Need Circuit Board Design Help

[BTAutoMag]

i would normaly ask my uncle about stuff like this. im great with wiring circuit boards together and have taken on seriously complex projects but... ive never designed a board. as i said i usualy ask my uncle (i.e. tell him what the board needs to do and he emails me a schematic in a couple days time and i assymble) but he is moving to alabama and has no time to help me out.

What i need:

A) i need to send a .25 second pulse to a solinoid with a 24 volt rating and i need the .25 second pulse to be delayed for .5 seconds

B) in the time before it sends the pulse i need the board to move a small object 1 cm and after the pulse retract it

C) after it retracts i need it to make a motor turn a 8"x19" cylynder 1/6th of a turn

i need this to happen with the push of one button

so with each dash below as .25 second...

I I I I I
BBBBBBAAAABBBCCCC




i know your curiosity is running wild so heres what im making... a 6 barrel potato launcher... (to be used with paintball grenades in senario games) me and my best friend have built it and it works great but its kind of a hassle because all the stuff being controlled above we have to do manualy... which means we have to rotate a 6 barrel drum 1/6th of a turn then seal it with duct tape(will be sealed differently when we get the electronics) then make sure not to shock ourselves when we connect the wires hanging there to a 24 volt source

[robertjuric]

Ok see if I got this right:

you want to: move an object 1cm, wait .5 seconds, send .25 second pulse to a solenoid, retract object, make another motor turn?

Ok what I would do is use a stepper motor to move the object, then use a 555 timer in monostable mode(delay mode) for the .5 second delay, then another 555 timer in monostable multivibrator mode(yes there is a difference, this is like a timer, it will close a circuit for however long) for the .25 sec pulse. then use either a bjt or a mosfet that acts as a switch to reverse the polarity of the stepper motor to make it go backwards, then after it goes back, you can use another bjt or similiar device to make another stepper motor rotate.

Thats just a broad suggestion, but it should work. Depending on how much force the stepper motors have to push, they arent the strongest motors in the world. You can email me or try to catch me on AIM if you need more help, its in my sig. Id be glad to help.

[robertjuric]

Ok Im bored and thought Id go into a little more detail.

What you need is a trigger, then when you press that trigger it activates the stepper motor, then you have to figure out how to tell when the stepper motor has stopped moving, this could be done w/ a simple logic transistor that sees if there is any power going to the stepper motor.

Then that transistor triggers the 1st 555 timer, this timer is the delay timer. http://www.andy-clarkson.me.uk/555/delay.html has some good info on 555 delay timers. Once that delay is done, the output will go high, which would activate the 2nd 555 timer, this 555 timer is the one that sends your pulse to the solenoid. Its sometimes called a one shot timer, http://www.andy-clarkson.me.uk/555/mono.html for an example.

Now you would have to figure out a way to shorten the output of the 1st 555 timer, b/c if you didnt, the 2nd 555 timer would just get one continous trigger signal, and it would never stop. So you would have to figure out how to shorten that to less than the output length of the 2nd timer.

Then you have to find out when the solenoid is done firing, Im not sure how you could do this, you might could use another timer set to however long it takes for the solenoid to move so when the solenoid gets its pulse, it starts a delay timer that wouldnt get done until the solenoid is done moving. Then you would use that trigger to switch the polarity of the 1st stepper motor to retract the object. Then again, you have to figure out when the stepper motor is done turning, just like at the beginning, then use that trigger to active your 2nd stepper motor.

Feel free to correct me if Im wrong, but the only thing I see here causing a problem would be cutting the output of the delay timer down short enough so it wont mess up the 1st 555 timer.

Just wondering, why don't you just rework your firing mechanism on your currect launcher, just fix it up so all you have to do is rotate it your self and press the button, or figure something out so everytime you rotate it manually it fires?? Just an idea.

[hitech]

Have you read warpigs article on the basic stamp? You could use that to control everything. Try reading that article and see if you think that will work.

[BTAutoMag]

aight thanks ill try warpig and see if i cant draw something from what you posted

[robertjuric]

Hahaha good luck doing all the timers for that w/ a basic stamp. Plus youd need the one of the higher level basic stamps b/c you'd need the extra memory and I/O lines.

555 timers are simple and cheap.

Keep us posted on how it goes.

[billmi]

A BS1-IC (the cheapest of the stamps) would definitely be up to the task. The advantage of going that route over the 555s is that the timing and sequencing would be done in software, rather than feedback circuits to the 555. For some people, designing complex circuits is no biggie, for me, it's way simpler to break down the tasks and write a program and then use very simple circuits to interface between the stamp and the hardware.

Stepper motors aren't something you just turn on and off (as mentioned above,) you have to run them through their steps, by pulsing the 3 (or 4) coils in the proper sequence - that's something digital control (like the stamp) is really built for. Rather than a stepper motor, and worrying about a drive belt slipping out of sync, and registration problems I'd suggest that the drive logic (steper or straight DC motor) be intexed optically, with a series of 6 tabs which break an IR beam when one of the chambers is lined up with the barrel. Using a stamp, you'd just run the motor until the beam is broken again, and then stop at that point.

If you do undertake the project with a stamp, feel free to e-mail me for advice and help along the way.

See you on the field,
-Bill Mills

[FallNAngel]

OT question: Do you guys have any websites that have tutorials and such for people getting into electronics? I'm alright at programming, but sometimes you just need to make something off a circuit board.. any help would be appreciated. Thanks

[robertjuric]

Hmm well what most sites would have basic electronics theory, Ohm's Law and that kinda stuff. Then it steps up to basic components and their functions like resistor capacitors. Then sometimes it moves up to more complex things like IC's which really only require finding the data sheet to figure out how to wire it to get the desired affect. I think the best way to learn is to find a project, research it, find out what needs to happen, how to make it happen, then make it happen. Sorry its late, so no specific links, but try google.

[Redkey]

I would use pneumatics...

If you had some kind of saw tooth gear hooked up to your barrel assembly it could be ratcheted around using a pneumatic cylinder. This *might* be easier than trying to use a stepper motor. The pneumatics will have more power and would be quicker, smaller and lighter when it comes to moving something that requires a bit of force.

here is a crude drawing... I think

[billmi]

Originally posted by FallNAngel
OT question: Do you guys have any websites that have tutorials and such for people getting into electronics?

See the technical section of WARPIG - on the right bar, there's stuff for airsmiths. There are a series of articles on electronics from soldering technique to basic electronic principles on up to adding control circuits to a Basic Stamp and programming it (software is in the article) to build an LCD gun controller board. I've exchanged e-mails with people who've gone from no electronics knowledge to building a working gun control board through that series of article.

See you on the field,
-Bill Mills

[FallNAngel]

Yes, I've already read both of those articles some time ago, sorry I hadn't mentioned that before. Right now I'm looking for the next step. I know you can't just read it and know it... there's a point where you have to just do it yourself. Until that point, I'd like to read as much about it as possible.

[billmi]

The next step is the third article - it's got the circuits and the software to get the job done.