This question is in continuation of my earlier question.

I have four motors with individual controllers connected as shown in the diagram below. I would like to create a controller that can control multiple or select motors as needed.

original controller wiring

Here is a small circuit that I came up with to accomplish this but my electrical engineering isn't great so I don't know whether this would actually work. I have a 12-way 5 V DC relay board lying around which I figured I could use for this. It takes a 5 V supply and then just low / high feeds to toggle each relay on or off. This is why I only show the positive in the low voltage part of the circuit.

Multi-way motor controller circuit

I don't really know how capacitors react to different situations but its pretty obvious to me that they'd be overloaded if I just tried to chain every motor off of one set, hence why I'm splitting it and using the relays basically to replace the switch on the controllers for each motor.

In theory, I think this would work, but I don't know whether the capacitors will be alright when the circuit is in the off position and both are looped together with the two neutral feeds from the two different motor windings.

If not, is there an easy way to fix it or a better, simpler solution?

Bearing in mind, I currently have four motors and 12 relays and I'd rather limit spending as much as possible.

Obviously I'm currently missing the E-stop, that was just for simplicity of the schematic. Annoyingly I imagine I'd probably just have to include a 2-pole E-stop for each motor on the neutral lines as is done in the original controllers. I'd love if I could just have one before the controller which would kill the 5 V feed making all relays return to normally open but I figure there's some regulation against not having a hard or mechanical cut off for each motor? I guess in theory the relays could stick closed then the motors aren't going to stop. As having four E-stops is very annoying and would look stupid, I'm open to any ways to make this simpler.


1 Answer 1


Here's the correct schematic for a relay-controlled hoist that requires an enable / disable SPST switch, a 'centre-off' SPDT switch and two relays for 'up' and 'down' control.

enter image description here

In the case of multiple hoists, the 'centre-off' SPDT switch would be common to all of them.

Regulations permitting, a single E-Stop switch and a relay / contactor of appropriate rating may be used to cut the 'line' & 'neutral' feed to multiple hoists.

  • \$\begingroup\$ Thanks for the suggestion. I can see how that would work well but unfortunately it wont work. I don't have any double pole relays, only singles. \$\endgroup\$
    – Tomalele
    Jun 25, 2023 at 17:41
  • \$\begingroup\$ Secondly, the power supply is at each motor point, it doesn't come from the controller so I can't toggle them in that manor. Each motor has a 4core control cable which will run to the controller I want to make. So, is there a working way to redo that for my situation? The first Schematic in my original post is the manufacturers original wiring which shows that the source is a the motor and there is a 4 core control cable before the controller. Also, just to learn more, what are the two triangles in your relay circuit? Are they like pull up resistors or something? \$\endgroup\$
    – Tomalele
    Jun 25, 2023 at 17:47
  • \$\begingroup\$ I know the schematic isn't great, but I think it illustrates what I was thinking. Please can you explain why this wouldn't work? What will happen when its in the off state and the two motor winding neutrals are connected through the capacitors? Will this cause some kind of an issue or will nothing happen without the live? \$\endgroup\$
    – Tomalele
    Jun 25, 2023 at 17:54
  • \$\begingroup\$ Also, in my schematic, when one relay is active and the circuit is complete (correct me if im wrong but im pretty sure this is exactly the same as the original wiring) besides the one capacitor that would be connected in reverse to the live. Since that capacitor is only connected to live (all be it, in reverse) would any thing happen to it or would it be fine since there is no neutral? As well as trying to get a working system, I'm also trying to improve my understanding of electrical components such as capacitors. Hence my extra questions. I hope you don't mind. \$\endgroup\$
    – Tomalele
    Jun 25, 2023 at 18:00
  • \$\begingroup\$ Your concept is okay but not workable using SPDT relays. DPDT relays are a must for motor 'forward', 'reverse' and 'stop' functions. The 'triangles' represent freewheeling diodes used to prevent arcing at the contacts of the momentary SPDT switch with centre off. \$\endgroup\$
    – vu2nan
    Jun 26, 2023 at 4:59

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