555

R

Roger Dewhurst

Guest
When a 555 is wired as a 1 Hz square wave oscillator and pin 4 goes high
does pin 3 go high at the same instant or does it go high half a cycle
later?

R
 
On Mon, 21 Sep 2009 13:52:45 +1200, Roger Dewhurst <dewhurst@wave.co.nz>
wrote:

When a 555 is wired as a 1 Hz square wave oscillator and pin 4 goes high
does pin 3 go high at the same instant or does it go high half a cycle
later?
Click to expand...
---
It goes high immediately.
 
Roger Dewhurst wrote:
When a 555 is wired as a 1 Hz square wave oscillator and pin 4 goes high
does pin 3 go high at the same instant or does it go high half a cycle
later?

R
Click to expand...
Pin 4 is usually held high. Are you reseting the thing
with pulses on pin 4 - or was that a typo?

Ed
 
Roger Dewhurst wrote:
When a 555 is wired as a 1 Hz square wave oscillator and pin 4 goes high
does pin 3 go high at the same instant or does it go high half a cycle
later?
Click to expand...
Bascially as John said.

If you go from a low to high transition on the reset pin, the output
will go high straight away. Has nothing to do with any duty cycle you
have set up.

Well, it will have a marginal delay, which will be shown in the data sheets.


Don...


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On Mon, 21 Sep 2009 13:52:45 +1200, Roger Dewhurst
<dewhurst@wave.co.nz> wrote:

When a 555 is wired as a 1 Hz square wave oscillator and pin 4 goes high
does pin 3 go high at the same instant or does it go high half a cycle
later?

R
Click to expand...
Pin 4 is the "reset," it is held high by being hard wired to Vcc for
astable operation, so this must be a trick question.

You should google for this real basic stuff before posting.

http://www.play-hookey.com/digital/timer_555.html

http://555-timer.clarkson-uk.com/

http://en.wikipedia.org/wiki/555_timer_IC

http://ece-www.colorado.edu/~ecen4618/lab1.pdf
--
 
ehsjr wrote:
Roger Dewhurst wrote:
When a 555 is wired as a 1 Hz square wave oscillator and pin 4 goes
high does pin 3 go high at the same instant or does it go high half a
cycle later?

R

Pin 4 is usually held high. Are you reseting the thing
with pulses on pin 4
Click to expand...
That is what I was thinking.

Two 555s with pin 3 of the first connecting to pin 4 of the second.

The first has a lower frequency that the second. The result should be a
short repeating series of pulses. Each series is separated by a
distinct pause.

I am sure that there are other ways of achieving this.

R


- or was that a typo?
Ed
Click to expand...
 
default wrote:
On Mon, 21 Sep 2009 13:52:45 +1200, Roger Dewhurst
dewhurst@wave.co.nz> wrote:

When a 555 is wired as a 1 Hz square wave oscillator and pin 4 goes high
does pin 3 go high at the same instant or does it go high half a cycle
later?

R

Pin 4 is the "reset," it is held high by being hard wired to Vcc for
astable operation, so this must be a trick question.
Click to expand...
No trick. See my reply to an earlier post.

R
You should google for this real basic stuff before posting.

http://www.play-hookey.com/digital/timer_555.html

http://555-timer.clarkson-uk.com/

http://en.wikipedia.org/wiki/555_timer_IC

http://ece-www.colorado.edu/~ecen4618/lab1.pdf
Click to expand...
 
John Fields wrote:
On Mon, 21 Sep 2009 13:52:45 +1200, Roger Dewhurst <dewhurst@wave.co.nz
wrote:

When a 555 is wired as a 1 Hz square wave oscillator and pin 4 goes high
does pin 3 go high at the same instant or does it go high half a cycle
later?

---
It goes high immediately.


Thank you for your no nonsense answer.
Click to expand...

R
 
On Tue, 22 Sep 2009 12:32:46 +1200, Roger Dewhurst <dewhurst@wave.co.nz>
wrote:

John Fields wrote:
On Mon, 21 Sep 2009 13:52:45 +1200, Roger Dewhurst <dewhurst@wave.co.nz
wrote:

When a 555 is wired as a 1 Hz square wave oscillator and pin 4 goes high
does pin 3 go high at the same instant or does it go high half a cycle
later?

---
It goes high immediately.


Thank you for your no nonsense answer.
Click to expand...
---
You're welcome. :)

BTW, in response to one of your other posts, here's how to do it using
logic gates:

Version 4
SHEET 1 1300 680
WIRE -112 -224 -272 -224
WIRE -80 -224 -112 -224
WIRE 32 -224 -16 -224
WIRE 240 -224 80 -224
WIRE 272 -224 240 -224
WIRE 384 -224 336 -224
WIRE -112 -192 -112 -224
WIRE 240 -192 240 -224
WIRE -272 -96 -272 -224
WIRE -224 -96 -272 -96
WIRE 80 -96 80 -224
WIRE 128 -96 80 -96
WIRE -112 -80 -112 -112
WIRE -112 -80 -160 -80
WIRE -96 -80 -112 -80
WIRE -64 -80 -96 -80
WIRE 32 -80 32 -224
WIRE 32 -80 0 -80
WIRE 240 -80 240 -112
WIRE 240 -80 192 -80
WIRE 256 -80 240 -80
WIRE 288 -80 256 -80
WIRE 384 -80 384 -224
WIRE 384 -80 352 -80
WIRE 448 -80 384 -80
WIRE -96 -48 -96 -80
WIRE -64 -48 -96 -48
WIRE 256 -48 256 -80
WIRE 288 -48 256 -48
WIRE -224 -32 -272 -32
WIRE 32 -32 32 -80
WIRE 128 -32 32 -32
WIRE -272 0 -272 -32
WIRE -272 128 -272 80
FLAG -272 128 0
SYMBOL cap 336 -240 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C1
SYMATTR Value 1e-7
SYMBOL res 256 -96 R180
WINDOW 0 36 76 Left 0
WINDOW 3 36 40 Left 0
SYMATTR InstName R1
SYMATTR Value 1e6
SYMBOL Digital\\and 160 0 M180
SYMATTR InstName A1
SYMATTR Value2 vhigh 5v trise 1e-6 tfall 1e-6
SYMBOL Digital\\and 320 0 M180
SYMATTR InstName A2
SYMATTR Value2 vhigh 5v trise 1e-7 tfall 1e-7
SYMBOL cap -16 -240 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C2
SYMATTR Value 1e-6
SYMBOL res -96 -96 R180
WINDOW 0 36 76 Left 0
WINDOW 3 36 40 Left 0
SYMATTR InstName R2
SYMATTR Value 1e6
SYMBOL Digital\\and -192 0 M180
SYMATTR InstName A3
SYMATTR Value2 vhigh 5v trise 1e-6 tfall 1e-6
SYMBOL Digital\\and -32 0 M180
SYMATTR InstName A4
SYMATTR Value2 vhigh 5v trise 1e-7 tfall 1e-7
SYMBOL voltage -272 -16 R0
WINDOW 3 24 104 Invisible 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 5
TEXT -264 104 Left 0 !.tran 10 uic
TEXT 448 -80 Left 0 ;> OUT
TEXT -224 -120 Left 0 ;HC02

JF
 
On Tue, 22 Sep 2009 12:30:36 +1200, Roger Dewhurst
<dewhurst@wave.co.nz> wrote:

No trick. See my reply to an earlier post.

R
Click to expand...
Oh. Usually my mind reading ability is much better. Sorry.
--
 
On Tue, 22 Sep 2009 07:38:08 -0500, John Fields
<jfields@austininstruments.com> wrote:

On Tue, 22 Sep 2009 12:32:46 +1200, Roger Dewhurst <dewhurst@wave.co.nz
wrote:

John Fields wrote:
On Mon, 21 Sep 2009 13:52:45 +1200, Roger Dewhurst <dewhurst@wave.co.nz
wrote:

When a 555 is wired as a 1 Hz square wave oscillator and pin 4 goes high
does pin 3 go high at the same instant or does it go high half a cycle
later?

---
It goes high immediately.


Thank you for your no nonsense answer.

---
You're welcome. :)

BTW, in response to one of your other posts, here's how to do it using
logic gates:

Version 4
SHEET 1 1300 680
WIRE -112 -224 -272 -224
WIRE -80 -224 -112 -224
WIRE 32 -224 -16 -224
WIRE 240 -224 80 -224
WIRE 272 -224 240 -224
WIRE 384 -224 336 -224
WIRE -112 -192 -112 -224
WIRE 240 -192 240 -224
WIRE -272 -96 -272 -224
WIRE -224 -96 -272 -96
WIRE 80 -96 80 -224
WIRE 128 -96 80 -96
WIRE -112 -80 -112 -112
WIRE -112 -80 -160 -80
WIRE -96 -80 -112 -80
WIRE -64 -80 -96 -80
WIRE 32 -80 32 -224
WIRE 32 -80 0 -80
WIRE 240 -80 240 -112
WIRE 240 -80 192 -80
WIRE 256 -80 240 -80
WIRE 288 -80 256 -80
WIRE 384 -80 384 -224
WIRE 384 -80 352 -80
WIRE 448 -80 384 -80
WIRE -96 -48 -96 -80
WIRE -64 -48 -96 -48
WIRE 256 -48 256 -80
WIRE 288 -48 256 -48
WIRE -224 -32 -272 -32
WIRE 32 -32 32 -80
WIRE 128 -32 32 -32
WIRE -272 0 -272 -32
WIRE -272 128 -272 80
FLAG -272 128 0
SYMBOL cap 336 -240 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C1
SYMATTR Value 1e-7
SYMBOL res 256 -96 R180
WINDOW 0 36 76 Left 0
WINDOW 3 36 40 Left 0
SYMATTR InstName R1
SYMATTR Value 1e6
SYMBOL Digital\\and 160 0 M180
SYMATTR InstName A1
SYMATTR Value2 vhigh 5v trise 1e-6 tfall 1e-6
SYMBOL Digital\\and 320 0 M180
SYMATTR InstName A2
SYMATTR Value2 vhigh 5v trise 1e-7 tfall 1e-7
SYMBOL cap -16 -240 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C2
SYMATTR Value 1e-6
SYMBOL res -96 -96 R180
WINDOW 0 36 76 Left 0
WINDOW 3 36 40 Left 0
SYMATTR InstName R2
SYMATTR Value 1e6
SYMBOL Digital\\and -192 0 M180
SYMATTR InstName A3
SYMATTR Value2 vhigh 5v trise 1e-6 tfall 1e-6
SYMBOL Digital\\and -32 0 M180
SYMATTR InstName A4
SYMATTR Value2 vhigh 5v trise 1e-7 tfall 1e-7
SYMBOL voltage -272 -16 R0
WINDOW 3 24 104 Invisible 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 5
TEXT -264 104 Left 0 !.tran 10 uic
TEXT 448 -80 Left 0 ;> OUT
TEXT -224 -120 Left 0 ;HC02
^^^^
Click to expand...
Aarghhh!!! .............HC00

JF
 
default wrote:
On Tue, 22 Sep 2009 12:30:36 +1200, Roger Dewhurst
dewhurst@wave.co.nz> wrote:

No trick. See my reply to an earlier post.

R

Oh. Usually my mind reading ability is much better. Sorry.
Click to expand...
Accepted. None of us can get through life without the occasional cockup.

R
 
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