Solenoid Valves

[3lectrokid]

Hello,

My washing machine recently broke so we brought a new one. Before they took my old one away I salvaged the motor, main board, water pump, speed controller and the solenoid valves that allow water to pass into the machine.

I would like to get the solenoids working but they are rated at 220-240VAC 50hz 0.22A. Is it possible to get them working directly off a 30VDC supply. If not I was thinking of using an astable transistor multivibrator circuit (or a 555 timer) to create a 50hz logic signal going intio a mosfet to control the solenoid. would this work or does it need to be true AC. I don't think it will work with DC because the current would burn out the coils pretty quickly.

I was also hoping to get the pump working aswell in the same manner. however this isnt my main thing im trying to do but information would be helpful. I will of course create a diagram of the motor if you wish

Thanks for reading and all help is welcomed,

Dave

 

[MikeMl]

Solenoids designed for AC will pull-in on DC, but may over heat. You will have to determine the DC voltage that reliably pulls-in the solenoid, but then measure the temperature rise over a min or so. For a 220V solenoid, I would expect the DC pull-in voltage to be ~50V. If the solenoid gets really hot, you may have to implement a two-step DC drive circuit, where you use say a 30V pulse to initially pull-in, and then drop the voltage to say 20V to keep it on.

 

[3lectrokid]

by pull in voltage do you mean the voltage that is required to initially open the solenoid to allow water in. if so I would have to build a circuit to increase the voltage. As it is only needed for a brief period do you think I could use a buck boost converter store store say a 50v charge and let it out quickly. I would then have to switch over to a smaller voltage with doesnt need to be increased. would this idea work or would i need to do somthing else. I can only supply max 30VDC

 

[MikeMl]

You can pre-charge a large capacitor to say 100V, and then connect it to the solenoid. As the capacitor discharges into the solenoid, that will initially pull it in. To hold it in, connect a lower DC voltage through a series diode, which prevents the 100V pulse from backfeeding into the 30V supply.

 

[3lectrokid]

I realise its simple electronics but will a capacitor slowly charge and increase in voltage higher than the input voltage or will a voltage increaser be needed. And Happy New Year!

 

[SABorn]

Have you considered just buying a cheap solenoid that has a coil rated for lower voltage like one that is used in garden watering systems.

Depending on the style of solenoid, i have also replaced the 220v coils with a coil off a lower voltage solenoid.

Most of the mains solenoids will burn out is they dont have water flowing through them as the water is used to transfer the heat away in long operations.

Pete.