556 dual timer problem

[Ian Bell]

No, in the states, but postage is not that much different.

OK, I have bought tubes from the US and postage was $15 or less, so how
much do you want for it?

Cheers

Ian

 

[krw]

Well, if you follow that concept to its logical conclusion, you should
buy ammunition, not gold.

Got ya' covered. ;-)

 

[JosephKK]

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

Think carefully about the device and its properties. A cap or two
should solve this. And maybe a resistor; depending on the topology of
the existing circuit.

 

[JosephKK]

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

Cheers!
Rich

PKB

 

[JosephKK]

Real man write asm.
For something as simple as that .. just a few lines asm.
Hey it is only 35 or so instructions...
Read datasheets, your first take with any micro is learning about the hardware in it,
interrupt system, memory organisation, initialisation requirements...
But for the second project you can probably (if you worked in a clean way) re-use much of the code.
PICs are programed via a 3 wire system.
noppp programmer connects to some of the par port pins.
I wrote Linux soft for that circuit to program several PIC types.
Others did the same.
Code for noppp available upon request.
And if anybody complains about timing, IIRC I used the PC timer,
so it should work on any PC with a parport, 3$ part counts.

But you need to understand the basics of microprocessors, and programming.
That may take a while, and probably a lifetime to keep up.
And there are a thousand if not more solutions to the same problem possible.
All software, interrupts, hardware timers in the micro, it all up to you.
Plenty of example code on the Microchip site.
They also have a free C compiler and some cheap PIC programmer.
But for some flashing light? C? BASIC? Where is the world going?
hehe

Hey, i can buy nice dev kit for about $150; that is like an hour or so
of chargeable time. I work equally well in asm, C or basic. And once
you do asm startup code; asm is often is an easy as C or basic or any
other language.

 

[krw]

They are wearing out the ones they got!

But the Fed doesn't have *any* printing presses. ;-)

 

[JosephKK]

They are wearing out the ones they got!

How do you get that. Most money is electronic anyway.

 

[Rich Grise]

They are wearing out the ones they got!

But the Fed doesn't have *any* printing presses. ;-)[/QUOTE]

OK, then, under whose jurisdiction is the Bureau of Printing and Engraving?

OK, OK, it's not the Federal Reserve Bank, but it's still under the
purview of the Fed. Gov't. ;-)

Cheers!
Rich

 

[krw]

OK, then, under whose jurisdiction is the Bureau of Printing and Engraving?
Treasury.

OK, OK, it's not the Federal Reserve Bank, but it's still under the
purview of the Fed. Gov't. ;-)

In theory, not so much. The Fed certainly doesn't report to Treasury.
Money >> paper+ink

 

[Rich Grise]

..then where are those "extra" twenty (or so) trillion dollars coming
from?

I wonder what China is going to do when they figure out that the dollars
they're being paid back with are worth only half what the dollars they
lent were worth?

Thanks,
Rich

 

[Rich Grise]

That's alright. Half the shit they've sold us wasn't worth anything
either.

I was kinda talking about the $37 trillion deficit.

Thanks,
Rich

 

[krw]

Would be much better if a bunch of drunken sailors were running the
government...

Either way, we're going to have a whopping hangover.

 

[krw]

..then where are those "extra" twenty (or so) trillion dollars coming from?

They aren't being printed. It doesn't take a printing press to make
bits.

 

[krw]

I wonder what China is going to do when they figure out that the dollars
they're being paid back with are worth only half what the dollars they
lent were worth?

That's alright. Half the shit they've sold us wasn't worth anything
either.

 

[krw]

I was kinda talking about the $37 trillion deficit.

China's got little to do with that. They've pretty much financed the
stuff they've sold us (balanced the balance of trade with loans, give
or take).

 

[Jamie]

I wonder what China is going to do when they figure out that the dollars
they're being paid back with are worth only half what the dollars they
lent were worth?

Thanks,
Rich

I'm sure they have already figured that out. Most likely products
currently made, have their obsolescent / defect alarm calendar set back
to a much sooner date!

People, can we say, BAD CAPS, once again!

Good for the business!

 

[Ian Bell]

Several people have suggested using a PIC. One reason I chose the 556
timer is its wide supply voltage range. In this case, the motorcycle
battery voltage is just 6V and the 556 can be operated directly from it.
Looking at the data sheets, it seems typical PICS will work only up to
5.5V so I am going to need a regulator of some sort too. I get the
impression PICs work OK down to 3V or so, so a cheap 3.3V regulator
would probably do it, yes?

Cheers

Ian

 

[Rich Grise]

Several people have suggested using a PIC. One reason I chose the 556
timer is its wide supply voltage range. In this case, the motorcycle
battery voltage is just 6V and the 556 can be operated directly from it.
Looking at the data sheets, it seems typical PICS will work only up to
5.5V so I am going to need a regulator of some sort too. I get the
impression PICs work OK down to 3V or so, so a cheap 3.3V regulator would
probably do it, yes?

There's no problem with the 556, but be sure to filter the hell out of the
battery voltage!

Use an LC filter rather than RC, or maybe an R and an L in series, befor
the cap(s).

Cheers!
Rich

 

[Rich Grise]

It is very dagnerous to run _any_ micro directly fro ma car or motorcycle
battery. All sort of spikes may happen ,and a much higher voltage then 6
(in this case) can exists during charging. Your 556 or PIC will die.
maybe the simplest is a 4.7V zener, with a tantalum cap of about 10uF
parallel.

+6V -- R1 ----------------------------
| |
| === 10uF
4.7 V zener ---
| |
GND ----------------------------------

As 'PIC' uses no current to speak of, R 1 can be selected to limit current
in case of a high voltage on the input. Of course other parts of teh
cicuit can use some current, but a few hundred Ohm will limit surges, if
the max I i nteh zener for it to stay below 5.5V to protect the circuit
behind it is say 100mA, then, if your battery surges to 20 V yo uhave
aboyut 15 V over R1, at 100mA makes

I'd use a transzorb instead of a zener - they're designed to absorb spikes;
use one that's rated at about 7 or 8 V. I'd also use an inductor either
instead of the R1 there, or in series with it.

I know about transzorbs - at one company where I worked, they had MOVs all
over the place, and the service folks were continually going out to
replace them, or they'd ship the box to us for warranty repair. Then one
day, we discovered TransZorbs, and they worked so well that they issued
an ECO (Engr. Change Order) _and_ an EMO (Engr. Mod. Order) to get rid
of ALL the MOVs.

With just a zener, I'd see if there are any 5W zeners anywhere. Automotve
(and bike) electrical systems are extremely harsh.

Cheers!
Rich

 

[JosephKK]

..then where are those "extra" twenty (or so) trillion dollars coming from?

Somebody enters it at a keyboard and poof all your money is devalued.