Build sheet ยท DIY timing

Time your track without a decoder box

OpenStint reads the transponders your racers already own straight off the loop with a USB radio. RaceLyx scores the race. The OpenStint build guide puts the parts at about $65.

Open the build guide Download RaceLyx

From the loop to the scoreboard

Five parts, and the last two are free software on the PC you already time with.

  1. 01

    Wire loop

    A loop of wire across the track at the line, the same as any timing loop.

  2. 02

    Balun and coax

    Matches the loop to the radio and carries the signal back to the timing table.

  3. 03

    RTL-SDR

    A USB radio stick, the kind people use to listen to aircraft. It hears the transponders.

  4. 04

    OpenStint

    Free software on the timing PC that turns the radio signal into passes.

  5. 05

    RaceLyx

    Scores the passes into laps, heats, and mains, on the same PC.

Then, from RaceLyx

  • The scoreboard and pit TV
  • OBS overlays
  • Live results on live.racelyx.com
  • LyxSpotter in each driver's ear

The transponders it reads

Different kinds can run in the same race. RC4 transponders are learned once, and RaceLyx shows the learning on its Decoder page as it happens.

AMB RC3, and RC3 clones such as MRT mPTX and Waldo
Nothing to set up. It reads the number on the case.
RCHourglass and Vostok
Nothing to set up.
MyLaps RC4 Hybrid
Learned once: park the car on the loop for about 25 seconds. After that it reads the number on the case.
MyLaps RC4
Learned once: park the car on the loop for about 12 seconds. It gets a number from 1000 up, which you can change in OpenStint to match the case.
OpenStint transponders
Open source tags you can build yourself. Nothing to set up.

More on RC4 in the OpenStint RC4 notes, and the open source tags are on GitHub.

Racing the same night

01

Build the radio side

Follow the OpenStint guide to lay the loop, wire the balun, and plug the RTL-SDR into the timing PC. Then start OpenStint.

02

Pick OpenStint in RaceLyx

In Decoder Setup choose OpenStint SDR. It connects to OpenStint on the same PC without any address to type. If OpenStint is not running, the decoder shows red and says so.

03

Drive a car over the line

Each pass shows a signal reading while you set the radio up. Learn any RC4 transponders from the Decoder page, register your drivers, and start a practice.

Questions

Do my racers need new transponders?

Not if they run AMB or MyLaps RC3 or RC4 transponders, or one of the RC3 clones. The table above shows what each kind needs on the first night.

Do I need a second computer?

No. OpenStint runs on the same Windows PC as RaceLyx, and RaceLyx looks for it there by default.

Can I mix transponder types in one race?

Yes. OpenStint reads them all off the same loop, and RaceLyx scores them the same way.

What does the software cost?

OpenStint is free and open source. RaceLyx is free for events of up to 5 drivers, and the Home Track plan is $50 once for up to 16.

Who do I ask for help?

For the loop, the radio, and OpenStint itself, the OpenStint guide and its thread on RCTech. For anything inside RaceLyx, email [email protected].

Rather not build anything? RaceLyx also works with LapMonitor and SkyRC LapWiz Bluetooth timers, and with I-Lap and EasyLAP decoders. See every decoder

OpenStint is an independent open source project, not part of RaceLyx. Questions about it go to its RCTech thread. AMB, MyLaps, RC3 and RC4 are trademarks of their owners.

Try it at your next race night

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Windows 10 or newer, 64-bit