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Topper Harley

Hacking the BitChar Cars

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I saw your project of how you took the BitChar car and modded in into the plane. I was wondering what you ended up with on the transmitter. Maybe it was me, but whenever you boosted the power to 9v, things started to mess up and you never returned to how you completed the transmitter. Anything you could tell me would be a lot of help. The rest seems pretty straight forward.

I have a small 49MHz "Thor" car that was just laying around the shop since Christmas and I figured I would give it a shot. The internal wiring based on your tutorial is nearly verbatim, so I think I will be alright on the rest.

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Maybe it was me, but whenever you boosted the power to 9v, things started to mess up and you never returned to how you completed the transmitter.

The 9V RF power mod is documented on the RC-CAM site. It works great, as reported on the project page. Many other folks have extended their Bitcharger equipped airplane's range using the details. http://www.rc-cam.com/microszr.htm

The Pulse Proportional encoder modification had RF related problems and was abandoned. This is discussed on the web page.

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Yes. The success was fully described in the "Update: March 20, 2003" section on the project's web page.

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Alright, I hope these are the last of my questions, but I'm definetly learning a lot along the way.

1. Adjusting the antenna coil. I understand the method of doing it, I just don't see how this will effect the reciever. On this replica of a BitChar car that I have looks like there is a plug of wax in the top of the coil housing. Is there anything significant with that?

2. The LiPo cell. I went to the link you provided and was wondering if the LP550 is what I need to puchase.

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1. After modifying the antenna use a non-magnetic tool and tweak the RF coil for the most reliable long distance range. If there is wax on it then warm it up with a hair dryer to prevent coil damage.

2. The cell(s) you use depends on your motor/prop choice, flight duration, size/weight, and other requirements. I used a LP560 LiPO in my project, which worked fine for me.

Good resource for microsized aircraft and batteries is found here: http://www.rcgroups.com/forums/forumdispla...p?s=&forumid=85

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I have been impressed by this project, and I have started my project with Tyco Hot wheel ($15 at Wal-Mart) and the same plane model form Harbor. (Thanks, bring me to R/C world again after 15years.)

1) I have verifyed the origianl plane flies .... It flew only 5~6m in the beginning, and after several throwing it flied very well. It got higher and hit the roof of neighbor. (crash!) I broke elevator, so need to fix it. Anyway it flies! (50g)

2) Tested original range of TX signal ..... about 10~12 meter. (original had 6v with 4 botton batteries)

3) Modded Tx with 9V battery, 5V regulator, power switch and LED power indicator.

4) Added 60cm ( 2 foot ) AWG36 wrapping wire to the original Rx anntena.

Afer #3 and #4 mods, I got more than 100 meter range. ( I couldn't hear my doughter who had the car.) So this should be enough range to fly this plan in my yard. Then I have ordered Kokam Li-po, motors, started building Li-po charger (LM318 design).

I was almost asking same question about TX mods of throttle control, and found this thread .... so the original idea didn't work well, huh? :huh:

My alternate idea is using forward and Reverse signal to PIC on RX. RX PIC work as ESC. RX's PIC will increase duty when one F pluse received, and decrease duty when one R pulse received. This idea came from very old R/C system with one botton. ( hit once radder goes to right, twice to left)

For example ....

When power up, RX PIC set speed 0 ( duty 0) .

When pressing F once ( send one pluse ) , RX PIC increase to 35% duty

When pressing F one more ( send another pluse ) , RX PIC increase to 70% duty

When pressing F one more ( send another pluse ) , RX PIC increase to 100% duty

When pressing R once ( send one pluse ) , RX PIC decrease to 70% duty

So three consecutive F botton gets full throttle, and three consecutive R botton stop the motor.

Do you think this will work ???

Edited by lovefool

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The stepped throttle idea was discussed awhile back on eZone. You might want to search there to see what came of it.

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I have been looking arounf eZone, and found many post of bitcharge conversion. So far I can't find stepped throttle yet. I will keep looking.

Thanx.

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RC-CAM, I need your advice ....

I have got N20 motor for my SkyRunner. And I tried to use the stock prop for this, however shaft diameter is smaller than prop hole. How can I fill the gap ? I assume even GWS 3x3 has 1mm hole, so too big to the N20 shaft.

Thanx, lovefool.

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I wrapped the shaft with fine thread and CA. After it setup, I applied epoxy and then pressed on the prop. The thread made the shaft a perfect fit into the prop.

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