timing circuits hel please

A

Andrew Bishop

Guest
I need a control circuit to control 3 relays

this is what I won't to happen a push to make switch is closed

relay 1 closes

time delay 0 - 5 seconds
relay 2 and 3 close

the push to make switch is closed for a length of time and released
(this is a manual operation)
on release

relay 2 opens
time delay 0 - .5 second
relay 3 opens

and relay 1 opens 0- 5 seconds after the the switch is released

all the time delays must be ajustable

can anyone point me in the right direction
I dont think that I can use a 555 timer for this one

Thanks Andrew
 
On Mon, 10 Aug 2009 12:15:21 -0700 (PDT), Andrew Bishop
<andrew@andrewbishop66.plus.com> wrote:

I need a control circuit to control 3 relays

this is what I won't to happen a push to make switch is closed

relay 1 closes

time delay 0 - 5 seconds
relay 2 and 3 close

the push to make switch is closed for a length of time and released
(this is a manual operation)
on release

relay 2 opens
time delay 0 - .5 second
relay 3 opens

and relay 1 opens 0- 5 seconds after the the switch is released

all the time delays must be ajustable
Click to expand...
A microcontroller with at least three ADs for the adjustment pots, one
digital input for the switch, three digital outputs for the relay
controls, plus the necessary transistors, diodes, resistors, and caps to
decorate the whole assemblage. If an internal RC oscillator would be
accurate enough, you'd not even need a crystal or clock for the thing.

can anyone point me in the right direction
I dont think that I can use a 555 timer for this one
Click to expand...
Not a single 555, certainly. Could probably wizard-up something with
multiple 555s but that seems unnecessarily painful, rather like walking
up stairs on one's hands.

Also: I assume that if the switch is released before the initial time
delay completes, the entire cycle is discarded and must begin anew.
However what happens, for example, if the switch is released after
relays 2 and 3 have shut but then the switch is closed again before
relay 3 has opened?

--
Rich Webb Norfolk, VA
 
On Aug 10, 8:38 pm, Rich Webb <bbew...@mapson.nozirev.ten> wrote:
On Mon, 10 Aug 2009 12:15:21 -0700 (PDT), Andrew Bishop



and...@andrewbishop66.plus.com> wrote:
I need a control circuit to control 3 relays

this is what I won't to happen a push to make switch is closed

relay 1 closes

time delay  0 - 5 seconds
relay 2 and 3 close

the push to make switch is closed for a length of time and released
(this is a manual operation)
on release

relay 2 opens
time delay  0 - .5 second
relay 3 opens

and relay 1 opens 0- 5 seconds  after the the switch is released

all the time delays must be ajustable

A microcontroller with at least three ADs for the adjustment pots, one
digital input for the switch, three digital outputs for the relay
controls, plus the necessary transistors, diodes, resistors, and caps to
decorate the whole assemblage. If an internal RC oscillator would be
accurate enough, you'd not even need a crystal or clock for the thing.

can anyone point me in the right direction
I dont think that I can use a 555 timer for  this one

Not a single 555, certainly. Could probably wizard-up something with
multiple 555s but that seems unnecessarily painful, rather like walking
up stairs on one's hands.

Also: I assume that if the switch is released before the initial time
delay completes, the entire cycle is discarded and must begin anew.
However what happens, for example, if the switch is released after
relays 2 and 3 have shut but then the switch is closed again before
relay 3 has opened?

--
Rich Webb     Norfolk, VA
Click to expand...
that wont cause a problem its to improve control on a welder
relay 1 is gas relay 2 is main power on no 3 is wire feed

I would most likely use a relay to start the circuit ie it would be
activated by the press switch

thanks Andrew
 
Andrew Bishop wrote:
I need a control circuit to control 3 relays

this is what I won't to happen a push to make switch is closed

relay 1 closes

time delay 0 - 5 seconds
relay 2 and 3 close

the push to make switch is closed for a length of time and released
(this is a manual operation)
on release

relay 2 opens
time delay 0 - .5 second
relay 3 opens

and relay 1 opens 0- 5 seconds after the the switch is released

all the time delays must be ajustable

can anyone point me in the right direction
I dont think that I can use a 555 timer for this one

Thanks Andrew
Click to expand...
The basic circuit you can use for Rly1 & Rly3, if timing need not
be precise, is below:

+12 ----+--------------+------+
| k| |
| [D1] [Rly1]
| | |
| +------+
| |
| A /c
+--o o---+---[1K]---| NPN darlington
| \e
+----+ |
| | |
[C1] [POT] |
| | |
Gnd -------------+----+-------+

Rly1 will energize immediately when the button is pressed,
and will stay energized as long as it is depressed. When
you release it, the relay will stay energized while C1
discharges. The pot (configured as a variable resistor) can
be adjusted for the required off delay. That takes care
of the on and off requirements for Rly1.

The same circuit can be used to set the drop out time for
Rly3, with a smaller value for the cap, since the maximum
drop out time is .5 seconds for that relay. The contacts
of Rly2 replace the pushbutton in the diagram for the Rly3
circuit. That takes care of the on and off requirements
for Rly3.

Rly2 must drop out when the button is released, so it
is connected to the point marked A on the diagram. That
takes care of the Rly2 off requirement.

The on requirement for Rly2 is different - there must be an
adjustable delay from the time the button is pressed until
the relay energizes. Here's the diagram:

Point A ---+------+---[Rly2]---+
| | |
| +----|<------+
[POT] k |
| /c
+---[1K]---[Zd]---| NPN darlington
| k \e
[C2] |
| |
Gnd -------+-------------------+

Use a 5.6v zener diode. When the charge on C2 rises high
enough for the zener to conduct, the relay will energize,
providing your on time delay.

Good starting values for the caps are 220 uF for the Rly1
and Rly2 circuits, and 22 uF for the Rly3 circuit. The POTs
can be 50K. I say "starting values" because you may have
parts in your junk box that you can substitute, and the closer
the maximum time that the circuit provides to the requirement,
the better. You want the circuit to be adjustable to just
a bit greater than the maximum requirement.

For selecting values of the capacitors and pots, you can use
the RC time constant to get in the ball park. A capacitor
charges to about 2/3 of Vcc in one time constant, or
discharges to about 1/3 Vcc in one time constant.
Tc (time constant) = R*C

Ed
 
"Andrew Bishop" <andrew@andrewbishop66.plus.com> schreef in bericht
news:c037c632-f05e-48f9-aa67-b24350d05fcc@b15g2000yqd.googlegroups.com...
On Aug 10, 8:38 pm, Rich Webb <bbew...@mapson.nozirev.ten> wrote:
On Mon, 10 Aug 2009 12:15:21 -0700 (PDT), Andrew Bishop



and...@andrewbishop66.plus.com> wrote:
I need a control circuit to control 3 relays

this is what I won't to happen a push to make switch is closed

relay 1 closes

time delay 0 - 5 seconds
relay 2 and 3 close

the push to make switch is closed for a length of time and released
(this is a manual operation)
on release

relay 2 opens
time delay 0 - .5 second
relay 3 opens

and relay 1 opens 0- 5 seconds after the the switch is released

all the time delays must be ajustable

A microcontroller with at least three ADs for the adjustment pots, one
digital input for the switch, three digital outputs for the relay
controls, plus the necessary transistors, diodes, resistors, and caps to
decorate the whole assemblage. If an internal RC oscillator would be
accurate enough, you'd not even need a crystal or clock for the thing.

can anyone point me in the right direction
I dont think that I can use a 555 timer for this one

Not a single 555, certainly. Could probably wizard-up something with
multiple 555s but that seems unnecessarily painful, rather like walking
up stairs on one's hands.

Also: I assume that if the switch is released before the initial time
delay completes, the entire cycle is discarded and must begin anew.
However what happens, for example, if the switch is released after
relays 2 and 3 have shut but then the switch is closed again before
relay 3 has opened?

--
Rich Webb Norfolk, VA
Click to expand...
|
| that wont cause a problem its to improve control on a welder
| relay 1 is gas relay 2 is main power on no 3 is wire feed
|
| I would most likely use a relay to start the circuit ie it would be
| activated by the press switch
|
| thanks Andrew
|

Reading this I think you'll need a professional PLC type of solution. It
sure can be done by electronics and a micro but you'll need experience to
complete a project like this without accidents.

petrus bitbyter
 
On Aug 10, 3:15 pm, Andrew Bishop <and...@andrewbishop66.plus.com>
wrote:
I need a control circuit to control 3 relays
( in a long sequence, up to 5 seconds, with adjustable time
Click to expand...
constants)

Instead of a '555, something which ramps UP when the switch
is closed, DOWN when it's released, will suffice.

So, it takes a single timing capacitor to do the ramping,
and a multiplicity of comparators (trim one input with a
potentiometer to change the timing) on the ramp signal
will trigger the various events, and the comparator output
transistor (presumably) suffices to drive the relays.
A set/reset flip flop or two can handle the up/down
timing asymmetry.

A quad comparator (LM339) and maybe some op amps,
regulated power supply, CMOS flip/flop, and it's done.
 
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