Parallel to Serial Conversion for Starting Tree and Solenoid

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Alden Faught
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Parallel to Serial Conversion for Starting Tree and Solenoid

Post by Alden Faught »

I just upgraded to GPRMv7 and realized it no longer supports parallel port starting trees and solenoids. I put a lot of time and energy into building our tree and gate three years ago and it has really added realism for the scouts. I had an idea to create a stand alone box with a button that could trigger the tree and gate without the GPRM software. I have limited electronics design experience and can understand the flow of electronic circuits but not the nuts and bolts. Basically, I understand their function but can't always make them work...read programming code but not write it.

Searching on the internet I came across this circuit diagram:

http://home.cogeco.ca/~rpaisley4/LM555VaryPerB.GIF

It looks like it has the potential to create the timing sequence needed for the lights and gate. I would use a DB9 serial connector to connect to the computer and the outputs from this circuit would connect to the DB25 on our tree.

Thoughts?

Does anyone know if the pulse from the serial port is +5V?

What is the pulse sequence from GPRMv7? Does it pulse to start the race, again when the last car crosses the finish line, and again before the start of the next heat... :D
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gpraceman
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Re: Parallel to Serial Conversion for Starting Tree and Sole

Post by gpraceman »

Unfortunately, sometimes to move forward, things have to be left behind. Such was the case supporting parallel port devices.

Bert Drake from DerbyTimer.com had been developing a light tree and solenoid controller board, but he seems to have dropped off the face of the earth.

Randy Underwood, author of the current light tree plans on GrandPrix Race Central, had indicated that he was interested in creating some plans for a serial port light tree and solenoid controller. Though, he wasn't sure when he'd be able to get to it.

Regarding your questions, the serial port has two output pins, pins 4 and 7, with pin 5 for ground. It ranges from a -12V low state to a +12V high state. If you have a serial port timer, it is using pins 2 and 3 (along with pin 5 for ground). The other 4 pins are not useable as outputs.

If you wish to use both a light tree and a solenoid, then the controller for the light tree would need to activate the solenoid when the lights go green. GPRM V7 can send a kick-off signal to either device, but it will not coordinate between the two. If the light tree controls the solenoid, you would only need GPRM to kick-off the light tree sequence.

As for that circuit you found, I'm not sure if it will work or not. I know just enough electronics to be dangerous.
Randy Lisano
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Awana Grand Prix and Pinewood Derby racing - Where a child, an adult and a small block of wood combine for a lot of fun and memories.
Alden Faught
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Re: Parallel to Serial Conversion for Starting Tree and Sole

Post by Alden Faught »

Randy,

Thanks for the reply.

Our tree was built using the old plans requiring 110V lights and it houses the power supply for both the low voltage circuitry for the tree and the 24V used for the solenoid as well. The computer connects to the tree and the tree connects to the solenoid.

I will keep working on this project and post my progress.
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