HI,

I just put together a 12 volt circuit to test adding another pot for throttle/speed ajustment on a motor.

Ohms law applied to the parallel circuit cuts the amperage/current across the visible resistor, in this case the variable resisors/potentionmeters. Have to have both pots all the way open to get 12 volts on the motor.

However, If i exchange the pot for pot with an on off swtich,and turn on the pot to ''off''... does the resistance get masked or no longer applly in the circut?

So that the other pot that is one gets al the current or amperage?

Another way to put it, of a potentionmeter with a pot that has a real on and off switch integratred, in the off potition subtract le resistance from the equation?

Im pretty sure I can use rocker switch on-off-on to isolate both pots, but the client doesnt want another switch in this circut.

 

Your description leaves out a lot of necessary information. Can you show us a circuit diagram?

 

the 2 pots are in parallel... so I need to hide one pot or the other to get full voltage/amperage. Im thinking b100k with on/off switch..to replace both pots. I just sont know that when in off position, that the resistance disapears from the circuit or so to speak, to all voltagte and amperage gos to the other pot that is ''on''.

 

Your diagram does not show how the second potentiometer and switch are wired. "Wired in parallel" is a very ambiguous term for a three terminal device. You know what you mean but I don't.

 

Your diagram does not show how the second potentiometer and switch are wired. "Wired in parallel" is a very ambiguous term for a three terminal device. You know what you mean but I don't.

In the actual picture of the circuit you cam zoom 8m to see the connectors I used from a dpdt switch to connect them in parallel..

the diagram is only for the 12 volt motor controle.... The modification or need is to use 2 pots to controlr the throttle of one motor. Series wont work.. In parallele, only if I can ''hide'' so to speak on the the pots. Either I use a switch which is last resort or use a pot with an on/off integrated .. Just wondering if you guys who know electronics more that I do would have a solution. or if I am on the right track.

 

Please show the pot and switch connections on your circuit diagram.
Schematics are the language of electronics, not a picture of a wiring layout.

 

When I zoom in on your picture, there is not enough resolution to see where all the wires go. They are all laying on top of each other. Can you please show the connections on your schematic.

 

Please show the pot and switch connections on your circuit diagram.
Schematics are the language of electronics, not a picture of a wiring layout.

this is the best I can do

 

Pots with a built-in switch normally have no physical connection between the switch and the resistive element.

If I understand correctly what you want to do you will need pots with 2 SPST switches to prevent interaction between the two.

 

I might have a better chance of guessing how they are wired if I knew why you are trying to add a second potentiometer. What exactly are you trying to achieve?

 

Pots with a built-in switch normally have no physical connection between the switch and the resistive element.

If I understand correctly what you want to do you will need pots with 2 SPST switches to prevent interaction between the two.

i want to eliminate on of the pot on the circuit so I do not have a split with the current... Im pretty sure this will work if I go with 2 circuts and a dpdt switch, but that is last resort.

If a pot has an on and off switch.. When in off position does its resistance on the circut go down to zero ? .. So thats OHM law doesnt affect the other pot. Meaning all the curent/voltage wil go tot he other pot?

 

I might have a better chance of guessing how they are wired if I knew why you are trying to add a second potentiometer. What exactly are you trying to achieve?

trying to control a 23 hp motor that uses on pot... I need to add another pot so I can control it either from the cab of the truck or from the back of the truck.... Client does not want or accept as a last resort a rocker switch dpdt.. 2 pots in parallel, however ohm law and circuits in parallel devide the curent over the resistors... If the pot in off position cut the risistance from the curcut than the other pot gets all the curent.. That what I am trying to figure out .. That is why I can to this forum...

 

I need to add another pot so I can control it either from the cab of the truck or from the back of the truck.... Client does not want or accept as a last resort a rocker switch dpdt..
...................
That what I am trying to figure out

Okay, now that you finally stated what you need the two pots for, we can better help.

I see no way around having a switch (or relay) to select either one or the other of the pots to control the motor.
If you want to be able to control the switchover from either the cab or the back of the truck, then you could use a latching relay, and two momentary switches, one in the cab and one in the back, to latch the relay and connect to the pot that will do the controlling.
I can post a circuit for that, if you like.

 

Okay, not that you finally stated what you need the two pots for, we can better help.

I see no way around having a switch (or relay) to select either one or the other of the pots to control the motor.
If you want to be able to control the switchover from either the cab or the back of the truck, then you could use a latching relay, and two momentary switches, one in the cab and one in the back, to latch the relay to connect to the pot that will do the controlling.
I can post a circuit for that, if you like.

ok...so the pot with on and off switch wont work .... any exmaple of a latching relay thats simple to instal and use.. and thanks again a gratly appreceate your help.

 

ok...so the pot with on and off switch wont work .... any exmaple of a latching relay thats simple to instal and use.. and thanks again a gratly appreceate your help.

yes ..please i would appreceate a circuit that allow to control one mortoe with two pot with a relay or simple controller between the two.. The cloient juste wants one pot in the cab and one pot in the back.. the controller or relay can be hid with the rest of the wiring for the support fire truck vehicle.

 

i want to eliminate on of the pot on the circuit so I do not have a split with the current... Im pretty sure this will work if I go with 2 circuts and a dpdt switch, but that is last resort.

If a pot has an on and off switch.. When in off position does its resistance on the circut go down to zero ? .. So thats OHM law doesnt affect the other pot. Meaning all the curent/voltage wil go tot he other pot?

No, because as I stated the switch on a pot does not have any physical connection to the resistive element, you have to wire the switch into the circuit the way you want.

2 pots with SPST switches will work as you need. (assuming only one pot is switched on at a time) If you want to override the other pot from either pot then this won't work.

If I was at my other machine I could show you how.

You basically need to intercept the connections between the two legs of the resistive element and the two diodes, while leaving the wiper connected.

 

In order to have full control of the motor speed using two potentiometers in the circuit you show, you will need to have a switch that connects the slider of one potentiometer or the other to pin 3 of the 555, with the outer connections of the potentiometers connected in parallel.
One simple way of doing it would be by using a potentiometer with a built-in switch. The switch would need two extra wires added between the remote control and the controller. The switch could could then activate a small, low power 12V relay with one single pole, double throw contact. The contacts could then connect either the local or remote potentiometer slider to the controller.
I hope this helps.

 

There may be a problem with the solution I posted, depending on the requirements. The choice of local or remote control can only be made from the remote control station. To make it selectable from either remote or local station would make it somewhat more complicated.
For the solution shown, you would have to either use two 200K pots or double the size of the 10nF capacitor to maintain the same switching frequency of the circuit.

 

trying to control a 23 hp motor that uses on pot... I need to add another pot so I can control it either from the cab of the truck or from the back of the truck.... Client does not want or accept as a last resort a rocker switch dpdt.. 2 pots in parallel, however ohm law and circuits in parallel devide the curent over the resistors... If the pot in off position cut the risistance from the curcut than the other pot gets all the curent.. That what I am trying to figure out .. That is why I can to this forum...

Here we have another example of only getting a very small part of the picture because the Thread Starter has already determined that what we are shown is the only place where there is need for help.
But at this point we learn that the project is to control the speed of a 23 HP motor that is part of some mechanism on a truck. And that there exists, possibly already, some sort of speed controller for that motor (I am guessing about that part.)
At this point it is clear that the solution is not simple, and that this is not a hobby type of project.
So here is another guess: There are two locations where speed control is desired, one inside the truck, and another speed control outside, at a location where whatever the action being powered is, so that the speed of the action powered can be observed and controlled. The question is how to have the speed control available at two locations.

Question #1: Does there also need to be a means to switch the motor on and off from both locations?
Question #2: Is speed control from one location at a time acceptable? (only one location at a time being able to control the speed.
Question #3: Does the Thread Starter know and understand the resistance of the existing speed control potentiometer ?
Question #4 Is it acceptable for the speed to be set at one location and then to be changed from the other location?

I have the detailed control scheme all worked out in my head, where from either location the drive can be switched on and the speed set, with the other location having no control of speed or ON/OFF. A master switch would be located at the inside position to disable the motor operation from either location. That is a mandatory safety function.

 

Here we have another example of only getting a very small part of the picture because the Thread Starter has already determined that what we are shown is the only place where there is need for help.
But at this point we learn that the project is to control the speed of a 23 HP motor that is part of some mechanism on a truck. And that there exists, possibly already, some sort of speed controller for that motor (I am guessing about that part.)
At this point it is clear that the solution is not simple, and that this is not a hobby type of project.
So here is another guess: There are two locations where speed control is desired, one inside the truck, and another speed control outside, at a location where whatever the action being powered is, so that the speed of the action powered can be observed and controlled. The question is how to have the speed control available at two locations.

Question #1: Does there also need to be a means to switch the motor on and off from both locations?
Question #2: Is speed control from one location at a time acceptable? (only one location at a time being able to control the speed.
Question #3: Does the Thread Starter know and understand the resistance of the existing speed control potentiometer ?
Question #4 Is it acceptable for the speed to be set at one location and then to be changed from the other location?

I have the detailed control scheme all worked out in my head, where from either location the drive can be switched on and the speed set, with the other location having no control of speed or ON/OFF. A master switch would be located at the inside position to disable the motor operation from either location. That is a mandatory safety function.

HI,

My name is stephane..

Sorry if the what was written initially was vague..

The motor is a vanguard 23 hp (efi)
https://www.vanguardpower.com/na/en...tal-shaft/vanguard--230-gross-hp-efi-etc.html

There is no need to turn on or off the motor from both locations

The existing knob/potentiometer resistance is : 5252 ohm or 5k

For question 4 .... This is a motor that will be attached to a water pump for fires. Will either be controlled form the back of the truck or from inside the cab..

Hope the answeres help and a thanks to everyone who offered help.