Electronics > Beginners

How to improve Solenoids open/close response time ?

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soldar:
It doesn't look right to me. I was thinking of the one posted in #6 which looks good mutatis mutandis.

SilverSolder:
Loved the aqua display in the video - look forward to seeing the new one!   :D

You know, the biggest factor in getting the water "up to speed" may be the water itself!   Maybe the response speed could improve if you had some springy tubes close to the valves that would act as a bypass capacitor for the water, to help it respond quickly!  - also avoid long thin tubes that increase the water's "inductance"...

Maybe do like a car fuel injection system, where a relatively large tube (the fuel rail) feeds the injectors as close as possible,  with a pressure regulator close to the valves.  This is all done to improve the transient response of the injection cycles, sounds like you have the same challenges!

Albatroon:

--- Quote from: soldar on March 16, 2019, 06:27:54 pm ---It doesn't look right to me. I was thinking of the one posted in #6 which looks good mutatis mutandis.

--- End quote ---
I think this circuit have an issue with my application.
I open/close the valves rapidity, on the first time It will work great, But If I opened again after a small time the capacitor will not have charged yet, And the open pulse will not be the same, (I THINK SO) !
That's why I am interested in the mentioned on replay #8, On Fig 3, It all about rapid speed operation, And looks very promising on Scope too.

Accurate open/close voltage every time at high speed.


--- Quote from: SilverSolder on March 16, 2019, 06:41:00 pm ---sounds like you have the same challenges!

--- End quote ---
Yes I do :D
I am trying to fine tune every piece step by step, After making the control PCBs working as best as I can, I'll play with water flow,pressure And lights to make it better ! Thank u
 

soldar:

--- Quote from: Albatroon on March 16, 2019, 06:55:24 pm --- I open/close the valves rapidity, on the first time It will work great, But If I opened again after a small time the capacitor will not have charged yet,
--- End quote ---
Oh, OK, I understand now.

One way to deal with that would be to replace the charging resistor with a transistor so the capacitor would charge faster.

If you have many valves in a complex system you wight want to consider having two rails (+V, 0, -V) so you can first connect between +V and -V and then switch to half voltage.

Zero999:
The bootstrapping idea is a good one. Note that each transistor should have its own base resistor, which has been omitted from the schematic.

To improve the turn off speed, a zener diode can be added in reverse parallel with Q2.

Yes, the main drawback with that circuit is it takes awhile for C1 to charge, via R1which will limit the repetition rate. R1 can be replaced with a current source or better still, another transistor. THe Hfe of Q3 will determine the charging current, so there's a bit of "Hfe suicide" here, but it should be fine.

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