Re: Help - timing and switching circuit needed

Steve Newport wrote:
On Tue, 03 Apr 2007 04:50:17 GMT, ehsjr <ehsjr@xxxxxxxxxxxxxxxx>
wrote:


Steve Newport wrote:

On Thu, 29 Mar 2007 10:13:33 -0700, Donald <Donald@xxxxxxxxxxxxxxxx>
wrote:



Steve Newport wrote:



Steve Newport wrote:



Hello all,

I am trying to find out how to build (sorry am a relative amature) a
timing and switching circuit. The basics are as follows:

Operates off a 12v dc battery
operates (single pulse) up to eight 12v dc solenoids. sequence of operation is set
timing between each operation could vary in the range 12-48 hours

Can anybody help?

Do you mean that solenoid 1 operates, then 12-48 hours
later solenoid 2 operates, then 12-48 hours later
solenoid 3 operates, etc?

Ed

Yep, a couple of places in the sequence more than one solenoid may
operate but essentialy yes.


Ok, a long duration sequencer.

What is the "single pulse" ??

Any microcontroller chip with a RTC (real time clock) chip and a relay driver chip can do this.

Are you looking at "building this yourself" by,

a) buying computer/logic boards and programming them yourself.
b) building your computer/logic PCBs and soldering the chips down yourself then programming them.
or
c) buying a complete system that can control relays with a "single pulse"

How much of "build it" are you interested in doing ??

donald


Sorry, the description I gave was a bit wooly. The solenoid acts to
open a small catch - all it needs is one pulse to make it pull. ie: No
need for a permanent current to be applied. Hope that makes sense.

Was hoping to do a complete self build but if there is something ready
made then why re0invent the wheel so to speak?

Was hpong that what I need would be some combination of a 555 chip and
relay etc. Wasn't imagining anything like programming as that would
probably be quite beyon my capabilities.

I could cope (just) with buying components and soldering them together
:-(


There's a kit than can be set up to give you a pulse
every ~22 hours (or less).
http://store.qkits.com/moreinfo.cfm/QK152
You would need to add two circuits: a 4017 counter to
advance to the next solenoid when the kit provides a
pulse, and a solenoid driver circuit that will provide
a pulse to the solenoid. We need to know a couple of
things. How long does the pulse to the solenoid have
to be, at a minimum? How much current does the solenoid
take? Can you build the two additional circuits without
using a kit?

Ed


Thanks Ed. The solenoid I was looking to use can be seen at
http://www.islikersolenoids.co.uk/scripts/isliker/linear_type5.html

Not suggesting you look it up - just wanted to state it in case you
wanted to look. I have downloaded the technical data *** but it
doesn't seem to give the details so I have emailed the company and
asked. I'll post back when I get a reply.

I understand what you have suggested (many thanks indeed) and it makes
sense. Whilst I am probably OK with the solenoid driver circuit; the
technical data *** I downloaded gives me some examples and they seem
straight forward. However, the 4017 counter - I wouldn't know where to
start. Is it likely that a kit is available?


There is a kit CAT# AEC at Allelectronics
http://www.allelectronics.com/

It is an LED chaser kit - you would need to modify
it (simple - don't install the 555). As designed, a
555 runs as an astable. The output of the 555 clocks
the 4017 counter - the output of the counter drives
the LEDs. You would use the QK152 output to create
the clock pulse that advances the 4017 counter.
Connect teh QK152 output to pin 14 of the 4017.
You would also need to modify the QK152 to reset
itself when it reached the period you select so that
it starts timing all over again. (Mod described
below)

Here's how you could do it:
In the QK152 when the 4020 counter reaches a value of 8,
use that pulse to activate the solenoid driver. When the
count reaches the value equal to your period, use that
pulse to advance the 4017. The same pulse is used to
reset the 4020 to 0 (connect the reset pin, pin 11, to
the pin for the period you chose). The 4017 count is used
to energize a relay or bias a transistor on so that when
the solenoid driver pulse arrives ~ 8 seconds later, the
correct solenoid is fired.

QK152 mod: you need to connect pin 4 of the 555 to
pin 8 of the 555, and remove the connection from pin
4 of the 555 to the collector of Q1. The collector
of Q1 needs to remain connected to R7 if you wish
to use the transistor outputs for something. As mentioned
above, you need to connect the period output pin to
tyhe reset pin to set the 4020 to 0.

Ed
.