Which switches? The mains switch? That would stay, at least one of them has to stay.OK, now I see I went back and looked at that picture more closely. So is another one of the buttons available? If not, the control can be achieved rather easily using a minor variation on the original scheme, EXCEPT that the switches will be switching DC. AND adding any diodes will prevent operation.

That scheme works like this: Both supplies are powered, and the positive of one is tied to the negative of the other, and that junction also ties to one wire from the actuator The other wire from the actuator connects to one side of both switches. The second side of one power supply goes to the open switch second terminal, the second side of the other power supply goes to the second terminal of the other switch. Thus one switch will supply a positive voltage and the other switch will supply a negative voltage. And if one of the other buttons is available that can be used to energize the two power modules.
As for a seperate means to remove that gap filler, that could be made to be part of the mechanical linkage.

No, he has a switch panel with up and down switches on it he wants to use.

 

No, he has a switch panel with up and down switches on it he wants to use.

I understand the up and down switches and in my description they would be used. But ALSO, there would be another switch to provide mains power the two 12 volt supplies. That is in addition to the up and down switches. To raise the lid, press and hold the UP button and then pres the enable button, and up comes the lid. To lower the lid, press and hold the down button and then the pres the enable button. Les likely to be accidentally operated. Plus, when operated as I decribed, NO SPIKES because the circuit is not closed or opened while current isflowing. And the power supply rise and fall times are much slower than a switch opening.

I do wonder what is down below, that it needs such a slick system to open the lid. What could it be.

 

Using the up and down switches as the TS shows in post #1 together with the schematic in post #4 would avoid the need for a third switch to remove power from each power adapter. It would still require adding limit switches and an interlock with the latch.

Les.

 

OK, one more possible arrangement very much like the original that did not work, except that each supply will also have a DC relay, single pole, normally open, so that when the supply is off, the relay is released and the contact open and so it is disconnected from the motor. That will remove the problem stated in post #1. The relays can be those cube type ones such as used for automotive horn relays. No diode because they are directly across the supply, no instant circuit opening. This will alow using the up and down buttons exactly like posty #1, and add the very least amount of additional hardware.

 

MisterBill2, I think your suggestion in post #24 will work BUT would have a problem if both up and down switches were on at the same time.
Using SPDT relays would solve this problem.
Les.

 

I think that there was a comment that they were mechanically interlocked, so that would not happen.
In addition, why accommodate those who chose to do the wrong thing.
Look at the photo, the buttons are well marked and no reason to press both at once. And to keep that from happening, just install fuses that are a lot of work to replace.

 

Hi Everyone, thanks for all the patience and the additional help. I've (finally) received some of the stuff I need to build the circuits (lockdowns and all). I will try and have a go at it this week and will come back with progress updates (and of course a lot of questions).

@MisterBill2: Down the rabbit hole you are most likely to find the access to Wonderland or a washing machine...

 

@MisterBill2, @LesJones: It is mechanically impossible to press both up and down switches simultaneously. I will have a go at it this week as well