newbie needs answers

[-=CrAnSwIcK=-]

here's a situation i need resolved...*edit* one power source */edit*, two DC motors connected to one drive shaft...the input to the main motor is variable, and the secondary motor free spins with no current going through it, i want the secondary motor to be switched on when, and only when the main motor is near or at its max operation and act as a 'turbo' for the drive shaft, and then at maximum current, have both motors running at max, and when the current is reduced, the secondary motor turns off and the main motor runs alone once again...and i need the value of the 'turbo activation' to be adjustable...power sources is 6 AAA batteries, or a single 9v...also somone told me that the free spinning secondary motor will act as a generator, if this is true, is there a way to store the current that's being generated by the secondary motor, and then send it back around the circuit to compliment the source once the secondary motor is engaged?

for the why's, it's for a remote controled car...and the answers i'm looking for are: is it possible, is it practical, how complicated will it be, and what types of components will i need to make this work? I have very basic knowledge about electronics...though i have been accepted to the airforce to do this type of thing for a living, for the time being, i'm pretty much clueless...but i want to further my understanding of how circuits can be created to perform certain tasks...thanks

 

[Leftyretro]

Doesn't sound like a practical idea to me.

If you could find a proven design that works and can post it's schematic drawing then maybe we could comment on possible improvements to it.

Just running two identical DC motors in tandom doesn't increase the speed (RPMs) of the common shaft just the torque value, so maybe it could help on climbs but won't change max car speed.

Now if the two motors are not identical (different max RPM & wattage) then you would need some kind of over-rideing mechanism to allow the stronger motor to take over, tying them mechanically together doesn't sound like it would work to me

As far as a secondary motor when not driven, being used as a generator, forget it, losses would be greater then any practical power recover, at least that's my first impression.

Lefty

 

[Pommie]

If the 2 motors are identical then just connect then in parallel and they will behave exactly the same as the system you describe above. In fact they will perform better as the main motor will run hotter in the complex system.

Mike.

 

[JimB]

As far as a secondary motor when not driven, being used as a generator, forget it, losses would be greater then any practical power recover, at least that's my first impression.

You have just described one of the classic perpetual motion machines!
It wont work.

JimB

 

[-=CrAnSwIcK=-]

the generator thing is something someone told me, i wasn't sure...ok, so now what if both motors were working together in parallel, then have some sort of switch that when a certain amount current is exceeded a second, higher voltage power supply is initiated through a different set of FETs, and make both motors reach a higher RPM...

I do have two indentical radio transmitters and receivers, with different operating frequencies, but the one circuit board ended up in a puddle (i wasn't driving) so only the steering servo works, could i somehow use these to aid me, with perhaps a radio controlled switch?? i figured since i have spare parts, maybe i could jimmy rig something that way...

 

[Leftyretro]

the generator thing is something someone told me, i wasn't sure...ok, so now what if both motors were working together in parallel, then have some sort of switch that when a certain amount current is exceeded a second, higher voltage power supply is initiated through a different set of FETs, and make both motors reach a higher RPM...

I do have two indentical radio transmitters and receivers, with different operating frequencies, but the one circuit board ended up in a puddle (i wasn't driving) so only the steering servo works, could i somehow use these to aid me, with perhaps a radio controlled switch?? i figured since i have spare parts, maybe i could jimmy rig something that way...

Well if you had an available higher voltage source why not use it as the main and only motor voltage all the time and just let the speed controller (throttle control) do it's thing.

I guess if your basic goal is to make the car go faster then things like stronger motor, different gear ratios, higher voltage, less weight, more streamlining, etc would be where I would look.

Lefty

 

[-=CrAnSwIcK=-]

yes those things are very normal though, i'm looking to do something that not everyone else is doing, and then comparing the two...and the main idea is to perform as if it were almost stock, so it's easier to control in confined areas...and then activate like a "nitrous boost" effect when the throttle is pinned...that's all...plus the extra motor and stuff looks cool, cause it's front mounted and has a slick heat sink so when you pop the hood(another project...*sigh*), it sorta has an "engine" look to it, but also have a practical function...i was just toying with an unconventional idea...thanks for the input...

*edit* Ok, so far you guys have answered a few of my questions but not the main question i had...which was, can i have threshold voltage activated switch that sends a 9v current to two motors while the main circuit board still runs on 6v...perhaps 6x1.5c AAA would be best for this...yes or no, and what do i need...i can research myself so parts and tut links would be very helpful, thanks again...cheers

 

[-=CrAnSwIcK=-]

someone suggested this to me, looks simple enough...

**broken link removed**

 

[Leftyretro]

someone suggested this to me, looks simple enough...

**broken link removed**

Looks pretty hopeless to me. Looks to me that when the secondary battery is switched in the motors will turn in reverse! That's not what I would call a turbo mode

Lefty

 

[-=CrAnSwIcK=-]

*edit*ok, i think i got the terminals reversed in the secondary power supply, and maybe if the positive side of the secondary power should be connected straight to the positive side of the battery, not the negative......can you fix this for me...the diode should keep it from going turbo in reverse, but the relay should only switch on in forward drive...*/edit*

remember someone suggested this to me, and i drew the schematic in MSpaint based only on the method described to me and a glossary of circuit schematic symbols...i'm no expert, i could have drawn it wrong...but with the changes i mentioned above, could this be done??