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go-cart modification, need 2 way radio

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Audioguru should have fun with this post; i am preparing to modify my average and somewhat ghetto go-cart with some simple circuits intended to up it's performance a little bit because my neighbor needs to be put in his place. some of the upgrades include:

1.) A high powered, radio crap fan to help cool the eingine
2.) A set of automatic lights for the front
3.) An LED/voltmeter based speed indicator
4.) A set of various gear ratios to give it a Reverse, Nutral, Lo and Hi. none of which it currently has.
5.) A set of headphones, and mics hooked to 2 LM386 audio amplifiers, so the driver and passenger can here each other over the engine
6.) An electronic ignition system (this is'nt too hard, i'm just going to remove one from a similar sized lawn-mower)
7.) this is the one i am haveing a little trouble with, a 2 way radio that is linked to the mics in the headsets that will send a signal back to a fixed location. i want the send to be activeated by a button, and i want the receive to be active as long as the power is on.

I was hoping that audioguru might be able to help with the transmiter and receiver. i was going to use his FM transmiter, but i was slightly unsure of whether or not the transmiter could be bumped to something like 20MHz.

I will be posting my schematics after i have finished them, the firs is most likely going to be the fan. feel free to comment on them and sugest improvements to the circuit to enhance performance, or reliability.
 

tcmtech

Banned
Most Helpful Member
Well first off what type of engine do you have?
How good of fabrication and hands on mechanical skills do you have?
What does your engine have for a electrical power source?
 
the engines is 5 hoarse power. it's the same as a small tractor engine, that's why i thought that an electrical system from an old mower would be a good idea. i don't need to have good mechanical skills, i have people that do that for me :) (what they don't know is that i should pay them). it will take some time to work the electrical system in.

here is the schematic for the speed indicator, this is just a rough idea, in a later design the 741 will be replaced with a higher end op-amp.
 

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gary350

Well-Known Member
You can put some alcohol in the gas or run on 100% alcohol or alcohol with 2% water they will all make the engine run cooler. Gasoline is formulated to have as much as 8% water in it during the summer (hot weather) it makes the engine run cooler and it gives better gas mileage because when water turns to steam. Water volume increases 1600 times when it turns to steam that is a lot more than gasoline.

What is the purpose of all these gizmos on your go cart? Are you just having fun?

Here is a pic of my go cart it has a 4 cylinder mercury outboard boat motor power head on it. The engine is 65 HP stop producing about 75 hp at 7200 RPM running on 90% gas plus 10% alcohol. The engine is water cooled using 2 heater cores from junk yard cars as radiators and a Toyota water pump belt driven off the rear axle. Disc brakes and positive traction. Gear ratio is 3.7 to 1 direct drive with #40 chain. It idles at about 5 mph and will reach top speed 87 mph in about 3 seconds. Total weight of the entire go cart is 218 lbs. G force is unreal I have to accellerate in the curve with 1 eye closed because the G force causes my eyes to cross. Punch the gas pedal to the floor you better be handing on tight G force will pull your hands off the stearing wheel. This is the most fun toy I have ever built.

**broken link removed**
 
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tcmtech

Banned
Most Helpful Member
If you are using a 5 hp lawn and garden engine there should be no need for a electric fan. They do just fine on themselves.
As far as for a transmission I built a go-cart for my niece that just uses a stock riding lawn mower trans-axle. Being its a low power application I just changed the input pulley to a smaller one so it spins the transmission faster to get better ground speed.
 
You can put some alcohol in the gas or run on 100% alcohol or alcohol with 2% water they will all make the engine run cooler. Gasoline is formulated to have as much as 8% water in it during the summer (hot weather) it makes the engine run cooler and it gives better gas mileage because when water turns to steam. Water volume increases 1600 times when it turns to steam that is a lot more than gasoline.

What is the purpose of all these gizmos on your go cart? Are you just having fun?

Here is a pic of my go cart it has a 4 cylinder mercury outboard boat motor power head on it. The engine is 65 HP stop producing about 75 hp at 7200 RPM running on 90% gas plus 10% alcohol. The engine is water cooled using 2 heater cores from junk yard cars as radiators and a Toyota water pump belt driven off the rear axle. Disc brakes and positive traction. Gear ratio is 3.7 to 1 direct drive with #40 chain. It idles at about 5 mph and will reach top speed 87 mph in about 3 seconds. Total weight of the entire go cart is 218 lbs. G force is unreal I have to accellerate in the curve with 1 eye closed because the G force causes my eyes to cross. Punch the gas pedal to the floor you better be handing on tight G force will pull your hands off the stearing wheel. This is the most fun toy I have ever built.

**broken link removed**

your go cart sounds pretty BA. if posible i would like to see a video of it.

tcm: true you don't really need a fan for the engine, but the thing is that my neigbor doesn't know that. he thinks his go cart is better because it has as a 'front suspension' and "safety features". it doesn't matter though, he needs someone to put him in his place. i can't seem to explain to him that the exktra 50lbs or what ever the roll cage weighs, is making it slower. when i put the electrical system on, he won't know what any of it does. so only half the board is going to be functioning, the other half is going to be made up of useless parts that have been destroyed in one way or another. just to make an impression.
 

tcmtech

Banned
Most Helpful Member
I see. The neighborly go-cart competition! As far as speed the small engine stuff is more engine governed than physically limited. My cousins had a go cart years ago and it didn't matter if one Little runt was driving or if all four of us where piled on it. We still got to the end of the driveway in the same time. The big boy higher end ungoverned stuff is where the weight makes more difference.
 

BrownOut

Banned
gary350: I read your post, and all I can think of is the "Darwin Awards." Sorry, I couldn't help it :) Please try to be safe.
 
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yea, my neighbor is the kind of person that always has to be first. if it comes down to it, and he says that his go cart is still better even after i makr these changes, i'm just going to have my little brother ride shotgun, give him the paintball gun and say go to town.
 

tcmtech

Banned
Most Helpful Member
If you really want him to go nuts get the high RPM connecting rod and piston for those high performance go carts anduse a heavier spring on your governor so yours rev limits at around 8000 RPM then tell him to do the same (but without the internal changes.).:D The 10 -15 HP your little 5 will put out and the ripping blast will shut him right up! ;)
Then put the lights and other accessories on it too!
Just for a thought you could pick up some of those cheap digital LED voltmeters on eBay and modify them to work as a digital RPM meter and speedo as well! Just feed them with a frequency to voltage IC and give them the right power source.
$30 and a few hours time and you have more things to show off.

Its just a thought.:)
 
that's a real good way to shut him up. I'll take great joy in watching him come back crying that mine is still better even though he did exactly what i told him to. the fan is just for aesthetics. the radio is a practical application though, i think that audioguru said that his MOD4 worked better than MOD3. what i want to do is bump the frequency below or above the FM band so i don't need to worry about a crap load of RF interference. they don't need to transmit very far, a quarter of a mile should be far enough. my curiosity is in trying to get the output of a 386 to feed into the transmitter so that the audio will be boosted, if possible, if not it's no big deal. i also would like a good reliable FM receiver. Maybe something with a crystal. i have looked on Google, but all of the circuits either have an AM or FM function which is not what i want, or they don't seem like they would even work at all.

here is a link to the website where i got most of my RF circuits Audioguru: if you even look at this post plz help.
RF circuits

Below are some of the circuits that i have been looking at. here is the reviver that i have shown some interest in:
342-Regenerative_FM_Receiver.gif
 

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Hero999

Banned
The gearbox sounds like the hardest part.

What sort of transmission does it currently have?

Is it just a centrifugal clutch and a fixed ratio transmission?

If it's a CVT then I suggest leaving it alone because it'll already give better performance than a manual transmission will.

If it's a fixed ratio transmission then maybe you could upgrade to a CVT from a scooter? I'm afraid I can't help you much with this one.

As far as the radio is concerned, you could use audioguru's circuit and a standard broadcast receiver. If you're worried about getting into trouble then maybe you could modify them both to use a free frequency.
 
currently it has no transmition, but i have done some work in the past with a minibike transmition on an older go cart. that worked for about a week untill it gave out. i'm guessing that it was due to mettal fatigue. probably shouldn't have used a transmition from the 60s
 
still waiting for audioguru. i have made the receiver i posted in multisim, it worked great untill i added the audio to the RF, then it just craped itself. I am kind of leaning twards just buying a receiver and modifying it to tge frequency i want.
 
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