Re: ic 555 timer small diagram needed

On Oct 3, 4:10 am, ehsjr <eh...@xxxxxxxxxxxxxxxxx> wrote:
ehsjr wrote:
porkys...@xxxxxxxxxxx wrote:

On Oct 1, 1:02 am, ehsjr <eh...@xxxxxxxxxxxxxxxxx> wrote:

porkys...@xxxxxxxxxxx wrote:

right what i need is a diagram for the conditions i need... let me
explain

i need to press and release a NO switch and after certain time like
say 15 mins i need it to engage a relay for say 5 mins then disengage
the relay and wait for the push button again after.
**i could go as far as opto-isolation as it doesnt need much current
for switching but it does need seperation

many thanks
Ian

ps i seen many diagrams with this tan and other but there talking
beyond what need to know.. i got a strong guess i need 2x555 and
perhaps what they call a "flip flop" circuit unless anyone has a
better idea?

Getting 15 minutes from a 555 reliably is tough. Instead,
set the 555 to run astable at ~2.5 minutes, and use its
output as the clock for a 4017.

Diode or all of the 4017 outputs except count 9 to the base
of an NPN and a 1K. An example of the "diode or" is best seen
in the second partial schematic below. The schematics are
representative of what you need to do, not complete. The N/O
switch also connects to the commoned cathodes of the diodes.
The NPN controls power to the circuit. Pressing the button
turns the NPN on, and the 4017 keeps it turned on until the
count reaches 9, in ~ 20 minutes. Diode or counts 7 and 8
to another NPN through a 1K - that transistor can control a
relay to give you you a ~ 5 minute output.

NPN
+12 ---+---+ +------- Vcc to 555 and 4017 and relay
| c\ /e
| ---
| |
| [1K]
| | Dx
+-o o-+------|<---Counts 0-8 from 4017,
N/O | each count thru its own
| diode (Dx)
[33K]
|
Gnd ---------+

The 33K ensures the transistor turns off when the 4017
is not counting from 0 through 8.

For your 5 minute output:

+Vcc ----+
|
[Relay]
| +---|<---Count 8 from 4017
\c |
NPN |---[1K]---+---|<---Count 7 from 4017
/e |
| |
Gnd -----+----[33K]---+

The relay needs a diode across it with the cathode
connected on the + side.

Ed

Right, so basically I connect to the npn transistor by diodes (or
leds?) with pins 1, 2, 3, 4, 7 and 10

Yes those are the correct pins, but you need to add
more pins - pin 9 and pin 10. That will give you
counts 0,1,2,3,4,5,6,7, and 8. Each count stays
active for 2.5 seconds, so the timing cycle is
2.5 * 8 = 20 seconds. Each output (count) goes +
for 2.5 seconds. The output is connected through
a diode, and the cathodes of t6he diodes are connected
together. The base of the NPN is connected to the cathodes
through a 1K resistor.

Groan - you wanted 2.5 minutes, not seconds. Change the
word seconds to minutes above. Correction to the 555
components appears below. Also, I added 1 pin too
many. You want counts 0,1,2,3,4,5,6 and 7, so you need
to add pin 10 (not pins 9 and 10 - do not add pin 9).



The collector of that NPN is connected to the plus
side of whatever power supply you are using. The power
supply needs to be between 5 and 15 volts. The emitter
of that NPN provides power for the 4017, the 555 and the
relay.

and use pins 5and 6 connected to

No, use pins 6 and 9.

^^^ ^^ ^^
Yes, use pins 5 and 6



They are connected to 2 more diodes.
Those two diodes als have their cathodes connected to a 1K
resistor, and the other side of that 1K resistor is connected
to the base of another NPN transistor. No opto isolator is
needed or used.

the npn and opto-isolation device instead for switching another npn
for a relay. It�s the same as a diode but using less power than the
relay, so I figured that out its now the 555 timer connection and
circuit to the cmos chip.

The tech *** I was looking at started from output 0, this means
pins 9 and 11 don�t use (just incase someone else finds this useful)

You will use pin 9, but you won't use pin 11

right the 555 pinout?
1,is gnd
2, E from npn
3, connect to hi-low on cmos
4,dont use
5,dont use
6, connect to ground?
7, connect c+r to 1
8, V+

please can you confirm I have this correct

No - see below.

Questions.
What do the diodes and the switch connect to on the npn,

The base of the NPN, through a 1K resistor.

I really need
a better drawing.
I did see on the tech *** of the cmos chip it sounds like that the
output pins give out different power or something as it suggests that
only certain pins to be used to time another decade counter cmos chip,
is this right if so do I still use diode to the npn?

For a diagram of the 555, see this url:
http://www.doctronics.co.uk/555.htm#astable

You will select R1, R2 and C to set the timing for
~ 2.5 seconds. Start with R1 = 33K and use a 50K
pot for R2. For C, use a 33 uF electrolytic.
You can adjust the pot to "fine tune" the 2.5
second pulses that the 555 will produce.

Aaargh! I figured the timing components for the 555
based on seconds, not minutes. Change R1 to 330K,
R2 to a 500K pot, and C to a 220 uf cap to get 2.5
_minute_ timing.

Ed



You can also find a diagram of the 4017 at
http://www.doctronics.co.uk/4017.htm

Connect the output (pin 3) of the 555 to the clock input
of the 4017 through a 1K resistor.

If this is not clear, I can email a jpg schematic
to you.

Ed

lol i fell asleep sending an email again... didnt see your latest post
but the latest mail has an interesting section that the last 2 output
pins still need to be connected to the first npn otherwise the 555 and
4017 will power down.. thus i think it also needs to be connected to
another diode to the npn
to stop power coming back from the other outputs and still allow the
latter 2 to send power to both... i really need to get a breadboard
and the components..

thanks for the better pictures and diagrams in the links that helped
loads! im just awake at 14:30 ahh i got work soon :/ well catch you
later like erm 3 am? UK time :D
.

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