Wireless TX/RX hoist control

[swervyn]

Hello members and most knowledgeable ones

My project involves a 240v hoist that is being used to lift goods from one floor to the next. 2 floors only.

I purchased a control system from carymart to get rid of the pendant controller and use a wireless transmitter to control it.

The receiver unit also has connections to enable limit switches and manual switch controls to be used.

On each floor will be a "call button", so to speak which will be connected to the manual switch controls. Planning on using an illuminated momentary push button switch.

Now I pulled a 12v relay out of my car to test how to connect it with help from you tube and got it all working using a 12v battery as the supply. Circuit energises and LED light comes on when momentary button is depressed and all switched off once limit switch triggered.

Yippee I thought as the terminals on the carymart receiver show 12v dc. However when I connected my makeshift test setup to the receiver it wouldn't control the relay and you had to keep the momentary button depressed for it to work.

Reading show that the output voltage from the receiver drops to 3V once the start button is pressed (from 12V). My best guess is that this is not enough voltage to control the 12V relay, hence not working (and very dull LED).

So once more, many hours of googling looking at 3V low level signal relays and they are minuscule. Is there a simple way of getting 12V at the relay from a 3V source? For ease I would like to use a 12V relay so my fat fingers can work with it and hopefully just use a socket mount.

I can get around all this by just using a push button switch that needs to be kept depressed until the hoist platform reaches the limit switch but this just seems too easy. Why not use relays and an illuminated switch and set it up as a single push switch for each level. Except this is starting to do my head in and now is my time to ask for help!

My first post here, not sure on the rules of web links yet but can link to receiver and attach a pic of my circuit in needed.

Hopefully all this makes sense and my terminology is understandable

Thanks in advance!

 

[crutschow]

I'm a little confused about the connection of the "start" button versus the connection from the carymart receiver.
Can you post a diagram of that connection?

In general you could add a transistor to control the relay from the 3V signal.

 

[swervyn]

I'm a little confused about the connection of the "start" button versus the connection from the carymart receiver.
Can you post a diagram of that connection?

In general you could add a transistor to control the relay from the 3V signal.

Hi crutschow, thanks for your interest

In this pic the battery is essentially the carymart receiver, it shows 12v "at resting" but drops to 3v when actuated, pic taken from youtube with some of my text

the receiver is this one:

Manual: Located at bottom of this post (Mod)

https://www.carymart.com/high-power...otor-in-positive-reverse-rotation-p-1932.html

thanks for any advice you can offer

 

[crutschow]

Your connection diagram makes little sense.
It will not work with only one limit switch connection and one output connection as you show.
And you do not connect the limit switch in series with the load.

The outputs of that receiver are simply two relay contacts.
You connect the external 12V to the contacts to power the external relay/load.
For example, connecting 12V to the Output COM terminal will then cause the UP or DOWN terminals to be connected to 12V when the Up or Down buttons are pressed.
Or you can use the relay contacts to directly control a motor up to 1/2HP, 240Vac, as shown on the relay housing.

Any remote manual control buttons go the External Device inputs.

The receiver will be set to latch if there are no jumpers on the jumper terminals.

The latch will be released when the corresponding limit contact is closed, as shown in the manual.
The limit switches go only to those board terminals, nowhere else.

You should carefully read and understand everything in the manual.

 

[swervyn]

Your connection diagram makes little sense.
It will not work with only one limit switch connection and one output connection as you show.
And you do not connect the limit switch in series with the load.

The outputs of that receiver are simply two relay contacts.
You connect the external 12V to the contacts to power the external relay/load.
For example, connecting 12V to the Output COM terminal will then cause the UP or DOWN terminals to be connected to 12V when the Up or Down buttons are pressed.
Or you can use the relay contacts to directly control a motor up to 1/2HP, 240Vac, as shown on the relay housing.

Any remote manual control buttons go the External Device inputs.

The receiver will be set to latch if there are no jumpers on the jumper terminals.

The latch will be released when the corresponding limit contact is closed, as shown in the manual.
The limit switches go only to those board terminals, nowhere else.

You should carefully read and understand everything in the manual.

Apologies, the drawing was somewhat simplified to try to clearly explain my problem, I will try to whip something up more thorough

Everything works as expected, all I want to do is use an illuminated switch (with a 12V LED) for the manual control button, the output from the external device outputs is 12V "at resting", it drops to 3V when the manual switch is actuated, not supplying enough power for a 12V relay

The limit switch (from the limit switch terminal) works in conjunction with the remote transmitter (NO) but does not work with the manual switch in NO, it needs to be NC, hence I will be using a NO/NC limit switch which will indeed be connected to the manual switch

Stay tuned for a drawing of sorts

 

[swervyn]

Hopefully this is a little clearer, forgive my lack of knowledge of circuit drawings!

I have only shown 1 side of connections for clarity, the other side (S1) is duplicate. Disregard the blue arrows on the PCB, they are from the stock image.

The limit switch terminals only work with the wireless transmitter, they do not work with the manual switch, this is why I have used a NO/NC limit switch. Carymart were no help (I dont think the guy knew how to do it either) so took a bit of nutting out to get it working with my limited knowledge.

Everything works now as expected however to use the manual pushbutton momentary switch to control the hoist you have to hold the button in until it reaches the limit switch.

What I am trying to do is to use a latching relay so that the manual momentary switch is not a push to hold switch. This switch will also have an illuminated ring, 12V LED. Hoist will run until it reaches the limit switch then switch light will turn off, relay will reset. Basically the same as a "normal" elevator call button.

I have all this working as shown in my first picture, using a 12V car relay and a 3S lipo battery. The problem I have is that the wired control terminals for the manual switch are 12V at "resting" but once the manual switch is activated the voltage drops to 3V not supplying enough power for the 12V relay (plus I need 12V for the switch LED)

This is why in the manual it states you can use external devices with "low level output signal" to the manual control terminals.

I am surmising that a 3V relay would work but they are tiny and I still would not have 12V for the switch LED.

Hopefully this makes sense

 

[cowboybob]

I have all this working as shown in my first picture, using a 12V car relay and a 3S lipo battery. The problem I have is that the wired control terminals for the manual switch are 12V at "resting" but once the manual switch is activated the voltage drops to 3V not supplying enough power for the 12V relay (plus I need 12V for the switch LED)

Not really sure how your have this all wired up, but...

You ordinarily don't see that radical a shift in voltage level(s) when a load is added to a circuit. My first thought was that the battery you're using is under rated (i.e., A or mA per Hour rating) or needs charging.

 

[large_ghostman]

What did AAC and EEV blog say was best to do

 

[crutschow]

Everything works now as expected however to use the manual pushbutton momentary switch to control the hoist you have to hold the button in until it reaches the limit switch.

Did you remove the jumpers on the board to make the circuit latching, as shown in the manual and as I previously mentioned?

 

[swervyn]

Did you remove the jumpers on the board to make the circuit latching, as shown in the manual and as I previously mentioned?

Yes, tried that previously, the jumpers only take effect when using the wireless tx, they do not work with the manual switch. There are 2 jumpers, connecting jumper #1 sets control to momentary, removing all jumpers sets control to latching. No idea what jumper #2 does.

I have now just wired a momentary push switch to control terminals with nothing else connected. When "resting" the voltage across the terminals is 12V but now when I activate the switch and hold it drops to 0V?? Not sure why I was reading 3V before unless it had something to do with the relay??

It is easy to use it as is, I am just trying to make it harder for myself and to be able to use an illuminated switch that will latch when pushed

 

[crutschow]

Here's a typical latching DPDT relay circuit:
12V is an external power source.
The "Push to Break" would be the NC limit switch.
The switch light could be connected to pin A.
Pins C and D could go to the wired control terminals.

 

[swervyn]

Thanks crutschow, I can see how that would work, might take me a few days to get to try it but will keep updated

Would a 12V wall wart be ok as the external power source?

 

[crutschow]

Would a 12V wall wart be ok as the external power source?

That would be fine as long as it has sufficient current capacity to operate the relays and LEDs.

One thing not shown is a diode to suppress the inductive transient of the relay coil, which can erode the switch contacts.
For that, connect a diode (any general purpose diode such as a 1N4148) across the relay coil (cathode to plus).

 

[large_ghostman]

That would be fine as long as it has sufficient current capacity to operate the relays and LEDs.

One thing not shown is a diode to suppress the inductive transient of the relay coil, which can erode the switch contacts.
For that, connect a diode (any general purpose diode such as a 1N4148) across the relay coil (cathode to plus).

One word of warning, get your diodes from somewhere decent, recently i ordered 50 from ebay, they are complete garbage, a low current 5V relay destroys them on kick back, the same diodes from farnell handle it no problem

 

[swervyn]

That would be fine as long as it has sufficient current capacity to operate the relays and LEDs.

One thing not shown is a diode to suppress the inductive transient of the relay coil, which can erode the switch contacts.

Would this be the reason voltage drop was going from 12V to 3V instead of 0V when the switch was pressed ? Because I didnt have a diode across the relay coil?
Off to the local electronics store tomorrow to get a few bits & pieces to test

 

[crutschow]

Would this be the reason voltage drop was going from 12V to 3V instead of 0V when the switch was pressed ? Because I didnt have a diode across the relay coil?

No. The diode is just to suppress the coil inductive transient when the relay is de-energized.
I don't know where the 3V comes from.

 

[Western]

One thing not shown is a diode to suppress the inductive transient of the relay coil, which can erode the switch contacts.
For that, connect a diode (any general purpose diode such as a 1N4148) across the relay coil (cathode to plus).

Just for my own peace of mind ... isn't the diode across the relay coil to prevent potential damage to the coil switching device ... transistor, IC etc ... and for that a 1N4148 would suit ...

... and if the relay is switching an inductive load ... then a diode across the relay switch contacts to prevent arcing and eroding of the switch contacts ... and for that you will likely need a much heavier rated diode.

 

[crutschow]

and if the relay is switching an inductive load ... then a diode across the relay switch contacts to prevent arcing and eroding of the switch contacts ... and for that you will likely need a much heavier rated diode.

True, if the load were a large DC inductive load, but here the contacts are just carrying the coil and LED current, and whatever the control board input takes.

 

[swervyn]

Here's a typical latching DPDT relay circuit:
12V is an external power source.
The "Push to Break" would be the NC limit switch.
The switch light could be connected to pin A.
Pins C and D could go to the wired control terminals.
View attachment 113372

Ok, have this wired as per your drawing and it is working, sort of. The problem I have is that when the push to break (limit) switch is activated it is still possible to press the push to make switch, it doesn't latch but still works in a momentary way.

 

[swervyn]

Seem to have it sorted now, moved limit switch to the 12V feed