richacm

Hi,

I have ripped apart a solenoid I found which controls water flow. I can't find out anything about it on the internet and there is no part number on it. However its part of a Gardena T14e water timer which switches on and off the water at pre-set times.

I tried to get readings from the unit when it sent messages to the solenoid...however my multi meter just picked up a very low V spike - I'm guessing that the signal may have been digital????

Anyway I blew up the unit during my testing so now I'm really in the cart. The unit has a microcontroller in it that runs at 5V and I'm guessing this drove the solenoid. Does anyone know of any data that will drive the solenoid? Really hoping someone has had experiance with these and can say what normal things are I should try.

Thanks heaps,

Craig

rjvh

what is the suply voltage of the whole unit??

can you find some regulator inside that indicate a lower voltage or not ?

can you messure the coil of the solenoid (how many hm

Robert-Jan

richacm

I'm not going to be very helpful here! The Entire unit runs off a 9V supply. The unit is totally sealed (since it was used near water) but from the specs the Microchip runs off of 5V.

The solenoid is completly sealed, I can't get in there at all....not much help I know!

Pommie

Could you use a valve of this page? The 12V one at $18 looks pretty good. Alternatively, can you find a link to the unit you have dismantled.

Mike.

rjvh

as it is already broken than why not try to open it (brutal force)

and try to get the leads of the solenoid

most likely you can retrieve the leads and operate it this way try with 5 V for activation and step it slowly up if that doesn't works

Robert-Jan

richacm

Hey I am making progress! I figured out that to open the switch I need a 0.1A surge to the sensor. So I place a 5V supply with a 100hm: resistor in its path (sensor must have 40hm and spike the line and hey presto solenoid activates....just need to figure out how to turn it off now

rjvh

if you have a 5V with a 100hm: than the max current is 0.05Amp (short circuit)

can you measure the resistance of the coil?

to operate it it's just simple let a current through or not (put a switch in series)

Robert-Jan

Pommie

It may be a latched solenoid, does reversing the battery close it?

Mike.

rjvh

good point I didn't think on that one

Robert-Jan

richacm

It is latched. I reversed it and the current went way up - short circuited 1.25A...must be a diode of sorts inside the solenoid. The solenoid didn't open though.

33.3Ohm resistance in the solenoid when I put the multimeter across it.

ericgibbs

hi rich,
Are you saying once energised the valve remains open, even when the power to the solenoid is removed.?

Is this an 'air' test or with actual water,?

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

richacm

Yes Eric, that's what happens.

There is a little washer sitting on a spring on top of the solenoid. When 0.1A goings in to the solenoid it magnetises it and sucks the washer on to the solenoid thus opening up the valve. You can then release the 0.1A and it remains magnetised to the solenoid - i.e. stays open without any power.

You then need to pass X to the solenoid and it releases the magnet. I have tried from 1A down to 0A to no avail at this point.

Craig

ericgibbs

hi,
I have looked at the spec for the Gardenia water drip feed system, I suspect the valve requires water pressure to reclose the valve correctly.
The pulses just pop the valve open for an instant, then it recloses.

The overall system is fitted with a water pressure regulator to ensure correct operation.

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

richacm

I tried it (when the control unit worked) and when I clicked on it sucked the magnetic on to the solenoid and when I clicked off it released the washer. I.e. it popped up and down on the solenoid. So I'm pretty sure I should be able to do the same thing without the need for water.

I'll try a few more things today with it and see how I go. I really like this one though cause it doesn't need a constant holding amp. Most solenoid values I see have an inrush amp of 0.4 and then they need a holding amp of 0.2 to keep it open. This one doesn't which is really cool. It also works off of 5V as well.

Cheers,

Craig

richacm

I got it....sorry I stuff up the reversed setting. It's 0.1A current surge to open and -0.1A current surge to close

Cheers everyone