Start Gate: Laser or Micro-Switch?

[Stephen's Dad]

What do most race organizers prefer?

Micro switch or Laser Start Gate?

After fighting the alignment of the Micro Wizard Fast-Track Laser start gate for a half hour I am fed up with it. Never mind the sloppy cabinet close magnets & their tendancy to move around, I am also concerned that the nose height of a car could alter the true start time of a heat.

My biggest concern is a relibale & problem free starting environment. Is there more to consider?

Thanks in advance.

Steve

[Panzer]

If your goal is to have a highly accurate, consistent and trouble free as possible track timing system, I don't think you can beat a micro switch and a well designed spring assisted starting gate controlled by a good mechanical latching system.
My earlier post shows a good example http://derbytalk.com/viewtopic.php?p=10 ... 657b#10166

On the other hand go with the laser if your life isn't already complicated enough.

[gpraceman]

I'd have to agree with Panzer. Please see my post at http://derbytalk.com/viewtopic.php?p=13 ... ght=#13536 on our recent experience.

[Stephen's Dad]

Nice work Panzer. When I outfit our wood Piantedosi I will reference those pictures.

It was Randy's post that got me thinking about the laser gate. Sure enough I had alignment issues immediately.

Since the micro switch is missing from our Fast-Track I have to ask; Is it a normally open or closed switch?

[gpraceman]

Since the micro switch is missing from our Fast-Track I have to ask; Is it a normally open or closed switch?

Normally Open. The switch Micro Wizard sent can be either NO or NC, depending on which terminal you wire to.

[Stephen's Dad]

gpraceman said:

Normally Open. The switch Micro Wizard sent can be either NO or NC, depending on which terminal you wire to.

Which terminal??? There is only 1 terminal.

The laser starter has a single point of attachment on the finish gate located just below the power adapter port. This timer (GP3) is not equipped with the telephone jack. Rather it is more like the small earphone style pin jack. But there is only 1 of these.

[gpraceman]

Which terminal??? There is only 1 terminal.

The laser starter has a single point of attachment on the finish gate located just below the power adapter port. This timer (GP3) is not equipped with the telephone jack. Rather it is more like the small earphone style pin jack. But there is only 1 of these.

I meant that there are two terminals on the Micro Wizard start switch plus a ground terminal. If you wire to one, the switch acts as a NO switch, and if you wire to the other then it acts as a NC switch. You still have a second wire connectd to the ground terminal of the switch.

A headphone jack on the timer end is all you need since you only need two wires, one of those being a ground wire.

[Cory]

http://derbytalk.com/viewtopic.php?p=10 ... 657b#10166

Panzer, I think I recognize the floor tiles in those pictures! (...having had at least one kid there for the last 14 school years, including the current one)

As another testimonial for a mechanical switch, that's what I used for my "experiments" back late last century, and I got fairly tight time spreads with a so-so track. I believe my switch contributing very minimally to the noise.

[Stephen's Dad]

It's time for an update.

I was able to pick up a micro-switch this week. Oddly when installed in the NC configuration the timer worked backwards. Switching to the NO configuration worked perfectly.

Now I have noted a new concern. Regardless of switch positioning, I can still influence the recorded times by altering the release rate of the gate. The margin is fairly small, but if the starter isn't careful then the times could be manipulated.

Perhaps a solenoid operated starting gate is in our future too???

Like so many projects, each step begets another.

What other solutions have folks discovered?

[gpraceman]

I was able to pick up a micro-switch this week. Oddly when installed in the NC configuration the timer worked backwards. Switching to the NO configuration worked perfectly.

It all depends on if the switch is released when the gate drops or if the switch is depressed. Usually, the switch is mounted so that it is depressed by the gate and released once the gate opens.

Now I have noted a new concern. Regardless of switch positioning, I can still influence the recorded times by altering the release rate of the gate. The margin is fairly small, but if the starter isn't careful then the times could be manipulated.

How does your gate operate? It should snap open once it is released by the start gate operator. If the start gate operator is doing the work of opening the gate, then you will get a lot of variation in the times. If you can't improve the situation, you should score by points instead.

[Stephen's Dad]

Randy,

You are correct. The way I mounted the switch, it is depressed as the gate is opened to release the cars.

The start gate is a simple hinged piece of wood with dowels sticking out of it. It is actuated by the starter by hand. The quicker the better.

This is our Packs old track which we keep for build workshops, sign-up nights & this year, an Open Class Derby. Normally it will have an old Judge timer on it that simply indicates finisher by place & doesn't report the times.

Our primary track is a 4 year old Piantedosi Wood. It sounds like I'll need to drag it out of storage to insure we have a decent start gate & that the new switch will fire consistently before we decide on a race format.

Are you familiar with the type of start gate provided on a 2002 Piantedosi or were there different types of start gates supplied with these tracks?

[gpraceman]

The start gate is a simple hinged piece of wood with dowels sticking out of it. It is actuated by the starter by hand. The quicker the better.

Are you familiar with the type of start gate provided on a 2002 Piantedosi or were there different types of start gates supplied with these tracks?

That does sound like their old design. You can try to modify it by adding a latch and some rubber bands to pull it open when the latch is released. You could also contact Piantedosi and get their new style start gate. We did this for our pack in San Diego and it worked out well. If forget the cost of just the gate, but it wasn't too expensive.

If you stick with the current design, you should score by points and not by times.

[Packdude]

We attached a spring to our starting gate to make it snap open when released. However, the switch is depressed while the gate is closed. Once the gate is open/released, the gate moves away from the switch and triggers the start of the timer. I would be wary of having the switch contacted at the end of the opening processs ie the gate hits the switch as it opens completely. Adding the spring to the starting gate also required some padding where it hit the track to keep the cars from bouncing as the gate hit the bottom of the track.

[John Shreffler]

Microswitches have a few disadvantages: They take a pounding, they must be mounted with fairly close mechanical tolerances, and they are prone to switch bounce. The bounce (a rapid series of contact break and makes) can contribute to timing unifority if the switch closure resets the timing to zero. Some timing systems return to zero, some are latched with the first change detected.

A far superior switch is the magnetic switch, commonly used in burglar alarm systems to guard doors and windows. It has 2 parts: Part 1 is a common permanent magnet. Part 2 is a sealed nitrogen filled glass tube containing two separated ferro strips. When the two parts get closer than about an inch, the strips click together and complete the circuit. No pounding, no bounce, and like a hand grenade, when it comes to mounting, close is good enough.

[Buckeye]

We use a laser switch. The beam is broken by the tip of the starting pin, not the car. The profile of the car has no impact on the timer since the pin breaks the beam when it drops down. I find this to be more consistent then a microswitch because of the play in the lever on the switch. The nice thing is that this eliminates any mechanical parts in the mechanism of the timer. It starts breaking a beam and finishes breaking a beam.

If you look at the last few months of the old Wirl track last year there were numerous inconsistencies in the times. Most likely these were due to a failing micro switch on the start gate.

With the laser it either works or does not. If you spring load the gate and break the beam with the starting pin, not the car, you should have a very consistent start.