most starter solenoids with two terminals have one for pulling in the solenoid and the other for shorting the ballast resistor in the ignition.

I'm not talking about starter solenoids, which are not rated for continuous duty. And even then starter solenoids with two terminals (which are NOT the ones I was talking about) predate electronic ignition systems by a few decades.

 

I'm not talking about starter solenoids, which are not rated for continuous duty. And even then starter solenoids with two terminals (which are NOT the ones I was talking about) predate electronic ignition systems by a few decades.

Follow-up: Older starter solenoids, at least some models, that had two terminals were so that they could be compatible with both 6V and 12V systems.

 

I will do some experiments tomorrow, as it still keeps making me go cross-eyed knowing that the power supply has all of the wires independently routed. I will pull the leads from one side and see if the remaining side shows signs of the ghost voltage. It's odd that the 5v, led thermostat shuts down no problem but the high power Corsair fans manage to keep pulling even with the inline rheostat turned all the way down. If need be I can just install 2 switches, but I want to look into the specs of all the electronics if they can all run on 12v then I would prefer to just remove the 5v altogether. Many thanks, it has been a long time since I fiddled with DC projects, that are not in an automobile.

How the circuits interact is highly dependent on the circuits themselves, not just how the power is routed to them.

By running a complete set of wires (i.e., two wires per supply voltage) even though they share a common connect allows for better management of ground currents on the connected boards. Sometimes you want to keep them separate on the board and return them separately to the supply and other times you want them to be shared on the connected board. Factors such as current densities, noise susceptibility, ground loops, shielding, etc, etc, come into play.

 

Well with both positives present there was shorting present. But if I removed one or the other positive all was normal. If I kept both positives and did away with a ground still had shorting. So I ended up running the grounds to separate switches and everything is perfect. I can only assume that the internal routing of the power supply/adapter brick allowed for the positives to leech off on another. Thank you all for you asistance!

 

All this babble about "ground" is a dead giveaway that very little knowledge and competence is present here, except probably "the F-15 guy". Clear your head of preconceived notions, assumptions, and ideas of how you think "it should be" because obviously the system is not going to work that way.

Those 2 individual, separate, insulated, isolated conductors are not the same, electrically common thing as each other. Interrupting a circuit will act as an interruption at any point. Since you are NOT dealing with any grounded conductors (or systems even), there are no reasons for placing your switch(es) on one "side of" the circuit, as opposed to another. Since "ground", " negative" and certainly other terms are not clearly understood by you, and the ACTUAL functions of the individual conductors ("wires") are also not entirely known, you should switch ("disconnect" or "interrupt") one or both accessible points of each circuit, and certainly not be connecting other things together. Incidentally, to repeat, your circuits shown, and devices described, have no points that are grounded, or that would be correctly called " grounds".

 

Switching grounds is easier and dumb u know.
You should always switch positive., not the ground

Look at any car/auto computer control schems. Fuel injectors and almost all othe system controlled by the computer(s) are grounded at the computer and system positive at the device.

 

Ya.. I have seen that.
I do work on those u know.
I said easier and to me it is dumb. But hey if the designers see that way, who am I to argue.

 

Ya.. I have seen that.
I do work on those u know.
I said easier and to me it is dumb. But hey if the designers see that way, who am I to argue.

What the engineers at work (Delphi Packard Electric) that did a lot of GM design work said it was two main reasons. Weight savings, one large gauge supply wire linking to a few different devises, meant fewer supply wires. And a lowside switch is easier than a highside.

 

I didn't see it brought up yet, but I believe the computer fans are variable speed controlled by the motherboard. Could be that what you interrupted by the switch wasn't the "ground" or "negative" or "common" or whatever is the term preferred which won't bring any personal attacks against me, but instead it might be the PWM fan speed signal. Just a total "out of my butt" guess, but maybe the fans have a failsafe speed to run when they detect that their speed signal is missing.

 

Now, is this low-side switched or high side switched?

I think there are plenty of examples of switching between load and ground.

 

Yikes this is going a little sideways but hopefully somebody is going to learn something. I am pretty competent with electronics, I just was baffled by the power supply's lack of isolation. It caught me off guard. I always think of DC as the negative pulling, so without the negative the power has nowhere to go. It applies with both positive and negative, but in the case of the power adapter I couldn't use one switch for +12v and +5v, so I figure go for the grounds. I am sure looking at a schematic of the power supply would reveal what was going on. I was just distraught from being outsmarted by a "made in Chiner" power supply?!? Thanks for all the input!

P.S. automotive starters even today have secondary lead some vehicle types carry a secondary ignition relay silenoid. The standard in car relay allows the power to go and a higher rated under hood relay supplies the juice. Also no Honda ever had one of these, snicker.

 

Now, is this low-side switched or high side switched?

I think there are plenty of examples of switching between load and ground.

View attachment 85027

We normally use ground switching for safety circuits where a series of door switches or interlocks each control solenoid locks. A simple indicator lamp on the ground switched side is lit when the door is open , off when safe and each door is still locked if the door switch shorts to ground. We then daisy chain a master safe signal though each of the lock switch closed contacts to indicate that all interlocks are safe to an enable button with a positive side latch circuit to unlock all. It's a human factor that one lamp on of many is easer to see than one lamp off of many on. You could do the switching on the positive side but because most interlock failures are switch related we don't like having the full current of the control voltage sitting there waiting to short to ground, blow a fuse or burn a wire.

 

I didn't see it brought up yet, but I believe the computer fans are variable speed controlled by the motherboard. Could be that what you interrupted by the switch wasn't the "ground" or "negative" or "common" or whatever is the term preferred which won't bring any personal attacks against me, but instead it might be the PWM fan speed signal. Just a total "out of my butt" guess, but maybe the fans have a failsafe speed to run when they detect that their speed signal is missing.

Hi, I wish it would have been that easy, but no the harnesses are only two wire pre set to +/-, no signal wire. It was due to the internal mapping of the power supply/ brick/ laptop style supply/ what the hell are these things called? The shorting power was miniscule at best. I appreciate the straight forward thought though.

P.S. even if you had nailed I don't think I would have owned up to that one. j/k