12VDC to 12VAC

[Ricardo]

Hi there,

I'm looking for a circuit design to convert 12V DC into 12V AC, at 50Hz or 60Hz. This is to control a solenoid rated at 12V 50Hz AC, and 8W. As it turns out, the solenoids I plan to use are rated for a higher pressure under 12 AC control than 12 DC, so that's the reason for going this way. I'm not sure I really understand why that's so, but it's what the specs say... A step-down transformer isn't an option, as it will be running in a car. :wink:

Anyways, I've spied a few 12V DC to 110/240 AC circuits, and was wondering if these are usable in modified form? Is it just a matter of dumping the transformer, tweaking the values, and going for it? Eg, **broken link removed**

Also, can anyone think of a sensible way to implement PWM control for this thing? I understand how that works with DC, but in this context AC PWM confuses me.

Thanks,
Ric.

 

[Sebi]

For me the AC relays and solenoids always work fine with half DC voltage.If Your 12V AC solenoid give not enough pressure with 12V DC, change it.

 

[Ricardo]

That's odd, because here's what's on the spec sheet:
Pressure range 50 Hz from 0 bar (0 PSI) to 70 bar (1015 PSI)
Pressure range 60 Hz from 0 bar (0 PSI) to 70 bar (1015 PSI)
Pressure range DC from 0 bar (0 PSI) to 50 bar (725 PSI)

It'll be on a nitrous oxide line with a bottle pressure up around 900 psi, so I'd prefer to run it at the higher rating if I can.

 

[Ricardo]

Nobody's got links to suitable info / tutorials / designs? I'm sure it must be out there, but my Google skills seem to be lacking... FWIW, it's going to be part of an nitrous oxide system, so any help with it is appreciated. The design will be posted online as a controller complement to the info at www.nitrous.info

 

[Ricardo]

OK, so I've figured out basic sine-wave inversion of 12V DC to 12V AC. Now I need to know the best way to pulse control an AC driven solenoid. Does PWM from on the DC side of the inverter work OK, or is there a better way of doing this?