2 potentiometers controlling one throttle
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Printed Date: May 13, 2025 at 6:36 PM
Topic: 2 potentiometers controlling one throttle
Posted By: cummins06td
Subject: 2 potentiometers controlling one throttle
Date Posted: October 22, 2012 at 5:01 PM
Thanks in advance for taking the time to help me with my problem. I have a Mack diesel field mechanics truck that has a crane and air compressor on it for air tools. The crane and compressor have the option to idle up the engine with the flip of a switch. It has an electronic accelerator with a potentiometer on it to control the engine rpm. I would like to add an additional potentiometer for the engine idle up. If I use two pots on one reference circuit to computer will i do damage to the pot that is not in use by voltage feedback onto the referance side? If so is there any way I can make this kinda setup work so i can just flip the toggle switch and make the engine idle up to a specified rpm based on the second pot? The feed voltage to the pots is 5 volts so i was going to use a relay to control power to the second pot, flip the switch and it'll activate the relay allowing 5 volt feed to second pot and which would idle up the engine. Any thoughts or comments would be greatly appreciated. Thanks again!
Ryan
Replies:
Posted By: lurch228
Date Posted: October 22, 2012 at 7:14 PM
Yes you can as long as you isolate the 2 from each other. Use a relay to add the pot in to bypass the original. Wire it so original goes to 87a (NC), new pot to 87 (NO), output to computer to 30, 85 to ground, 86 +12v from toggle switch. Any 5 pin 10amp or larger relay should work.
Posted By: i am an idiot
Date Posted: October 22, 2012 at 8:11 PM
Supply both pots with 5v and ground. Connect the wiper of each pot to the outside terminals of a Single Pole Double Throw on-on, or an on-off-on toggle switch. Wire the center terminal of that switch to the computer. You do not need a relay at all.
Posted By: lurch228
Date Posted: October 22, 2012 at 9:44 PM
i am an idiot wrote:
Supply both pots with 5v and ground. Connect the wiper of each pot to the outside terminals of a Single Pole Double Throw on-on, or an on-off-on toggle switch. Wire the center terminal of that switch to the computer. You do not need a relay at all.
This would work too as you would still be isolating the two pots from each other as I said originally. But he asked how to do it with a relay for his setup. So that is what I told him! He already has one switch, if he does it your way it would be best to replace the current toggle with a on-on-off switch simular to the on-off-on one you suggested if it's a single switch currently(if feasiable). If it's a on-off-on switch already and the other side isn't used then he wouldn't need any new switches. Just would need to connect to the open terminal and wire pot to ground.
Posted By: lurch228
Date Posted: October 22, 2012 at 10:03 PM
If you need to replace the current switch the a SPDT is the way to go. You get a staged idle up that way. This is just one brand of switch you can use (Carling Technologies 2GG51-73 Toggle Switch SPDT 15A Off/1 On/2 on).
Posted By: cummins06td
Date Posted: October 23, 2012 at 8:30 AM
Thanks for your help guys. I think it'll be easiest for me to use a relay in the situation due to the fact that i have an idle up switch on the crane controller and the compressor has an internal idle up switch(when air pressure is low it idles up engine to build air faster). both of the idle up circuits go to a relay board and then have one output to the computer to idle it up. Thanks again!
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