mv4wd

To make the program start so it responds as a USB serial port you need at least to connect the 5MHz crystal and the two capacitors C4 and C5.

Kalvo

I thought that by programming the PSOC and connecting it to the serial port, I could check that it would work ok.
thank you fot the support

condac

I have managed to make a working copy of the black original amb loop box. The blue is the original box and yellow is the copy. It is a bit less in signal strength but it works. The schematics that I have on my project site from a few years back was wrong and did not work. But now I have made a change so it works. It can have some improvements made probably to get closer to the same signal strength. Will redraw schematics in the week to come and update the schematics in my github project.

Is this something of interest to the RCHourglass project or is the active parts enought?

mroc

Hello, I have try the LM319 version ( with un original AMB Mx transponder ):
on a loop 1m10x0.69 I have a detection to 5m without problem
on the 10mx0.7m loop, the detection is 0.5m I think I have to change the capacitor from 47pf to 12 pf

the 10m loop has an L = 28uH, the 1m10 loop 4.8uH.

All the test i have done are with the wire only on the grass, not a real MX line.

Here are some interesting link:

Loop antena calculator: http://www.dl0hst.de/magnetlooprechner.htm

other but in French: http://alloza.eu/david/WordPress3/?p=24

https://www.vfdb.org/aktuell/wp-content/uploads/2016/07/Article_pa0rdt-Mini-Whip.pdf


thor

mv4wd

I don't know how this input box works (is it a filter/impedance match, active or passive). Does it work with phantom power from the decoder?

mv4wd

Does this work at 3.58 MHz? I think it might be possible to change the timebase of the decoder, but maybe some of the capacitors need to be tuned. Also it's not confirmed that the preamble and packet have the same size/meaning or RC transponders.
Have you been able to capture some packets with the scope?
I think MX and Kart transponders have a higher supply voltage with a ferrite coil to produce stronger fields. Also I'm afraid for such a short range the normal 'antenna' formula might not be of help. The model is more that of a small field inducing current on one of the two wires. The transponder in the middle of the loop causes the lower signal since the two wires voltages cancel each other. Of course capacitors and inductance of the loop control the sensitivity that should be max at carrier frequency.

condac

It is just a impedance match with a filter to remove some frequency. I have updated the schematics now https://github.com/condac/openAST/bl...box_schema.png it is super simple as you can see. It is a crime to sell these for 200$...

condac

When I compared the loop box in real world on our track, the home built had double the signal strength in the timing software. And the view in the scope had higher signal also. So it works great as replacement for original AMB RC3 decoder atleast.

mroc

Hello,
The signal power are the same as i can see ( Amp Tranx 160 / 0951678 ). I will try to use a mixer ad831A to adjust the frequency from 3.58 to 5 Mhz. I think if i use an 1.42 Mhz signal to transpose the frequency.
The only problem will be the preamble ...

The pic transponder work with this https://www.bechronized.com/motocross-mx-supercross-sx-1 system,

But i don't understood how it works, has i have seen, the loop send a busk 125khz signal, and the transponder return a 5 Mhz bask signal, modulated on a 315Mhz carrier (chip are: 5150 cpu and ??? )

Thor

DannyRC2

Hi Guys - at first many greetings from germany and a great respect to all involved in this great project!

The original loopbox is a balun: this smart board converts the unbalanced to balanced signal on 75ohm Cable - with filtering of noise. With it you can use up to 100m signal cable between loop and decoder without any amplyfier.
I rebuild my own loopbox with same signal quality like original one... tested on RC3 RC4 and alternate decoders...
My question is to use this instead the amplifier on the decoder described here - because most tracks have the mylaps loop and box installed here and need only an alternate decoder system....like this interesting project here...

kind regards
Danny

mroc

Hello,

I the schematics public ? Today i check the lm319 amps. without the condensator on the loop, signal from my transponder, with a ferrit antennae with same inductance as the normal is
allmost four time more powerful as the standard AMB TX transponder fully charged.

Thor

mv4wd

Wellcome aboard. It should be tested if the phantom power does not upset the balun and the impedance and signal level match. I'll try to build the balun and see the results. It would be nice to work with both loops if possible

condac

EDIT: i didnt remember that i already posted this...
Here are the schematics for the working loop box i made: https://github.com/condac/openAST/ra...box_schema.png

DannyRC2

I mean there is a missing Resistor in your loop condac... If you measure the original box you will get 100kOhm on RG59 output side and also on loop input side...
thats the missing resistor maybe your box gets than stronger signal.

My self designed box works with 15 nF and 2x 1nF and the original core 6:14 measured with mylaps up to 200 hits in 1m testing loop not under ground, in real race approx 120 - 160 hits

The original core couldnt detect yet but has measured Douside 10.27mm Dinner 5.75mm x High 3.85mm (Da 0.404inch Di 0.226inch H 0.151inch) and no color.
I have tried a T44-2 core but hits 60-100....not acceptable. i must investigate what core its exactly is - any hints????

condac

I removed the 100kOhm on the loop side because when I measure my original there is no resistance at all on the input....