start tree circuit I have been working on

Drag racing style light trees
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Doug-in-the-woods
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start tree circuit I have been working on

Post by Doug-in-the-woods »

this circuit has not been built as of yet but it is a cluimination of 3 different circuits so it will probally work. Parts are on there way here from Mouser Electronics.
the start tree circuit (the one with a 4017 counter is just a count to 5 and halt (green light) closing the switch will activate the tree = blue light comes on. closing switch causes the 555 timer to pulse at 1 secondintervals
the 2804 circuit is the output to drive small current draw lamps (up to 500ma)_my plan is to use 4 mini xmas lights wired in parelle==current draw-need to measure but shouldn't be to much.
the pinetree circuit is just a finish line circuit (first over the line cub car race timer) but instead of photo transistors I have replaced w/ 2n3904 transistors.
in theroy this should work 3 yellow lights, one green. the finish line circuit controls the red light so onlythe first one will light red.
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SuperDave

Re: start tree circuit I have been working on

Post by SuperDave »

In my experience you need to start with a complete 'real' schematic and not ignore things like current. A great easy-to-use and FREE schematic and PC layout program can be had here http://www.expresspcb.com/ExpressPCBHtm/Download.htm The gotcha on the PC layout is you have to buy boards from them but within the industry they're cheap, fast and good. At least with a complete schematic you should eliminate some of the gotcha's that can creep in when combining separate pieces.

Somewhere around here I have a photocell order of finish detector I designed in 1981 that even allows for ties within a prescribed time. (Designed, not easily adjustable after the fact.) If I can dig it out I'll post it. As you may have noticed in other posts, I don't recommend photo cell detectors, nor for that matter order of finish detectors, unless you're building them in 1981, pre-computers and before better sensors.
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Re: start tree circuit I have been working on

Post by Doug-in-the-woods »

My plan is to breadboard each circuit, then soder to a prototype board after each is working. Should make finding problems easier.
I tried using PC123 but do not have the time to learn a new program.
Will give expressPC a try.
I need to dig up some old mini lights to measure current but 500ma or less per output of the 4017 shouldn't be a problem (I hope??)
Using IR emitter/ detectors instead of photo cells.
On the LM339 circuit the phototransistors are replaced with 2N3904 transistors controled by the output from the 4017.
The circuit (all three connected together) should work.
"famous last words" LOL
SuperDave

Re: start tree circuit I have been working on

Post by SuperDave »

Assuming you're talking about a 74HC4017 (or any similar family member) its output current is spec'd at +/- 25mA max. They will drive an LED (with an appropriate resistor) but not anything approaching 500mA without a power driver in between.

Since 2N3904's are not photo sensitive what is it that detects the car's passing?
Doug-in-the-woods
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Re: start tree circuit I have been working on

Post by Doug-in-the-woods »

the 4017 drives the UNL2804 which are 8 darlington arrays which will handle 500ma
the 2N3904 replaces the phototransistor in the "who got a red light first" circuit-what elese to call it?
a second circuit which has the phototransistors in the circuit detects the cars for a lane win indicator.
The circuit looked just as good for both so am building two identical circuits but one has the phototransuistors while the other has a 2n3904.
I had several SCRs (a very simple circuit) but felt using the LM339 is better.
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Re: start tree circuit I have been working on

Post by Doug-in-the-woods »

circuit is coming to life.
I thought I was dead in the water as I had a very small soder trace shorting out the power to the 555 thus the chip actually started to smoke.
I found problem (RS proto boards suck ) fixed it.
had a copper trace come loose, fixed that. Using only a 15watt iron.
maybe after I get circuit up and running (building it in stages as the entire circuit is 3 seperate circuits with a little added, I will make an actual printed board.
Starting gates are coming along as well.
Will post some pics
just need to locate some colored xmas bulbs for start tree.
After all is working then you folks here can build one for added excitement to your pinewood derby.
could be fun.
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Re: start tree circuit I have been working on

Post by Doug-in-the-woods »

circuit is alive and operating. Finish up building the tree itself today as well as the solenoid/ start gate mechanisim.
The tree is going to utilize 12v automotive clearance lights for the 3 yellow lights, a Radio Shack 12v Blue light for prestaging light, a RS 12v green and red lights for GO or DQed indicators.
the red light circuit uses relays as none of the finish line circuits I found on web have circuit "latching"
will Email pics and circuit if anybody wants more info.
can't wait to actually try it all out.
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Re: start tree circuit I have been working on

Post by Stan Pope »

Doug-in-the-woods wrote:the red light circuit uses relays as none of the finish line circuits I found on web have circuit "latching"
Not sure what the concern is here ... but RS flip-flop (made from a couple of NOR gates) "latch", one input (R) "resets" and the other input (S) "sets". What am I missing?
Stan
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Doug-in-the-woods
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Re: start tree circuit I have been working on

Post by Doug-in-the-woods »

I got frustrated so I went with relays.
easier to control 12v dc lights.
had several minior headachs - circuit worked one night, next morn, wound'nt work?
found and repaired problems etc. - thats electronics
didn't have any NOR gates, just a exclusive OR gate.
Probally could have built but am / was getting frustrated.
Been proto-typing for last 2 weeks when I get time.
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Re: start tree circuit I have been working on

Post by Doug-in-the-woods »

this project is coming alive.
still hung up on the start tree electronics. Fried couple transistors and maybe an IC?
Stan Pope is consultiting on circuit.
built and operating the solenoid mechanisim for both lanes.
Even added an adjustable release so both solenoids release the start gate exactly the same (plunger length sticking out of solenoid before solenoid is activated.
measured w/ calipers length of solenoid body w/ plunger sticking out--within .001 inches.
of coarse the release leavers are exactly the same as well as length of arm from hindge to release leaver.
Will try to get pics tomorrow.
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Re: new revised output

Post by Doug-in-the-woods »

this project is driving me nuts as the circuit is built in sections then each section is working (debuged) then on to the next section.
working on output section, wanted to use mosfets but couldn't get to work.
Wire length/ wire flux, switch bounce all play havock w/ electronics.
going w/ relays to address the outside world.
Ordered relays from Mouser (local RS all out of DPDT relays)
the circuit is actually working, lights flashing, the tree looks good.
only 30 days until the big race.
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Re: start tree circuit I have been working on

Post by Doug-in-the-woods »

heres the schamactic of actual circuit.

playing w/ designing a circuit board to clean up board as they have lots of cut and taped wire etc.

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If someone wants to build then have at it.

will put together a parts list and photos of tree and solenoid mechanisim (works really well but need to mount to track etc.)
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Re: oups! need reset switches etc.

Post by Doug-in-the-woods »

still need to add reset switches etc.
It could be very easy to add a reaction timer to circuit. start timer moment the yellow light goes out and green light comes on.
Also adding another voltage regulator for relays (the lights tend to use lots of current as present regulator gets hot, needs a heat sink.
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Re: start tree circuit redrawen

Post by Doug-in-the-woods »

I found several mistakes in the first and second circuits.
this one is hopfully without mistakes.
Planning on etching a board to clean up my mess--wires going every where etc.

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