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Topic: 3 wire solenoid (Read 7 times) previous topic - next topic

majenko


you used an N channel mosfet as Q2?


No, P channel - that's why you have Q1 there to invert the signal so it drives it right.
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srusha

Quote
About midway through that design cycle I changed to a P222 N Ch Mosfet


thats what he said...

majenko


Quote
About midway through that design cycle I changed to a P222 N Ch Mosfet


thats what he said...


He was doing low-side switching - we are doing high side.

Low-side = connected to ground = N channel / NPN.  High-side = connected to positive = P channel / PNP
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srusha

Ok, got it, thanks.

I will let you know when I get the transistors how things are getting...


Docedison

Yes one and the same. The device in the picture drives a proprietary solenoid that is I believe integral to the design. the devices I designed were for bigger valves (3 to 6 inch valves) and my device in those cases was a pilot valve controller rather than the simpler solenoids for smaller valves. About the time that GAL made a serious entry into "Clocks" or irrigation controllers. they changed their name or formed a new division called GALCON. Their original controller was interesting... for the time (Circa 2001 or 2) as it used a 32 Bit Motorola processor... If I remember right. I chose to use a PC for my master controller rather than build all that capacity into my controller. I made my device a dumb controller and had "Scheduling" software designed for the PC. I wrote the prototype software in Microsoft PDS 7.1 Basic and I used the parallel port for my control link. For its time and place I thought the job worked rather well. At that time I did very little programming beyond a simple 8 valve controller (With A PIC16C57, Gawd what a Nasty little Chip, it had "Paged" ram". I might point out that this work started in 1991 and essentially ended in 2005. At that time I changed my work to soil measurement tool design work. EC, Moisture, most of which is still covered by a non disclosure agreement... although the company is dead now for all practical purposes I was never released form the agreement.

Doc
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