DS-300 Lap Counter/Timer
Jan. 31, 2005

(Click on any image to see in full size)
Lap counter6

The DS300 Lap Counter/Timer System
Here it is. Each two lane unit is sold separately. The "master" unit
for lanes 1 and 2 goes for $199. "Slave" units provide additional lane
displays for lanes 3-4, 5-6, and 7-8. The "slave" units sell for $99.
You're looking at $300 worth of lap counters here.

Lap counter3

Counters out of the box
You can see a difference between the units here. The lane 1-2 master unit has
controls on top. The lane 3-4 slave unit has a plug on top for interfacing to
the master unit.

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View of controls
(click on image for full size)
Controls (from left to right) are:
"go!" - for starting and stopping races
"mode" - for selecting race mode (Time, Laps, Formula 1)
"0000" - for selecting digits when programming
"0-9" - for incrementing digits when programming
"LAPS/TIME" - selects display of lap count, time behind leader depending on mode
"CHRONOS" - selects display of fastest and second fastest lap for each lane

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Counters (backside)
Here, you can see the lane 1-2 master unit has (from left to right) a power jack,
"stop-go" box interface, computer serial interface and sensor interface.

Inside the box

A Peek Inside the Box
Here, you can see the inside of a lane 1-2 master unit.

Inside the box

A Peek Inside the Box
Here, you can see the inside of a lane 3-4 slave unit.

Lap counter

Counter installed with Stop&Go Box
An optional "Stop&Go Box" controls track power during the race.

Lap counter

Counters installed with optical sensors
In this installation, a Good Year light bridge illuminates optical sensors in
the track. Custom circuitry was built to interface the optical sensors to
the DS300 lap counter. Unfortunately, the DS300 does not support direct
interfacing to optical sensors. It appears to be designed for a trip track
or optical sensors with external circuitry.

Optical Interface

PC Board for Optical Sensor Interface
Here is the optical sensors interface board for the DS300 Lap Counter.
The wires on the right hand side go to phototransistors mounted in the track.
Wires on the left go to a 5-pin DIN connector which plugs into the DS300.


Schematic for Optical Sensor Interface
This is the circuit I used to interface optical sensors to the DS300 Lap Counter.
You could get away with less but this design is rock solid.
The DS300 requires positive polarity on the sense signal.
(Click on image for larger view.)

Circuit Board Layout

Layout for Optical Sensor Interface Board
The circuit board design was created with ExpressPCB. Here is the layout file: InterfaceBoardRev1.3a.pcb

The software to view/modify the board can be downloaded for free from: expresspcb
They will build three of the boards for you for $51.

More information on the circuit can be found in the PDF file here:
Optical Interface for AFX lap counter/timer

5-Pin DIN Connector

Pinout for DS300 Input Connector
Signals enter the DS300 through a 5-pin DIN connector. The signals
are shown. The sense signals look for a positive voltage. You can use
a trip-track that shorts the +7.5 volts to the sense signal or, as we did, you
can use a circuit which provides positive sourcing for the signal.

Computer screen

"PC Lap Counter" software connected to counters
There are at least three or four lap counting applications for the PC
which communicate to the DS300 through its serial port:
SlotTrak V8.15+,
WinSlot from Cric Crac,
PC Lap Counter from PcLapCounter.com
RallySlot (Spanish).

Counters in action in F1 mode
(Click play to watch video)
The "Formula 1" mode is like the "Laps" mode except that, instead
of displaying the absolute lap count for each racer, it displays the
lap count for the race leader and the lap difference for the remaining
racers (e.g. "-1", "-2", "-3", etc).
In all modes, it flashes the lap time momentarily when you cross the finish
line. After about a second, it reverts back to the regular display (laps or
total time).

DS-300 Links

Available Software
PC Lap Counter

DS 300 Instructions

Serial Interface Description
DS 200/300 communication protocol (PDF)
ds300.zip Sample C Source code with compiled application (.exe) for communicating with DS300.

DS Light Bridge
LightBridge.jpg DS Infrared Light Bridge Schematic.
I know this schematic is not totally correct. I haven't identified the light sensor used. It will give you an idea of the circuit.

Other links
DS Electronic Racing Products 2006 Catalog (PDF) A lot of stuff!
DS Racing Computer (DE)
Scalextric USA
Track / Accessories - Timing & Scoring Systems
IBB Auto Racing (Spanish) features the DS-400 Super Tower
Slot32 (UK)

gtw 11/24/2008