Derby Talk

Hello all!

It looks like there are several of you all working on a project. That is great! The project I was working on with the fellow from Picprojects was rolled into the one he already had and is now available as a kit. You will have to add your own lights and solenoid. Pic Projects.Org

I am going to use MR16 bulbs for the lights - Besthongkong The lights will be mounted on a tree made from PVC pipe.

And the solenoid I picked up at a local surplus place. Or... I may just trigger the track manually.

2nd Generation will be built with an Arduino. I have a kit that I just purchased from Adafruit Industries. If you are a electronics geek, you will love her kits.

Good luck to everyone and your builds, and have a great race season!

Whipping up something quick and easy for someone who got in touch with me...wondering something. I have a schematic in front of me for the Racemaster IV timer (don't ask me where I got it, I can't seem to find it again, even a day later) and am wondering how best to snag a light tree pulse from here. I'm thinking of breaking out the serial connection between the computer and the light tree to simply drive a AtTiny to control some relays.

GPRM says it can only output pin 4 or pin 7, but on the Racemaster schematic, it shows pin 4 used by a lane sensor, and pin 7 being a second connection to ground. Is this second connection necessary? I should be able to interrupt that pin (tie it to ground at the timer side and use pin 7 from the computer) to drive the light tree / solenoid, shouldn't I? Electronics skill is fairly high, I just don't know anything about the commercially available equipment like the Racemaster 4. If only there was a third pin option for light trees.

Another functionality question, is that signal in GPRM a one time thing? Or will it repeat a certain number of times? (ie use it for clocking)

Cheers,
Alton

By the way, I think I'm going to be releasing schematics and kits just after this derby season draws to a close (got to get my own track ready to go first! )

The RaceMaster IV is wired a bit weird. I think they were trying to setup the board to use a DB9F or a DB9M connector (mirror image wired) but didn't quite succeed. I have had customers with both of these connectors, but the majority are DB9F. It seems that Pins 1 and 5 are jumpered but Pins 2 and 4 are not. Those with the DB9M connectors have problems with communicating to the computer until Pins 2 and 4 are jumpered. It was good sleuth work from one of my recent customers that discovered that.

GPRM can trigger a tree with Pin 4 or 7, depending on how the tree is wired. So, if you are building the tree, it is your choice of which to use. The trigger signal is +12V and will remain on for the amount of time that you specify in the Hardware Options screen. There is no pulsing of the signal, just on or off.

I would not recommend trying to tap into the timer's serial port connector for your tree. Instead, you can make a Y connector (a small project box, two DB9M's and one DB9F) where you wire one output connector for the timer (Pins 2, 3 and 5) and the other output connector for the tree (Pin 4 or 7 and Pin 5).

Sorry, I guess I wasn't totally clear. It is my intention to create a bit of a break-out box for this. Thanks for the tips.Looking at this schematic, I think pin 4 is taken by a lane? The schematic is at http://home.simplyweb.net/bosworth/timers&.htm , about 3/4 of the way down the page. The trigger signal is 12V, even over the serial connection? It's looking like the Racemaster operates at 5V (at least the one I'm looking at), and I don't see any voltage regulators. It would be helpful if anyone has any photos of the inside of one of these things (want to make sure this schematic is accurate-ish).


Never mind. Realized I was only looking at a partial schematic. Sigh. So I'm good to use 4 or 7 without interfering with the operation of the timer?

Thanks,
Alton

OK, we're talking about two totally different timers. I thought you were talking about the commercial timer from JIT, Inc.

That DB9 you see is merely to connect the timer unit to the sensors. It is not a serial port interface at all. Those plans do not have a computer interface.

Oh. See, I have never in all my days seen one of these commercial timers. So when I searched for Racemaster IV pinouts, and this popped up, that's what I went with. On the actual real Racemaster Timer product, are pins 4 and 7 used for anything, or am I able to purpose them for my own needs? Sorry for the gratuitous amounts of confusion.

Serial timers use only Pins 2, 3 an 5. However, the RaceMaster IV (commercial timer) seems to be wired a bit weird, as I was originally trying to explain. Maybe it is to use a bootloader to load in the firmware via the serial port or to use either DB9 connector. Regardless, I would really suggest the Y connector. Then if you are triggering the tree, you know that you will not be causing the timer any problems, since the timer is only exposed to Pins 2, 3 and 7.