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556 dual timer problem

I

Ian Bell

Jan 1, 1970
0
I have used a 556 dual timer to build a motorbike indicator lights
flasher for a friend. The first timer is arranged as a 30 second one
shot which enables the second timer which is arranged as a 1 sec astable
to flash the indicators. When the first timer is triggered, the second
operates for about 30 secs - the circuit is straight out of the
applications section of the data sheet. I have built two identical
circuits, one for the left and one for the right indicators and operated
by a SPDT momentary switch.

There is one problem though. When it is first powered up, the one shot
timers trigger and both the indicators flash for the 30 second interval.
After that it functions as normal. When first starting up this is a
minor inconvenience but if he stalls the bike and restarts then it
happens again and as he says 'is a bloody pain in the ass'.

So, is there a way to ensure the 30 second one shots do not trigger at
power up?


Cheers

Ian
 
I

Ian Bell

Jan 1, 1970
0
Jan said:
Sure, use a PIC.
LOL
1 PIC, for everything.

I had thought of that originally but I would need to by a development
board and learn to program it. A 556 design was quicker and cheaper. As
I have made and built a PCB for my friend I am hoping a simple fix is
available. If not, then I will PIC it.

Cheers

Ian
 
T

Tim Williams

Jan 1, 1970
0
Switch the trig and threshold pins, and the polarity used to drive them. Or
it may be as simple as changing which supply rail the trigger cap is
referenced to.

Tim
 
A

amdx

Jan 1, 1970
0
Ian Bell said:
I have used a 556 dual timer to build a motorbike indicator lights flasher
for a friend. The first timer is arranged as a 30 second one shot which
enables the second timer which is arranged as a 1 sec astable to flash the
indicators. When the first timer is triggered, the second operates for
about 30 secs - the circuit is straight out of the applications section of
the data sheet. I have built two identical circuits, one for the left and
one for the right indicators and operated by a SPDT momentary switch.

There is one problem though. When it is first powered up, the one shot
timers trigger and both the indicators flash for the 30 second interval.
After that it functions as normal. When first starting up this is a minor
inconvenience but if he stalls the bike and restarts then it happens again
and as he says 'is a bloody pain in the ass'.

So, is there a way to ensure the 30 second one shots do not trigger at
power up?


Cheers

Ian

Just a guess without seeing your circuit, try slowing the Vcc rise until
the trigger
input has risen. Or hold trigger high untill Vcc is stable.
Can you post your circuit?
Mike
 
S

Shaun

Jan 1, 1970
0
Ian Bell said:
I have used a 556 dual timer to build a motorbike indicator lights flasher
for a friend. The first timer is arranged as a 30 second one shot which
enables the second timer which is arranged as a 1 sec astable to flash the
indicators. When the first timer is triggered, the second operates for
about 30 secs - the circuit is straight out of the applications section of
the data sheet. I have built two identical circuits, one for the left and
one for the right indicators and operated by a SPDT momentary switch.

There is one problem though. When it is first powered up, the one shot
timers trigger and both the indicators flash for the 30 second interval.
After that it functions as normal. When first starting up this is a minor
inconvenience but if he stalls the bike and restarts then it happens again
and as he says 'is a bloody pain in the ass'.

So, is there a way to ensure the 30 second one shots do not trigger at
power up?


Cheers

Ian

A solution would be to put an Resistor + capacitor from Vcc to GND , the
capacitor on the lower half and the midpoint to the RESET pin(s) of the 556.
That way there is a small time delay before the RESET line goes high.

Shaun
 
R

Rich Grise

Jan 1, 1970
0
Sure, use a PIC.
LOL
1 PIC, for everything.

No "use a PIC" posts without a full schematic and code listing, as well as
an offer to use your own $150 development system to program the thing for
him.

Thanks,
Rich
 
R

Rich Grise

Jan 1, 1970
0
I have used a 556 dual timer to build a motorbike indicator lights flasher
for a friend. The first timer is arranged as a 30 second one shot which
enables the second timer which is arranged as a 1 sec astable to flash the
indicators. When the first timer is triggered, the second operates for
about 30 secs - the circuit is straight out of the applications section of
the data sheet. I have built two identical circuits, one for the left and
one for the right indicators and operated by a SPDT momentary switch.

There is one problem though. When it is first powered up, the one shot
timers trigger and both the indicators flash for the 30 second interval.
After that it functions as normal. When first starting up this is a minor
inconvenience but if he stalls the bike and restarts then it happens again
and as he says 'is a bloody pain in the ass'.

So, is there a way to ensure the 30 second one shots do not trigger at
power up?
A 10 uF or so cap from the reset input (pin 4 or 10, whichever) to ground,
with, say, a 47K resistor to +.

This is a very easy hack; try it and report back, OK?

Good Luck!
Rich
 
R

Rich Grise

Jan 1, 1970
0
On a sunny day (Fri, 04 Dec 2009 09:39:27 -0800) it happened Rich Grise


Look, dude, I could have written 'micro'. You will have to face the fact
that lots of analog stuff can be done much easier in a PIC or some other,
possibly less easy to obtain, less easy to program, with a more
complicated instruction set, less reliable, more power hungry OTHER micro.

Oh, don't take yourself so damn seriously. ;-)

Cheers!
Rich
 
R

Rich Grise

Jan 1, 1970
0
On a sunny day (Fri, 04 Dec 2009 12:10:32 -0800) it happened Rich Grise

Oh, well, I was just trying to help ;-)

I wonder - is there a version where I can write the program in, say, C or
BASIC, and upload it to the chip with nothing more than a breadboard and
serial port? (i.e., no $150.00 dev. kit?)

Thanks,
Rich
 
I

Ian Bell

Jan 1, 1970
0
Rich said:
A 10 uF or so cap from the reset input (pin 4 or 10, whichever) to ground,
with, say, a 47K resistor to +.

This is a very easy hack; try it and report back, OK?

Good Luck!
Rich

Thanks Rich; a couple of people have now mentioned that mod - reset is
tied directly to Vcc right now so holding it low until things have
settled down seems like a good solution. I'll get the PCB back from my
friend and try it out.

Cheers

Ian
 
T

Tim Williams

Jan 1, 1970
0
Jan Panteltje said:
I get:
Flash Player 9 or later required to view this video.
Please visit Adobe to get the latest version of the Flash Player.

I think this is a bad site, as I do have flash, too many popups too.

Well, duh it needs flash. I don't even know of video sites offhand that
don't use Flash or Javascript in some fashion. Youtube, Google Video,
Metacafe, etc.

http://xkcd.com/619/

As for popups, there are none. There are ads, since they need income.

Tim
 
H

Hammy

Jan 1, 1970
0
I wonder - is there a version where I can write the program in, say, C or
BASIC, and upload it to the chip with nothing more than a breadboard and
serial port? (i.e., no $150.00 dev. kit?)

Thanks,
Rich

You dont need a $150.00 dev. kit all you need is a PICKIT2 or 3 usb
programer . $50.00 if you search around you could probably find it
cheaper.Microchip supplies free C and asm compilier.

It would take him maybe a day to figure out how to program his 556
circuit.

http://canada.newark.com/microchip/dv164120/development-tools-pickit-2-starter/dp/44K0230
 
R

Rich Grise

Jan 1, 1970
0
On a sunny day (Fri, 04 Dec 2009 14:18:27 -0800) it happened Rich Grise
...
But you need to understand the basics of microprocessors, and programming.

No worries here - I've been programming micros since there have been
micros. (my first computer course was on the Control Data (Bendix) G-15:
http://members.iinet.net.au/~dgreen/docs.html
in about 1966. :)

The problem I have with the PIC is bank switching, which I consider evil.
;-) I was thinking about a HLL because the compiler "should" handle all
that.

Or is there a version of the PIC that does all the above _without_
any bank switching?

Thanks,
Rich
 
R

Rich Grise

Jan 1, 1970
0
No.

Real men use COPY CON MYPROG.ARJ

"ARJ?"

These are two different animals - which language vs. editor or not.

e.g., copy con myprog.c, copy con myprog.asm, copy con myprog.bas,
etc.

What's "ARJ?"

Thanks,
Rich
 
A

amdx

Jan 1, 1970
0
Rich Grise said:
No worries here - I've been programming micros since there have been
micros. (my first computer course was on the Control Data (Bendix) G-15:
http://members.iinet.net.au/~dgreen/docs.html
in about 1966. :)

The problem I have with the PIC is bank switching, which I consider evil.
;-) I was thinking about a HLL because the compiler "should" handle all
that.

Or is there a version of the PIC that does all the above _without_
any bank switching?

Thanks,
Rich
I might have to bank switch and PIC a new bank.
A report about my bank;
"The bank's board of directors received an order from the Office of Thrift
Supervision last Friday.
The order followed an August notification that THE BANK was significantly
under-capitalized. The bank responded with a Capital Restoration Plan in
October, but it was rejected by federal regulators." (Dec 4)
 
B

Baron

Jan 1, 1970
0
Rich said:
"ARJ?"

These are two different animals - which language vs. editor or not.

e.g., copy con myprog.c, copy con myprog.asm, copy con myprog.bas,
etc.

What's "ARJ?"

Thanks,
Rich

An archive prog... Like "ZIP" or "ARC" !
 
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