[Khalid]

Markwind, nice idea and can be implementable with some limitations..
1- Timing issues, Here we are dealing with Water and gravity and the timing between each row of water drops is very critical.
2- We will be limited to scrolling of programmable words only.
3- We will be limited to very few solenoid valves (10 or 15) considering the no. of rows of the sign. (No. of Rows of sign= Solenoid Valves). So very less resolution.


yesterday i purchased a lot of 24VDC solenoid valves from scrap shop. I got 0.8 US Dollar each. Their were only 15 available with the shop so i purchased all of them. They told me that on monday they can supply more of them. So with less than 10 US Dollar i got 15 Solenoid Valves.

They also available only solenoid with Stem plugs, 12VDC and i purchased one brand new for the same price.

Now i am thinking two things:

1- Controlling of those solenoid valves with AVR microcontroller i.e. Arduino
2- Controlling the Solenoid with PIC Microcontroller i.e. 18F4500 that can handle USB interface easily.

Using Arduino is simple as it contains USB interface and can take serial data from/to computer, but salvaging the complete Arduino for this project is not cheap. The PIC interface will be quite simple and cheap only if i know how to interface the computer with PIC thru USB.The only problem is interfacing USB with PIC that i do not know how to do it.

[Geof]

Get a big dot matrix printer. The printer head has numerous tiny solenoids that drive the individual printing wires and each solenoid is powered by a conductor in the ribbon cable running to the print head. Wire these individual conductors to your little solenoid valves and the printer would print in drops not dots.

You might need to connect the solenoid valves through little power transsitors with the printer signal triggering the transistor so you have enough current available to drive the solenoid valve.

Probably regular solenoid valves will not respond fast enough to give nice drops without any dribbles. What would be needed are valves like those used for fuel injection where there is a little needle that opens and closes right at the orifice. This starts and stops the flow very quickly and precisely.

[Khalid]

Geof, that is another good idea I often amazed how peoples brings different solutions for one problem ..Getting the Dot Matrix printer and hacking it for this purpose will require some skills that a person talented like you have or RomanLini or Russell AKA epineh...but again your idea is Out-of-the-Box and workable...We will definetly think on that...

In the above post, i have attached the pictures of the solenoid valves, the solenoid ON/OFF by applying 24VDC but still to be tested with water.

[Khalid]

Here the pictures of solenoids