select which outputs, Qs or not Qs, you want to use.

Mike
 
T

Tim Williams

Jan 1, 1970
0
John Popelish said:
Of course, if you have no other use for the extra 3 gates in the exor
package, you can use them to delay the signal, instead of the RC.

ms, not ns. (Would still trigger the 4013 though...)

Tim
 
R

Rich Grise

Jan 1, 1970
0
I have a long, clean positive pulse (hours in duration). How can I get
two *separate* 10 ms +ve pulses from the leading and trailing edges
please?

A simple RC differentiator (of appropriate polarity) would be the
obvious solution if I only wanted one or the other. But I can't figure
out how to get *both*, as separate signals.

FWIW, I want to take these pulses to the Set and Reset pins of a 4013.

Invert one and OR them? What kind of skew can you tolerate?

Thanks,
Rich
 
P

prateek

Jan 1, 1970
0
I feel 555 can not be used in the monostable mode. It is agreed that
the trigger by the falling edge will actuate the monostable but since
the trigger pulse is in hours and we require output pulse width in
msec, the trigger should have returned to its hight state before the
1.1x(RC) secs, which is the on time for the ouput pulse. If not the
output pulse remains high. So for monostable operation the negative
trigger pulse width should be less than 1.1x(RC) secs.

prateek
 
J

John Fields

Jan 1, 1970
0
If you want to get a similar output regardless of the transition
direction, delay the signal with an RC and combine it with the
original with an exclusive or gate. The RC time constant determines
the edge generated pulse width.

---
Unfortunately, since this is what he wants:

___________...___________ ________
IN____| |___________...___________|

_ _
OUTA__| |_________..._______________________...___________| |______

_
OUTB______________...___________| |_________...____________________


and what you suggested will give him this:

___________...___________ ________
IN____| |___________...___________|

_ _ _
OUTA__| |_________...___________| |_________...___________| |______

_ _ _
OUTB__| |_________...___________| |_________...___________| |______


your outputs won't set and reset his RS latch properly.


This seems to work:



Version 4
SHEET 1 880 680
WIRE -224 192 -224 -32
WIRE -224 256 -224 192
WIRE -224 320 -224 256
WIRE -224 464 -224 400
WIRE -224 512 -224 464
WIRE -176 -32 -224 -32
WIRE -176 256 -224 256
WIRE -80 256 -112 256
WIRE -80 320 -80 256
WIRE -80 464 -224 464
WIRE -80 464 -80 400
WIRE -64 -16 -112 -16
WIRE -64 -16 -64 -80
WIRE -48 192 -224 192
WIRE -48 256 -80 256
WIRE -16 -16 -64 -16
WIRE 80 -16 48 -16
WIRE 80 16 80 -16
WIRE 80 128 80 96
WIRE 112 -80 -64 -80
WIRE 112 -16 80 -16
WIRE 112 240 16 240
WIRE 224 -64 176 -64
WIRE 224 16 224 -64
WIRE 224 128 224 96
WIRE 224 240 176 240
WIRE 224 320 224 240
WIRE 224 464 -80 464
WIRE 224 464 224 400
WIRE 320 -64 224 -64
WIRE 320 240 224 240
FLAG -224 512 0
FLAG 80 128 0
FLAG 224 128 0
SYMBOL Digital\\and -16 160 R0
SYMATTR InstName A1
SYMATTR SpiceLine trise 1e-6s tfall 1e-6s vhigh 5v
SYMBOL res -64 416 R180
WINDOW 0 -42 69 Left 0
WINDOW 3 -48 37 Left 0
SYMATTR InstName R1
SYMATTR Value 1E6
SYMBOL cap -112 240 R90
WINDOW 0 65 33 VBottom 0
WINDOW 3 67 34 VTop 0
SYMATTR InstName C1
SYMATTR Value .015E-6
SYMBOL voltage -224 304 R0
WINDOW 0 -49 10 Left 0
WINDOW 3 24 104 Invisible 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value PULSE(0 5 0 1e-6 1e-6 5 10)
SYMBOL Digital\\and 144 160 R0
SYMATTR InstName A2
SYMATTR SpiceLine trise 1e-6s tfall 1e-6s vhigh 5v
SYMBOL res 208 304 R0
SYMATTR InstName R2
SYMATTR Value 10k
SYMBOL Digital\\and -144 -96 R0
SYMATTR InstName A3
SYMATTR SpiceLine trise 1e-6s tfall 1e-6s vhigh 5v
SYMBOL Digital\\and 144 -112 R0
SYMATTR InstName A4
SYMATTR SpiceLine trise 1e-6s tfall 1e-6s vhigh 5v
SYMBOL cap 48 -32 R90
WINDOW 0 61 28 VBottom 0
WINDOW 3 65 30 VTop 0
SYMATTR InstName C2
SYMATTR Value .015E-6
SYMBOL res 96 112 R180
WINDOW 0 -43 70 Left 0
WINDOW 3 -47 43 Left 0
SYMATTR InstName R3
SYMATTR Value 1E6
SYMBOL res 208 0 R0
WINDOW 0 39 48 Left 0
SYMATTR InstName R4
SYMATTR Value 10k
TEXT -328 448 Left 0 !.tran 30
TEXT 328 240 Left 0 ;OUTA
TEXT 328 -64 Left 0 ;OUTB
 
J

John Fields

Jan 1, 1970
0
I feel 555 can not be used in the monostable mode. It is agreed that
the trigger by the falling edge will actuate the monostable but since
the trigger pulse is in hours and we require output pulse width in
msec, the trigger should have returned to its hight state before the
1.1x(RC) secs, which is the on time for the ouput pulse. If not the
output pulse remains high. So for monostable operation the negative
trigger pulse width should be less than 1.1x(RC) secs.

---
You misunderstood.

He has a signal which periodically changes state, and when it goes
high he wants to SET what amounts to an RS flip-flop. Then when his
signal goes low he wants to RESET the flip-flop.

All that's necessary to do to drive 555's with that is to invert the
input signal, differentiate the falling edges of both the incident
ind inverted signals, and use those low-going spikes to drive 555''s
with 10ms timeouts. However, as you noted, the spikes will need to
return to >= 2/3 Vcc before the 555's time out.
 
John said:
On Sat, 24 Jun 2006 12:18:47 -0400, John Popelish


---
Unfortunately, since this is what he wants:

___________...___________ ________
IN____| |___________...___________|

_ _
OUTA__| |_________..._______________________...___________| |______

_
OUTB______________...___________| |_________...____________________


and what you suggested will give him this:

___________...___________ ________
IN____| |___________...___________|

_ _ _
OUTA__| |_________...___________| |_________...___________| |______

_ _ _
OUTB__| |_________...___________| |_________...___________| |______


your outputs won't set and reset his RS latch properly.


This seems to work:



Version 4
SHEET 1 880 680
WIRE -224 192 -224 -32
WIRE -224 256 -224 192
WIRE -224 320 -224 256
WIRE -224 464 -224 400
WIRE -224 512 -224 464
WIRE -176 -32 -224 -32
WIRE -176 256 -224 256
WIRE -80 256 -112 256
WIRE -80 320 -80 256
WIRE -80 464 -224 464
WIRE -80 464 -80 400
WIRE -64 -16 -112 -16
WIRE -64 -16 -64 -80
WIRE -48 192 -224 192
WIRE -48 256 -80 256
WIRE -16 -16 -64 -16
WIRE 80 -16 48 -16
WIRE 80 16 80 -16
WIRE 80 128 80 96
WIRE 112 -80 -64 -80
WIRE 112 -16 80 -16
WIRE 112 240 16 240
WIRE 224 -64 176 -64
WIRE 224 16 224 -64
WIRE 224 128 224 96
WIRE 224 240 176 240
WIRE 224 320 224 240
WIRE 224 464 -80 464
WIRE 224 464 224 400
WIRE 320 -64 224 -64
WIRE 320 240 224 240
FLAG -224 512 0
FLAG 80 128 0
FLAG 224 128 0
SYMBOL Digital\\and -16 160 R0
SYMATTR InstName A1
SYMATTR SpiceLine trise 1e-6s tfall 1e-6s vhigh 5v
SYMBOL res -64 416 R180
WINDOW 0 -42 69 Left 0
WINDOW 3 -48 37 Left 0
SYMATTR InstName R1
SYMATTR Value 1E6
SYMBOL cap -112 240 R90
WINDOW 0 65 33 VBottom 0
WINDOW 3 67 34 VTop 0
SYMATTR InstName C1
SYMATTR Value .015E-6
SYMBOL voltage -224 304 R0
WINDOW 0 -49 10 Left 0
WINDOW 3 24 104 Invisible 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value PULSE(0 5 0 1e-6 1e-6 5 10)
SYMBOL Digital\\and 144 160 R0
SYMATTR InstName A2
SYMATTR SpiceLine trise 1e-6s tfall 1e-6s vhigh 5v
SYMBOL res 208 304 R0
SYMATTR InstName R2
SYMATTR Value 10k
SYMBOL Digital\\and -144 -96 R0
SYMATTR InstName A3
SYMATTR SpiceLine trise 1e-6s tfall 1e-6s vhigh 5v
SYMBOL Digital\\and 144 -112 R0
SYMATTR InstName A4
SYMATTR SpiceLine trise 1e-6s tfall 1e-6s vhigh 5v
SYMBOL cap 48 -32 R90
WINDOW 0 61 28 VBottom 0
WINDOW 3 65 30 VTop 0
SYMATTR InstName C2
SYMATTR Value .015E-6
SYMBOL res 96 112 R180
WINDOW 0 -43 70 Left 0
WINDOW 3 -47 43 Left 0
SYMATTR InstName R3
SYMATTR Value 1E6
SYMBOL res 208 0 R0
WINDOW 0 39 48 Left 0
SYMATTR InstName R4
SYMATTR Value 10k
TEXT -328 448 Left 0 !.tran 30
TEXT 328 240 Left 0 ;OUTA
TEXT 328 -64 Left 0 ;OUTB

I could not come up with an unambigious understanding of what he wants,
so I prefaced my reply with "If". I am still not sure what he wants.
 
T

Terry Pinnell

Jan 1, 1970
0
Terry Pinnell said:
I have a long, clean positive pulse (hours in duration). How can I get
two *separate* 10 ms +ve pulses from the leading and trailing edges
please?

A simple RC differentiator (of appropriate polarity) would be the
obvious solution if I only wanted one or the other. But I can't figure
out how to get *both*, as separate signals.

FWIW, I want to take these pulses to the Set and Reset pins of a 4013.

Thanks guys, much appreciate all the replies. Some neat ideas to
follow up there.

But even while composing my OP it was nagging away at me that I'd
asked essentially the same question before. Further digging this
morning turned it up:
Subject: 2 pulses from 1
Date: Mon, 28 Feb 2005

Premature senility aside, I'm guessing that the reason it had slipped
my mind was that, although I had two great solutions from Fred Bartoli
and Fred Bloggs, I'd managed to come up with something trivially
simple myself that seemed to do the job. In fact, then and now, I'd
ignored the obvious: simply invert one of the inputs and use a vanilla
RC differentiator on each.

This was the circuit I used then.
http://www.terrypin.dial.pipex.com/Images/CurtainTimerAddOn.gif

I'm pretty sure that was what I implemented, and the gadget has been
working OK in the 16 months or so since.

The key difference *this* time is that I hope to feed these +ve pulses
(or squared up versions of them) not to a 4001 bistable but to a 4013,
as mentioned.

I haven't got around to that stage yet, so would welcome any feedback
- especially if my idea is a non-starter. I want the 4013 to achieve
the following 3 things:

1. +ve pulse A to Set pin 8 always sets or keeps 4013 output high.

2. +ve pulse B to Reset pin 10 always resets or keeps 4013 output low.

3. A +ve pulse T (from another source) to Clock pin 3 always toggles
the 4013 output.

For background, the practical application is a garden lights
controller for my son. At present the lights have an on/off switch
inconveniently located in his shed/garage at the bottom of the rear
garden. My unit should
- Switch (or keep) the lights on at dusk
- Switch (or keep) the lights off at dawn
- Toggle the lights on or off at any time from a radio signal from the
house, improvised from a wireless doorbell adapter.
 
Terry said:
Thanks guys, much appreciate all the replies. Some neat ideas to
follow up there.

But even while composing my OP it was nagging away at me that I'd
asked essentially the same question before. Further digging this
morning turned it up:
Subject: 2 pulses from 1
Date: Mon, 28 Feb 2005

Premature senility aside, I'm guessing that the reason it had slipped
my mind was that, although I had two great solutions from Fred Bartoli
and Fred Bloggs, I'd managed to come up with something trivially
simple myself that seemed to do the job. In fact, then and now, I'd
ignored the obvious: simply invert one of the inputs and use a vanilla
RC differentiator on each.

This was the circuit I used then.
http://www.terrypin.dial.pipex.com/Images/CurtainTimerAddOn.gif

I'm pretty sure that was what I implemented, and the gadget has been
working OK in the 16 months or so since.

The key difference *this* time is that I hope to feed these +ve pulses
(or squared up versions of them) not to a 4001 bistable but to a 4013,
as mentioned.

I haven't got around to that stage yet, so would welcome any feedback
- especially if my idea is a non-starter. I want the 4013 to achieve
the following 3 things:

1. +ve pulse A to Set pin 8 always sets or keeps 4013 output high.

2. +ve pulse B to Reset pin 10 always resets or keeps 4013 output low.

3. A +ve pulse T (from another source) to Clock pin 3 always toggles
the 4013 output.

For background, the practical application is a garden lights
controller for my son. At present the lights have an on/off switch
inconveniently located in his shed/garage at the bottom of the rear
garden. My unit should
- Switch (or keep) the lights on at dusk
- Switch (or keep) the lights off at dawn
- Toggle the lights on or off at any time from a radio signal from the
house, improvised from a wireless doorbell adapter.


Um, if that's all that you want to do (turn the garden lights on at
night, and turn them off at sunrise), wouldn't a simple photocell do
the job? Something like this:

http://www.acehardware.com/product/...otocell&parentPage=search&searchId=5663252852

Good luck,

Michael
 
J

John Fields

Jan 1, 1970
0
I could not come up with an unambigious understanding of what he wants,
so I prefaced my reply with "If". I am still not sure what he wants.
 
T

Terry Pinnell

Jan 1, 1970
0
John Fields said:
On 24 Jun 2006 16:19:30 -0700, [email protected] wrote:

My take on it was that he wanted the rising edge of his input signal
to generate a spike which lasted for 10ms and was sent to the SET
input of his RS latch, and then, when his input signal went low, he
wanted that edge to generate a spike which would RESET his latch.

JF: Yep.

JP: I thought my carefully-worded opening sentence was clear enough:
"I have a long, clean positive pulse (hours in duration). How can I
get two *separate* 10 ms +ve pulses from the leading and trailing
edges."

--
Terry Pinnell
Hobbyist, West Sussex, UK



please?
 
A

amdx

Jan 1, 1970
0
Terry Pinnell said:
I have a long, clean positive pulse (hours in duration). How can I get
two *separate* 10 ms +ve pulses from the leading and trailing edges
please?

A simple RC differentiator (of appropriate polarity) would be the
obvious solution if I only wanted one or the other. But I can't figure
out how to get *both*, as separate signals.

FWIW, I want to take these pulses to the Set and Reset pins of a 4013.

Hi Terry,
I posted a simular question on 1-08-06 on this group.
Under the subject >Generating start and end pulse<
I put the circuit below together and it worked perfectly.
Many thanks to Ken Smith.
Sorry I don't recall component values, but an archive search
should find some values.
Mike

-----+----
! !
!/ !
GND ---! !
!\ e !
! !/
---!!--/\/\/--+--+---!
! !\ e
\ !
/ GND
\
!
GND
 
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