Remote Timer Reset Black Box

[kadini]

I am sorry I didn't make this clear.

After my initial test circuit trial failed after checking connections and various other things I finally just hooked the solenoid directly to the power supply.

Doing that I am getting very sporadic firing of the solenoid.

The solenoid checks out always at 56.4 ohms.

The power supply by itself always gives 12v to my volt ohm meter.

But when I hook the power supply up to the solenoid it mostly doesn't work. At the connections when the solenoid isn't working there's nothing. But when the solenoid does trigger I get 12v from my meter.

I can't swear those 2 sets of wires twisted together give a good connection but my intuition is it should be adequate.

Today I am buying some terminal end fittings for the wires and a new power supply because it's not that expensive.

 

[kadini]

Oh, with the power supply connected to solenoid I am also omitting the diode.

And, apparently the polarity of the wires into the solenoid (both black) doesn't matter. Although I understand I need to carefully observe polarity for the circuit including the diode. If I can ever get the solenoid/power supply to work reliably.

 

[AnalogKid]

apparently the polarity of the wires into the solenoid (both black) doesn't matter.

Correct. As long as the solenoid does not have a suppression diode built-in, the direction of the current through the coil does not matter. Almost no solenoids have a built-in diode, but some DC relays do.

ak

 

[kadini]

OK, got it working! The problem was the power supply. Not sure if it was defective or just under powered for the task. The old one was rated at 0.7 amps and the new one at 1.5 amps, which was the only one they had.

But, the solenoid doesn't have enough force to depress the reset button.

So, guess I'll got look for some type of a force meter so I don't have to guess (again) what the needed solenoid force is.

Also, the 555 module works perfectly. Only issue is how to adjust the time interval the solenoid is energized remains a mystery. I tried turning the adjusting screw both directions up to 2 full turns with no apparent effect. The current interval, about 3-4 seconds, is probably OK.

I will win this battle!

Thanks for all your help.

 

[rjenkinsgb]

But, the solenoid doesn't have enough force to depress the reset button.

Make sure the solenoid is within a fraction of a millimetre of fully home when the button works, then add a stop behind the solenoid so it only just releases the button.

Magnetic field strength is related to armature gap (air gap) by "square law"; half the gap you get 4x force, a 10th the gap and you get 100x the force!

 

[AnalogKid]

how to adjust the time interval the solenoid is energized remains a mystery. I tried turning the adjusting screw both directions up to 2 full turns with no apparent effect.

That is a 10-turn pot. Keep going. The adjustment probably is very non-linear, with something like 80% of the pot's range covering 5 to 10 sec, and 20% covering 1 to 5 sec (assuming a 10 second max period). That type of pot usually has a friction clutch at each end of the travel, so keep turning until it suddenly needs more force; that is the end.

ak

 

[danadak]

One comment, in application I posted earlier in thread a PWM driven servo
was used. That allowed me to tailor the pressure exerted on switch so that
I could insure button was not brute forced into failure over time, eg. too much
applied actuation force.

Just a thought.

Regards, Dana.

 

[kadini]

Yes, I read you previous post and candidly did not fully understand it.

I reread it and still have questions.

For one I have no way of monitoring if my device is online or not except to go open the Tablo app (on Firestick) and see if it's there.

I am very wary of pushing too hard on the reset button. This morning I figured out I need 9 ounces force to reliably trip it. Now I am looking for a compact 12v DC push solenoid that can do the trick.

Any help in that department is most welcome.

If I end up having to get a solenoid with more force than needed I think it can be mitigated with stop limits or some sort of elastic mount.

But I think I'm going to need an even bigger power supply to make whatever it is work.

I am open to using a servo if that is a more expedient choice, but I don't know anything about them and you didn't show which one you were using. At least I have a general idea what solenoid I need.

As always, thanks for all the help.

 

[kadini]

Make sure the solenoid is within a fraction of a millimetre of fully home when the button works, then add a stop behind the solenoid so it only just releases the button.

Magnetic field strength is related to armature gap (air gap) by "square law"; half the gap you get 4x force, a 10th the gap and you get 100x the force!

 

[kadini]

There is no gap between the end of the solenoid and the block it pushes on to activate the reset button. I push it up until everything is touching and then lock it down. I was afraid I was going to have to come up with a way to relieve excess force but not a problem with this solenoid. It can't even trip the button period.

 

[rjenkinsgb]

In the photo it looks like the solenoid is all the way back, with a long spring visible.

It should still be pushed nearly all the way in when it is not powered, so you are only using the final part of the overall stroke; that will be vastly stronger than the start of the movement.

This shows the relative strength of some type of solenoid, vs how close to being fully in it is; the proportions are similar with any solenoid, though the stroke and force scaling will vary:

Think of it like picking up a piece of metal with a magnet - too far away, nothing happens; as you get closer, it will get to the point the pull is just enough to lift it - but once it touches or if very close to the magnet, it takes a lot more force to pull it away.

No different with the solenoid, it needs to be pushed in as far as you can when it is idle, as long as it still has enough movement to press the button.

 

[kadini]

You are correct. I got that absolutely, totally backwards. I thought highest force was with the shaft retracted into the housing.

Took a screen shot of my solenoid specs. and I still don't get to 9 ounces.

I actually tried just to be sure and, of course, I was right about that.

Maybe I can rig up a pivot with a 2:1 mechanical advantage but not sure I have enough stroke to make that work. Reset button depression seems to be on the order of 0.05".

May still have to buy another solenoid, one that has some excess capability. But it won't be the monster I was envisioning before you set me straight.

I was expecting a learning experience but not this steep of a curve. And not falling off the curve so many times...

 

[kadini]

Small Push-Pull Solenoid - 12VDC

Solenoids are basically electromagnets: they are made of a big coil of copper wire with an armature (a slug of metal) in the middle. When the coil is energized, the slug is pulled into the ...

www.adafruit.com

This solenoid should do the trick. I can just replace my wimpy one with this 5 newton (18 ounces) one?

I am pretty sure it will work only reason i ask is they mention the diode in the wiring diagram, but they also mention a micro chip. I think that's just to hook it up to one of their controllers?

This one is actually better than the one I have and paid much more for in just about every way.

 

[dougy83]

Small Push-Pull Solenoid - 12VDC

Solenoids are basically electromagnets: they are made of a big coil of copper wire with an armature (a slug of metal) in the middle. When the coil is energized, the slug is pulled into the ...

www.adafruit.com

This solenoid should do the trick. I can just replace my wimpy one with this 5 newton (18 ounces) one?

I am pretty sure it will work only reason i ask is they mention the diode in the wiring diagram, but they also mention a micro chip. I think that's just to hook it up to one of their controllers?

Yes, you can just drop it in place of the other solenoid with your current circuit.
Re the time adjustment, you may just need to turn the screw more; it'll be 10 turns between minimum and maximum. I don't know the specs of the timer, but it's possible you may already be at the minimum period it supports.

 

[Dr_Doggy]

is that your internet modem you are switching ?

if you have problems with the modem, switch it out for another one, ISP provides these for free.

if new modem does not fix issue then you have a cable issue.

if you can get in to the settings there may be a section that lists the modems TX & RX db's.
compare db's between old and new and if there is a difference you know furshure it was modem.

even coax with good signals(db's) can have faults on the wire. (gold splitters are a #1 to target), but even a proper one can blow at any time . but sometimes not enough to create an "outtage".

who is your ISP? what country?

 

[kadini]

It works!

Just need to make a couple of covers and it's done.

Thanks for all your help!

 

[kadini]

The device being reset by this apparatus is a Tablo DVR.

But the problem is with the modem. If I could upgrade the model, set a static IP address, and do port forwarding I wouldn't need this reset device.

But the people who actually live in the house, most of the time, don't want to mess with it, even though it would be better in every conceivable way.

I had a lot of fun doing this...