We had a mounting issue with my sons B44.1. His PT (Mylaps Harry and we tried a Cano Club as well) was mounted on the top deck over the servo and we had very sporadic detection. Moved it to the chassis away from the electrics and all was fine. That was with a 9 foot loop.

Ok, thanks. I guess I will run a bit of trial and error with the scope to see how it works.

Is there any way to increase the gain of the amp if it gets marginal?

Also, the width of the loop is mentioned to be 1 foot. But how will a wider or narrower width affect the reception? Will the thickness of the loop wire be a factor? I have a choice between 0.75 mm2 (AWG 18 = 0.8 mm2) or 1.5 mm2 (AWG 15 = 1.6 mm2). I.e will AWG 15 give better reception? Guess not....

There is no simple way of increasing gain. That would take additional components. It also does nothing for the signal-to-noise ratio, and there is quite a bit of noise coming from the car's motor and ESC.

Making the loop somewhat narrower than one foot will reduce the inductance, which permits a somewhat longer loop to compensate. But it also means that the loop should be placed closer to the cars, and the cars must pass under the loop slower for proper detection. This is worth a try, if possible.

Different wire gauge has only a marginal effect on inductance. I chose 18AWG for strength and easy availability, but 16AWG or 20 AWG should suffice.

To be honest, the loop will be under the cars. There is no way that the club would accept a loop over the track. We run 1/8 scale nitro buggies there and there will be crashes for sure where these cars can come flying that will break either the cars or the loop bridge. So either we can make the loop work on ground level - or the whole decoder project is a no go. But I've seen other mentions of successful adaptions of a ground level loop so I am hopeful. However, if you have any tips on how to maximise our luck with this setup I am grateful. The track is mostly clay. The place where the loop will go however will be gravel with wooden cover. But that can be adopted. We could probably put the loop on clay inside electrical plastic tubing that is used in houses for the internal wiring. Not sure what they are called in the U.S. Here they are called TP tubes. Or without tubes directly buried in clay with a piece of carpet above. Another idea was to have a row of garden concrete tiles and put the loop around that row. That would make the loop open to air and still protected. These are the variants that are spinning in my head here.

You have a reasonable plan. The loop must be away from conductive surfaces and objects, and wet clay is quite conductive. The gravel should help substantially.

http://rc-auto.ru/forum/index.php?sh...0&#entry233683
I've got a working version of a serif, works perfectly!

Our loop is tiewrapped to a rubber mat to keep its basic shape and laid out over the astro turf track surface and slightly under one edge so the cars do not lift the mat as they cross.

We have run successfully in rain and even snow:


http://i23.photobucket.com/albums/b3...psyi9lppg4.jpg

Ok! I see snow but not the loop though ;)
It is good to see the Cano decoder can cope with different conditions though. When the loop is put in its position and all is verified the plan is to never move it. Hoping to get the amp box water proof...

Ok, the loop amp is pretty much done now. I was thinking of "debugging" the amp first to see it is ok, but it seems harder than I thought. For one, the output is the same place where I would feed the circuit with power. And that power source is filtered, so I guess it would also filter out the signal I would try to read? Another problem is the voltage. I guess there is no harm in feeding 5V, but the reference readings and trim pot voltages would be off? So perhaps it is easier to build the decoder and use that as the power source - as intended...

Another question is how to connect the loop wire to the enclosure box and pcb. I guess "anything goes", but there ought to be some better alternatives. I was thinking banana plugs. 4 mm LiPo type male plugs could be used then. I'm sure you have solved this already, but I didn't find any pictures of it.

If you look at the schematic for the Phase Detector Input Amplifier, you will see that J1, the coax to the Loop Amplifier, connects to +5V through R1, a 75 ohm resistor. So for testing the Loop Amplifier, all you have to do is feed it +5V through a 75 ohm resistor.

The connector for the timing loop is pretty much your choice. I used the first and third pins of a servo connector, with the middle pin removed. That way if someone trips over the loop, the connector will pull free without breaking anything.

Darn. Having some issues here. The decoder and loop amp are completed with just the C1 tuning for the increased loop length left to do. But I decided to start the decoder up first.
Led lights and power is 5V via the 12 V input. I've hooked up hyperterminal to check the serial output. But nothing. 115200 baud, 8-N-1, no flow control. Used pin 2 and 5 on the serial connector. No communication messages at all.

I've soldered an IC holder for the PIC, to be sure not to damage it in any way so I guess it should be safe, all other soldering was done with great caution and looks perfectly ok to me. Still, somewhere there is an issue. Any idea on where to start debugging? I would guess the greeting message on the serial port is pretty much isolated from all the rest of the decoding stuff so if the PIC has power it should print that message. All else could be pretty much broken but that message should come either way? What if the PIC got fried in customs by x-ray? Just thinking...

I would wait for Howard but initially, make sure you have done the errata:

The 1uF capacitor on U2 (the 7805 regulator) was mislabeled on the schematic (duplicated “C4” reference designators), and consequentially was not included on the board.

The cap should be soldered directly to U2.

The node label “3D” was misplaced on the schematic at U20A pin 3, causing the connection to be ignored. A jumper must be soldered from U20A pin 3 to U21 pin 4.


Also check you have not switched the tx/rx lines DAMHIK ;-)

The first step is to make sure that the 5V supply is smooth and within tolerance. Next check that the clock input to the microprocessor is at 20MHz and has digital levels. Then look for the RS232 output on power-up with no cable attached.

Yes, I've done the errata. And I've read about the switched tx/rx lines of others and which pins to use. So to be sure (and lazy) I used your image of the completed box as reference so I would not be making the same mistake. If I read your DAMHIK right, it might be the case the error is there in the picture? That would explain everything...

EDIT: After close examination of the circuit and schematic I would conclude your wiring to be correct on the picture, and thus I have some serious debugging to do. Time to start up the scope...

Picture is correctly wired as you deduced. Scope time I am afraid.