reciever side schematics

[chungerz]

I seen a transmitter schematics available on line for the bit char-g. Is there one available for the reciever side (car)? I found several reference design for the various chipset that is used in these cars. But they all deviate from the reference design.

I am trying to mod the transmitter/reciever pair inorder to run up to 12 vehicles at the same time. (please save the FCC talk, I know all about it. The transmitter will be broadcasting with very low power, I am only looking for a range of 5-6 feet)

If anyone has done this, or have the schematics available, please post or e-mail me at chsiehhu@ucla.edu. I am an EE student, these cars are going to be a part a of larger project.

thanks in adavnce, sorry for the long post.

I'm not sure if this would help, but you should be able to run 10 bits with no problem. The standard bits and clones have 27, 35, 40, 45, 49 and 57mhz while the super bit char-g's use 3 frequencies varied at 27mhz and 3 frequencies varied at 49mhz.

The variable resistor on the pcb of the car (the component with the coils) has a tiny screw that you can adjust which controls the frequency of the car. Trying to alter the frequency of the car can only be done by replacing or modifying this variable resistor.

Would you by chance know how to unsolder a component like that off of a bit PCB? The variable resistor has four solder points, so I would have to remove the solder somehow. An EE colleague at work mentioned a small spring loaded vacuum (shaped like a pen) that sucks up the solder when activated. Do you know any standard method like that to remove solder? I'm just an ME, not a sparky

[chungerz]

those are variable inductor coils. I know about the LC tank that makes up the reciever filter. How ever doing the math, it doesn't add up to the center frequency of 27.145mhz of the car that I have. That is why I am looking for a schematic, I am sure there is another component of the filter that I need to adjust as well..

as for removing the solder, the solder sucking pen (I actually don't know the "real" name for it) works very well. I use it many times very useful.

But if you don't have one handy, you can use soldering iron and melt the solder and remove a little bit at a time (I MEAN A LITTLE BIT) do that if you are really bored or desperate to remove the solder.

[nasphere]

did you all know copper brade (solder wick) works a heck of a lot better for the small stuff, it kinda absorbs it all somehow, but you have to use a higher heat on the soldering iron, standard heat wont let it work right.

i use that wick stuff alot!! it cleans the connections up real nice. it is kinda expensive though, like $2 for a really small roll (5'), so i only use it for the small stuff, the larger stuff i use the solder sucker... it works really good, but only for the bigger stuff, it doesnt seem to clean up the connections as well as the wick on these little cars.

BE EXTREMELY CAREFULL you might accidentally desolder a resistor and find yourself trying to solder it on for over an hour!!! or you might accidentally suck up a resistor you just heated if your using a sucker...

i did this stuff a while ago to relocate the "huge" parts on the pcb to fit it in the body.