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Old Nov 26, 2002, 07:55 PM
Sticky Shepherd
Graham Stabler's Avatar
Oxford/England
Joined May 2001
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Bitcharger conversion

I have started this thread so we can work out some basic details of how to convert a bitcharger type car (including IR types) to a workable indoor model.

Issues to discuss?

Increasing the range of the TX

Improving the speed control (i.e. add a mosfet)

Use of the motor/gears and props.

Using supplied coils/homebrew actuators.

Other stuff.

I just think that if we can prove the concept properly with some stick model or other and a stock tx/motor then the contest and our fun will be improved.

Feel free to repost useful stuff from other threads here, use this as a storage box and start seperate threads for general discussion of the various issues.

Graham
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Old Nov 27, 2002, 02:57 AM
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London, UK
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G,
there seems to be a lot of options around in terms of what cars to use as the start of a project like this. How about a no brainer recipe book as to what is the minimum required for reasonable success?

eg: Take one BitCharg car. Remove components x, y and z.
Take plans provided by a helpful aeronut, add li poly of certain capacity, suitable didel power plant and gear box (all from Mr Stabler) mix according to a certain diagram, leave for 2 mins to let the glue cool and then have fun in a large room.

I think it can be so easy to get on the first rung of the ladder (a klutz like me has shown this to be true) especially with an idiot list like this. It saves having to make the call as to which components to choose and how to bung 'em together in the best way. For exmaple when Dr Chris did his 1 cell IR articles in Model Flyer I quite liked the idiot list in choosing the right power plant and prop. V helpful.
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Old Nov 27, 2002, 05:47 AM
Sticky Shepherd
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Oxford/England
Joined May 2001
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Fast bloke, thats the idea of the thread, work out the basic details then people can concetrate on models for the contest. The fact is I don't have a full recipe for sucess yet.

Mario, please keep to the thread topic which is working out the basics of using these things.

Graham
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Old Nov 27, 2002, 05:54 AM
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Brunswick, Germany
Joined Nov 2002
104 Posts
Facts first

Hi folks,

I only heard of the Microsizers/Cloes conversion thing three days ago, and it keeps fascinating me. I just ordered some to slaughter

The thing I still miss in the discussion about converting the innards to a plane are the "hard facts" about this electronics details. I have a lot of questions and hope that someone already ran some tests about :

What is the voltage of the Motor and steering coil output ?
How much current can they handle before they fry ?
Is there a internal voltage booster or does the electronics run on 1,2 V ?
How much power draws the standard motor under the usual conditions ?
Does every transmitter have this "cripple condeser" thing ?

If I increase the Transmitter volage, what happens ?
If I just increase the Reciever voltage, what happens ?

What is the current of the Transmitter attached charging device ?

OK, many questions for the moment, I hope to answer some basic questions with your answers, for example the most important one : Will a plane fly if I just put all the components into a small plane, or will it suffer from a lack of power ?

Patrick Wegener
Team Klaustrophobia, Braunschweig, Germany
www.unisport.tu-bs.de/~modellflug

P.S. Hi epilot, nice to see you back (and all the other folks of the SFRC Mailing list two years ago...)
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Old Nov 27, 2002, 06:31 AM
Thats NOT indestructible
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OK

I am writing this in an IT lession with the risk of detention, so i will be brief

I have compiled a list of useful links for these cars, inluding shops here in the uk, and mod sites

http://www.bitchar-g.co.uk - reviews and cars

http://www.cflowers.freeserve.co.uk/mike_index.htm - mods (lighting etc)

http://tinyrc.com/ - Forum etc (includes Transistor mods and everything (i think it also has RX cripple cap mod)

http://tinyrc.com/qfm/racing/index.htm - Cool mods (including Cripple cap)

http://www.rcgroups.com/forums/showt...threadid=74136 - Comp

http://www.rcgroups.com/forums/showt...threadid=72014 - Proportional mods

http://www.rcgroups.com/forums/showt...threadid=45121 - More on Proportional mods

http://www.rcgroups.com/forums/showt...threadid=73275 - THE thread

http://www.rcgroups.com/forums/showt...threadid=73520 - Plane with BCG RX

http://www.ausmicro.com/index.asp - Loadsa mods with piccies (tecnical stuff)

I will update this when i find more stuff

Josh
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Old Nov 27, 2002, 09:31 AM
Sticky Shepherd
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Oxford/England
Joined May 2001
4,017 Posts
Re: Facts first

Hey Patrick I'm a big fan of yours! My first ever indoor model was a Klaustophobia (by Martin Kopplow?), not a complete success but great fun.

Anyway,

>What is the voltage of the Motor and steering coil output ?
>How much current can they handle before they fry ?

These are the same as the battery voltage less a bit for the volt drops over the transisters. Perhaps I should state this first hard fact. IMHO we need to be using 145mAh Lithium polymer cells. The board can handle it without trouble as I prove by driving my car powered by one. The speed control is pretty poor, epilot has shown that adding an external mosfet is probably a necessity.

>Is there a internal voltage booster or does the electronics run on >1,2 V ?

No booster

>How much power draws the standard motor under the usual >conditions ?

not a lot.

>If I increase the Transmitter volage, what happens ?

I have seen a tx fitted with three cells on the web, it should improve range.

>What is the current of the Transmitter attached charging >device ?

Not sure but I'm not sure it matters, the origional cells are probably little use.

>Will a plane fly if I just put all the components into a small plane, >or will it suffer from a lack of power ?

No you need more voltage for the motor.

Graham
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Old Nov 27, 2002, 09:42 AM
Thats NOT indestructible
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I have read that if you do the following you can get a range of like 120', way more then enough:

1) Remove the Cripple cap if the tx has one (newer ones)
2) Remove the Cripple cap if the rx has one (one one newest car)
3) Use 3-5 cells in the tx
4) Use telescopic ariel on the tx (like 2 foot)
5) Use longer ariel on the rx (like 10 cm)

All of the above mods can be found at
http://tinyrc.com/qfm/racing/index.htm (except for the 3-4 cell one)

Josh


P.S. I am thinking of getting a couple of these cars from toyeast.com (the LXX car). Anyone in the UK wanna split shipping or somthing?
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Old Nov 27, 2002, 09:51 AM
Sticky Shepherd
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Good links Josh, just got back from some surfing.

You can increase the volts to the TX to upto 5v. So 3-4 cells will do the trick. I might try a big lithium cell.

I'm currently trying to work out which is the cripple capacitor on my TX and then will try to determine if removing it helps.
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Old Nov 27, 2002, 09:59 AM
Thats NOT indestructible
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London UK
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There are some nice pics of how to remove it here :

You might wanna desolder it, so you can put it back if you have ne probs

http://www.ausmicro.com/technical/bi...-mod/index.htm

Any idea on Transistors, i have not done them you in physics, and my dad who is an ee has not seen one for like 20 years!! (he never liked analogue)

Josh
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Old Nov 27, 2002, 10:21 AM
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Ohio
Joined Mar 2000
138 Posts
Re: Re: Facts first

Quote:
Originally posted by Graham Stabler
>Is there a internal voltage booster or does the electronics run on >1,2 V ?

No booster
Graham, Yes booster.

Although the motor and actuator coils run off of the battery voltage minus transistor V drops, the electronics is actually running on 3V, if I remember right.
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Old Nov 27, 2002, 10:49 AM
Sticky Shepherd
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Oxford/England
Joined May 2001
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YOUR RIGHT!!

So my next question is, is the large capacitor (0.6g) part of the RF circuit or the dc-dc converter circuit. If we are running from a lithium polymer we might not need it. Having said that without it running it from the lipoly might blow it up.

Now as for crippling caps, good news for cheapos like me, my car came in a snow globe type box and isn't a real bitcharger and doesn't have cripple caps on either rx or TX. I also just tried driving the tx at 4.2v. The output to the antenna went from 128mV to 208mV according to my scope, should help range a fair bit. I'll also just add a longer antenna at both ends.

Graham
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Old Nov 27, 2002, 11:07 AM
Sticky Shepherd
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Oxford/England
Joined May 2001
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A bit further

I took the large capacitor off and the receiver continues to function but only when the input voltage is over 3v. The capacitor is obviously the smoothing for the DC-DC converter as I can see switching noise on the 3v rail when the input is below 3v. Once above three volts the noise disapears as the dc-dc shuts down. I guess that if I remove components to disable the dc-dc then the reciever will work with input voltages in the range of a liPoly cell and with a 0.6g weight reduction. I may find that the loss of the capacitance causes noise problems but there are many surface mount caps that are much smaller and should do the trick.

The story will continue.

Graham
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Old Nov 27, 2002, 11:15 AM
Thats NOT indestructible
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Graham

What cap are you talkin bout in your most recent post ?

For ne one who is interested, the LXX Char G's are fully compatable with the real thing's parts, and are made as well, just not payin for tommy

Josh
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Old Nov 27, 2002, 11:43 AM
Sticky Shepherd
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Oxford/England
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the big meaty one on the back of the rx, it isn't the cripple cap but a smoothing one for the dc-dc

Just taken the dc-dc chip off and the rx still seems to function from about 2v to 4.2v, more testing

Graham
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Old Nov 27, 2002, 11:48 AM
Thats NOT indestructible
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Cool Graham

Do you think that all the rx's are similar

Could a sm cap replace that one (lighter etc)

Could you buy the smaller caps (if you do use them) and the required transistors and sell them on your site?as rs has a min order of like 10

Thanks

Josh
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