Anotherpower.com Forum

Product Information => Product Support => Ghurd's product support => Topic started by: MadScientist267 on April 18, 2012, 08:11:18 pm

Title: High side LVD mod?
Post by: MadScientist267 on April 18, 2012, 08:11:18 pm

Ghurd... Buddy, pal... LOL Ok enough with the formalities...

What I need is something that works as well as the original controller, but switches the high side instead of ground.

I've had a few ideas as to how to go about this, but wanted to run it past you since you have these things dialed in to a science.

What comes to brain about this concept? :)

Steve

Title: Re: High side LVD mod?
Post by: Janne on April 19, 2012, 06:06:38 am

A relay? P-channel FET? SSR?
Just throwing some ideas to the mix... I think it largely depends of the load you want to disconnect.

Title: Re: High side LVD mod?
Post by: ghurd on April 19, 2012, 06:47:43 am

Janne is correct.

There are a couple things out there with high side switching.

Standard controller, except a few tweaks so the power fets are P channel.
If it would help, I can make up a sketch in the next few days.

Good power P-fets are hard to find, and expensive.
G-

Title: Re: High side LVD mod?
Post by: MadScientist267 on April 19, 2012, 10:25:56 am

Agreed, but luckily for me, they don't need to carry a whole lot of current. Any tranny that can handle 5A (to be safe) will work just fine.

I'm looking at a few possibilities, and yours is definitely one of them. Another is a LM339 based design, since I actually have 4 separate points that need to be monitored. Easy to set up the brain on a relatively small perf board with the threshold/hysteresis pots, and farm out the trannies to another board or boards.

The big thing is that they have almost no "operating" current. Efficient as possible is the primary concern. So that rules out things like standard relays. SSR maybe, but voltage drop is a concern on a couple of these. The P channel MOSFET is also the best method I've come up with so far as well, since I can also easily "slave" them to control more than one point in the system from a single LVD controller.

Any ideas/thoughts/caveats that anybody has are of course greatly appreciated.

Steve

Title: Re: High side LVD mod?
Post by: ghurd on April 22, 2012, 09:28:07 am

Quote from: MadScientist267 on April 19, 2012, 10:25:56 am

and farm out the trannies to another board or boards.

Any ideas/thoughts/caveats that anybody has are of course greatly appreciated.

Gate balast resistors.
If you get anything funky going on somehow, they can help save the fets... I think.
G-