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roopakjada
01-27-2013, 12:12 PM
Hello All
I need to design a system wherein i need to control 1000 electromagnetic valves. The control will be bidirectional i.e. reversal of direction on change of polarity, all the valves will need to be switched at once without any time delay. What would be the best way to achieve this? also the valve will need to be in any one of the position so we can have a circuit wherein in the absence of the signal the polarity will be reversed

Specifications of Valve
12V @ 30 mA

vikas
01-27-2013, 02:56 PM
What is the distance between devices ? what input does the vale take ?

roopakjada
01-27-2013, 03:47 PM
All the devices are pretty close, distance wont be an issue, we need to apply a voltage across the terminals to drive them, opposite polarity will reverse the direction

MohitM
01-27-2013, 10:34 PM
1. Need to see the datasheet of the valve;
2. This is real-world engineering, so "switched at once without any time delay" cannot mean 0 ms. What are the upper limits? Be reasonable, please;
3. Not all valves are built alike, so even if you can design a valve-driving setup with instantaneous action, the valves themselves might not switch together.

roopakjada
01-27-2013, 10:43 PM
well the upper limit can be 200ms on the electronic side.

vikas
01-27-2013, 10:58 PM
Well in that case build a mosfet hbridge , It should be able to handle the current ( 30 A ) and reverse polarity as you wish.

You should be build one for real cheap and with locally available mosfets , choose logic level mosfets if driving from < 5V . Rds be low at < 5 Vgs.

roopakjada
01-27-2013, 11:07 PM
oops I'm sorry i forgot to mention that each valve needs to be individually controlled that was the whole point of this post controlling them individually

vikas
01-27-2013, 11:57 PM
In that case use a cheap pic12f with 10 bit addressing in i2c with atleast 4 gpio free and some eeprom , then source it to a microchip / any other cheap hbrdige ic which can do 12v with 30ma.

For starter -

PIC12F629 + L293d ( locally sourceable and cheap ) , you can also make a small transistor hbridge as the current is very low which will be even cheaper.

MohitM
01-28-2013, 10:46 AM
And how are you going to control these 1000 valves individually?
Do you have some kind of protocol ready to individually address these valves from a main controller?
What's your budget for the valve driver circuit?

roopakjada
01-28-2013, 01:25 PM
I'm still working out the protocol, I'm thinking 1 master controller n slaves over I2C and then multiplexing on the slave side(a rough sketch still need to work out the addressing, data etc) I'm thinking of some circuit wherein the polarity is automatically reversed when there is no signal (a voltage) so that will work with multiplexing when a input is present the valve will be driven forward and in absence the valve will be automatically reversed.