Stumped by a 2CH RF relay

[Yeoman]

I picked up a 2CH relay/receiver to remotely operate a 12v DC in forward and reverse. This receiver Is prewired with +/- input wires and 2 sets of +/- output wires. There are no options to do my own wiring using NO/NC/COM wiring.
I have synced the relay/receiver and am able to activate 12v on each channel. Problem is both grounds coming out are always grounded at all times and I can’t figure out how to send + charge to each of the motor leads to reverse operation.
Is there a workaround for this without adding components or do I need a more traditional receiver with NC/NO/COM options?

 

[Pommie]

Use a dpdt relay on one channel to reverse the motor and the other channel to turn it (the motor) on/off.

Mike.
Edit, what current can the module handle and what current does the motor need?

 

[Yeoman]

It’s a 3amp motor and 5 amp module. However, the motor amps could surge to 10 amps under maximum load so I know I have a weakness there but the application isn’t critical.
With the DPDT switch, wouldn’t I have to manually throw that switch to activate reverse direction? I’ll be 60’ from this setup.

 

[Nigel Goodwin]

It’s a 3amp motor and 5 amp module. However, the motor amps could surge to 10 amps under maximum load so I know I have a weakness there but the application isn’t critical.
With the DPDT switch, wouldn’t I have to manually throw that switch to activate reverse direction? I’ll be 60’ from this setup.

He said relay, not switch - use the existing single pole relay to trigger the DPDT relay, and use it's contacts to reverse the motor - so that channel becomes forward/reverse, and use the other channel for on/off.

 

[Pommie]

If the motor takes that much current then use two relays, one for on off and one to reverse it. If the module is solid state then the start current (same as stall current) from the motor may burn it out. Do you have a link to the module?

Mike.

 

[Yeoman]

Module off EBay. https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/271222059125

Since it appears I would need to add/purchase additional components (DPDT relay), I think I’ll order a module I can custom wire for this setup and keep this module for some future purpose. Thanks

 

[Yeoman]

He said relay, not switch - use the existing single pole relay to trigger the DPDT relay, and use it's contacts to reverse the motor - so that channel becomes forward/reverse, and use the other channel for on/off.

He did say relay didn’t he. Thanks for the clarification.

 

[Diver300]

I suggest buying two SPDT relays & running one from each channel, so one gives forward and one reverse.

 

[Pommie]

I suggest buying two SPDT relays & running one from each channel, so one gives forward and one reverse.

And, if he pushes both buttons at once?

Mike.
Edit, I'm thinking you can feed each relay from the others NC contacts and that would fix any firework effect. To late to work out in my head.

 

[Diver300]

And, if he pushes both buttons at once?

Mike.
Edit, I'm thinking you can feed each relay from the others NC contacts and that would fix any firework effect. To late to work out in my head.

If it’s wired correctly, like an H-bridge, if both. (Or neither) relay is energised, the motor is shorted, and the supply isn’t.

 

[vu2nan]

The contacts of two external relays K1 & K2, energised by the two receiver relays, could be configured as a 'H' bridge to run the motor in either direction.

The coils of K1 & K2 are to be interlocked to prevent both coming on together.

It goes without saying that a separate on/off relay would not be required.

 

[Pommie]

Missed the "S" in spdt. I blame lock down, beer and wine.

Mike.

 

[Nigel Goodwin]

The contacts of two external relays K1 & K2, driven by the two receiver relays, could be configured as a 'H' bridge to run the motor in either direction.

View attachment 124423

The coils of K1 & K2 are to be interlocked to prevent both coming on together.

It goes without saying that a separate on/off relay would not be required.

It's a lot safer to use a second on/off relay, and a single DPDT for forward/reverse - and a lot simpler than trying to create an interlock scheme with two independently controlled SPDT relays controlled from separate channels.

Even in use the difference is like driving a car, or driving a tank

 

[vu2nan]

It's a lot safer to use a second on/off relay, and a single DPDT for forward/reverse - and a lot simpler than trying to create an interlock scheme with two independently controlled SPDT relays controlled from separate channels.

Even in use the difference is like driving a car, or driving a tank

Hi Nigel,

Thank you very much for your suggestions.

In hindsight, it appears that I have presumed a requirement/function and focussed on ease of operation based on that.

The presumption is that the remote buttons are programmed for 'inch' operation, i.e. 'press and hold' to run and 'release' to stop. In this application, that would translate to 'press and hold button 1 for motor forward and release to stop' and 'press and hold button 2 for motor reverse and release to stop'.

Regards,

Nandu.

 

[Nigel Goodwin]

Hi Nigel,

Thank you very much for your suggestions.

In hindsight, it appears that I have presumed a requirement/function and focussed on ease of operation based on that.

The presumption is that the remote buttons are programmed for 'inch' operation, i.e. 'press and hold' to run and 'release' to stop. In this application, that would translate to 'press and hold button 1 for motor forward and release to stop' and 'press and hold button 2 for motor reverse and release to stop'.

Perhaps you've presumed correctly? - but still got the issue of pressing both buttons.

Depending on his specific receiver as well, it 'may' be configurable to latch or not, or even toggle on alternate presses.

 

[KeepItSimpleStupid]

I have synced the relay/receiver and am able to activate 12v on each channel. Problem is both grounds coming out are always grounded at all times and I can’t figure out how to send + charge to each of the motor leads to reverse operation.

In reality, normally grounded is the right way to go. That brakes the motor.

The end of the normally grounded both sides motor, one side gets 12V thus fwd and reverse and brake,

 

[Yeoman]

By golly I think you’ve got it. Thanks. I’ll give it a try tomorrow.

 

[vu2nan]

Here's my new version thanks to all your inputs.

Two external relays K1 & K2 are to be energised by the receiver relays.

The motor would be off and braked with both K1 & K2 being simultaneously off or on. Hence no interlock between K1 & K2 would be required.

- Nandu

 

[KeepItSimpleStupid]

Nice!

There's really 4 states for a DC motor: cw, ccw, brake and coast, but not with that circuit.
Brake can be broken down into brake and regenerative brake.
Limit switches add another level of complication. The limit switches have to be able to withstand the relay coil current.
Automotive type relays are used a lot in this application and the coil currents are quite high.

 

[Yeoman]

Vu2nan’s circuit drawing is I believe what you (Keepitsimple) theorize may be my module’s setup. Is that right? If so, could it be my motor did not reverse when my two + connections were used as motor inputs was because I was in toggle mode and left K1 energized when I energized K2? I guess I’m thinking my prewired module is setup like this?