In need of some project assistance

[Bowman]

Hey there, i am new here so am not sure if this is the correct place to post this, plus i am typing this on a phone. So my project i have a problem with is this:

I wish to have a micro servo move 90° for ten seconds and then move back to its centre point after that duration and stay there until triggered again by a push-to-make button, the servo is to move a catch on my motorbikes rear storage box so it can be opened without the need to remove the key from the bike to open it, makes it more convenient and in a way a cool touch.

I have a Velleman PMK111'1 PCB interval timer as i was told it would be able to do exactly as i described but i have no clue how. There are no wiring instructions, only assembly instructions and I've already assembled the kit, so any help greatly appreciated as to how to wire it up if it will work fine or if i need some other board, i would rather have one board then several connected triggering each other as it would make reliability lower so the less separate circuits the better, plus got limited space as I'm on a bike and wish for it to be tidy.

So any information and ideas welcome

Thanks for reading!

 

[KeepItSimpleStupid]

You may have picked the wrong solution. I won't say that mine is the right one either, but if I had to do it, I'd consider a PICAXE. www.picaxe.com for the timing and control and an I2C or serial RC servo interface.

https://www.pololu.com/product/728

https://www.mindsensors.com/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=42

The ONLY reason for the RC controller is to remove an aspect of software development. A PICAXE and a robust 12 V to 5V power supply is more than enough to do the job by itself.

The mindsensors datasheet suggests that 2 power supplies are needed. One 5 V for logic and one 6 to 7.2 for the RC servo.

 

[Bowman]

Thanks for your response KeepItSimpleStupid, your opinions are greatly appreciated.

 

[Bowman]

Just want to note that i am in the UK and am trying to do this project with as little cost as possible and as simple as it can be, am probably just going to cut the controllers out of it and make it a stepper motor controlled by voltage if it comes to it.

 

[alec_t]

Unfortunately the kit timer is unsuitable for your project. As it stands it just switches a relay repeatedly on/off/on/off/.... at regular intervals. It could be modified to provide a single on/off cycle in response to a push-button press, but would still not provide the signal needed to drive a servo.
If no-one else jumps in with a ready-made solution I'll come up with something to do the necessary.

am probably just going to cut the controllers out of it and make it a stepper motor controlled by voltage

Driving a stepper motor is not just a matter of applying a voltage

 

[Bowman]

Thanks for your response alec_t, and i understand that its more than just applying voltage i was just saying it in basic terms.

 

[KeepItSimpleStupid]

Rotary solenoids https://www.alliedelec.com/search/results.aspx?term=70162392 are very strong, but cannot be engaged for very long without a special driver. Nice if you can find them surplus. This https://www.alliedelec.com/search/results.aspx?term=70162392 one is the wrong voltage.

 

[Bowman]

Probably a bit overkill for what i need it for KeepItSimpleStupid, and a bit pricey. Nice idea though much appreciated.

 

[4pyros]

Probably a bit overkill for what i need it for KeepItSimpleStupid, and a bit pricey. Nice idea though much appreciated.

How about a regular solenoid? If you get a 12 volt one all you would need is a switch to control it.
https://www.ebay.com/bhp/12v-pull-solenoid

 

[Bowman]

Ah that's a good idea using a regular solenoid, i could possably use the PCB i have to maybe make it so it stays open for 10 seconds when triggered and after moves back to its original place with the push-to-make button switch, i am wanting the button to be active when the ignition is on other wises anyone can open the box on the back if they knew what it was for and nick my stuff.

Would it be possible to wire the Velleman PMK 111'1 PCB to activate the solenoid like this? if so how would it be wired up?

 

[4pyros]

No the kit really is not good for your application. It does not have a trigger input and so the switch would have to be left on for the timer to work. Maybe it could be modified with a trigger input.

 

[KeepItSimpleStupid]

I like to throw out things even if they are silly. One thing we do not know is exactly how much force is needed. I am assuming the reason for the 10 seconds is not release time, but time to get back to the box.

A power door lock actuator for a car is a motorized rack with no limit switches that's activated for a short time. ebay had rotary solenoids cheap, not voltage listed. I wonder if a vacuum actuator will work? **broken link removed**

What I'm coming up with is either too big or too expensive.

Maybe a pic or some idea of the motion required. e.g. put a vertical weight and see what force is necessary without using a spring scale. But you could have a luggage scale handy.

 

[4pyros]

otary solenoids https://www.alliedelec.com/search/results.aspx?term=70162392 are very strong, but cannot be engaged for very long without a special driver. Nice if you can find them surplus. This https://www.alliedelec.com/search/results.aspx?term=70162392 one is the wrong voltage.

Probably a bit overkill for what i need it for KeepItSimpleStupid, and a bit pricey. Nice idea though much appreciated.

Jugging from this I think not much force is needed.

 

[KeepItSimpleStupid]

I did some more "thinking out loud" as I call it and this https://www.pololu.com/product/1350 might work for you. It's scriptable, cheap and uses a single automotive friendly supply.

And even the servos https://www.pololu.com/category/23/rc-servos are cheap.

I would like you to read this article: https://www.google.com/url?sa=t&rct...=pWk0NGrsPxd8a-MucDZjvw&bvm=bv.65788261,d.aWw

and read about this IC.

https://www.linear.com/product/LT4363

 

[4pyros]

I did some more "thinking out loud" as I call it and this https://www.pololu.com/product/1350 might work for you.

Thats cool but seems a bit over kill for one solenoid.

 

[KeepItSimpleStupid]

$20 USD is overrkill? What are you drinking? Add another $10 USD for the servo. Then we need a case, a push button, wire etc.

 

[alec_t]

If you're sure the micro servo has enough torque and is the standard analogue RC type here is a circuit which should do what you want.
With ignition on, but before the button is pressed, U1c generates servo-control pulses with a width of 1.5ms (corresponding to centre position). When the button is pressed a 10s timer, formed by U1a and U1b configured as a monostable, is started and U1b output, via R5, changes the pulse width to >2ms (corresponding to an extreme servo position). When the 10s expires the pulse width reverts to 1.5ms to re-centre the servo.

 

[4pyros]

$20 USD is overrkill? What are you drinking? Add another $10 USD for the servo. Then we need a case, a push button, wire etc.

Yes overkill even with my happy pills. It has 6 outputs and needs to be programed with a computer.
When really all he needs is a solenoid and a toggle switch.
Wish they had an even smaller three channel board.
How do you think you trigger it to run the stored script, the reset pin?

 

[KeepItSimpleStupid]

What he said he needed is something to rotate 90 degrees for x seconds when a button is pressed and operate in a motorcycle environment.

How do you think you trigger it to run the stored script, the reset pin?

There are inputs on the board and a power on place to go too.

Nope.

And 0.85 x 1.2" isn't small enough for you?

Using multiple buttons or switches to control servos
This script demonstrates how to connect your Maestro to multiple buttons. When a button is pressed, it runs the corresponding sequence.


# When the script is not doing anything else,
# this loop will listen for button presses.  When a button
# is pressed it runs the corresponding sequence.
begin
button_a if sequence_a endif
button_b if sequence_b endif
button_c if sequence_c endif
repeat

# These subroutines each return 1 if the corresponding
# button is pressed, and return 0 otherwise.
# Currently button_a is assigned to channel 0,
# button_b is assigned to channel 1, and
# button_c is assigned to channel 2.
# These channels must be configured as Inputs in the
# Channel Settings tab.
sub button_a
0 get_position 500 less_than
return

sub button_b
1 get_position 500 less_than
return

sub button_c
2 get_position 500 less_than
return

# These subroutines each perform an arbitrary sequence
# of servo movements.  You should change these to fit
# your application.
sub sequence_a
4000 3 servo 1000 delay
6000 3 servo 500 delay
return

sub sequence_b
8000 4 servo 900 delay
7000 4 servo 900 delay
6000 4 servo 900 delay
return

sub sequence_c
10 4 speed
7000 4 servo 3000 delay
6000 4 servo 3000 delay
return
Please note that this script does not do multi-tasking.
If a sequence is running, the script will not detect
other button presses until the sequence is done.
It is possible to make the buttons operate
independently, but the script would need
to be much more complicated.
Depending on how skilled you are at
writing scripts, you might prefer to use
multiple Maestros instead.

 

[4pyros]

Yes it is small.

There are inputs on the board and a power on place to go too.

Sorry I do not see any inputs on the small one, maybe the servo outputs can be bottin inputs too?