hi, I found some failry cheap pressure transducers on ebay, the only problem is that I have no idea if I can use them with arduino

Type PA-21R/80853.3-120
Range - 0...120 bar.
Output- 4...20mA
Supply-8...28VDC.

Why the output is given in 'mA'.... is this TTL compatible?

if i supply 5V to it and attach the output to one of analog input PINs on arduino will it work ?

you must have connected the wires the wrong way - I know because I did the same thing and it behaves exactly as you described

I have tried many values between 48 and 360, but it does not improve the movement, but I still would like to know

that wouldn't improve anything... that value just tells the programme how many steps are needed for each revolution (useful for some commands)

by these solenoids he means solenoids used in commercial airguns... a solenoid strikes a hammer valve and that releases air which propels ammo through the barrel

ohh well you might as well google it
http://www.network54.com/Forum/275684/thread/1203760289/Solenoid+trigger+-+working

not to sound like a dick but this forum is not the best place to discuss solenoid hammer valves... if you've got questions like 'is this code ok' then I guess there are ppl who can help you
...but if you're talking about specific application then you should find an airgun forum to get all the info you need

I am going to be a d### and say it again... it would be nice if there was one official code and ( and  driver example something based on L298 would probably be ok for most users)) for a CNC controller that can work with mach3 or EMC 

yeah I know I know I can make one myslef... probably I could but if there are ppl better than me at this stuff then... 

thx...
I think I know why it is that difficult to understand 

SLRS008C − SEPTEMBER 1986 − REVISED NOVEMBER 2004

It would be better if they had written a new data sheet rather than revised (poorly) the old one

I just want to be sure I understand the difference between the two.

L293D has inbuilt protection diodes, while L293NE does not, am I right ?
(yeah I know the latter is rated a bit higher, I am asking only about clamping diodes)


Ohh what about L293DNE ? is it like a newer version of the two ?
one that has both the higher output of L293NE and inbuilt clamping diodes of L293D ??

I've read the datasheet but I am still a bit lost.

( datasheet here>> http://standby-shop.eu/photo/_pdf/L293.pdf?sess_id=a5dc5d224a1a44887ff009d9ed1b9a0c )

If you need a balistic caluculator to hit something that's just 10 meters away then you're overcomplicating stuff :-D

The OP didn't say how fast or how far but if you consider air resistance, there's only numerical solutions. My student borrowed my book smiley

Yeah, then you need to solve differential equations numerically

Calculating that isn't all about calculating. The real problem is to know the exact cd value of your projectiles (mass and other stuff is easy to determine). Also if they're not stable in flight then you're pretty much you know what ;-)

The projectile is the most important part of your system. The gun just has to be relatively consistent (meaning it has to achieve more less the same muzzle velocity), but that's not something that can't be achieved.

If your system (the gun + projectile) isn't up to the job then it doesn't matter what equations you use or how good the code is.... since it will be no use anyway


Do you plan to use an off the shelf airgun or do you want to build one yourself ?

+If the former then you might as well use charigun (that's a free ballistic calculator for airguns - google it) and use to create a look up table (I guess that's what this thing is called)
+If the latter then you've got to make sure that the whole platform (gun + projectile) is accurate. Once that's done you can actually start looking for equations, approximations of the cd value for given shapes etc.

uhmmm this equation does not take into consideration air friction, right ?
which means it might be completely useless if you actually want to launch something

believe it or not but air friction has significant influence on stuff... especially if your projectiles are low density

I hope you're aware that a 2 position valve stays in one of the two positions ?

So you can't stop it in between, you'd need a 3 position valve to do that

Bit of an exaggeration that. However, if you are as stupid as you sound then maybe you do.

lol being a dick doesn't make your dick get any longer   

No offence but there are things at which I am acctually pretty good and forums where I am a kind of advanced member...
though I don't think it gives me right to act like a dick - just because I know more than others and they ask questions that have already been answered 100 times doesn't mean I am in anyway better than them

I don't know how it works here

Though yeah, let say that I get your idea

I don't agree with the above statement... sure there is a lot of work to be done, but if you can provide a simple to use standardised library, code and a simple tutorial on building a step motor driver (yeah I know you can find quite a lot of information on the internet)...

Getting everything to work well together seems like the biggest problem for most ppl...


What's the point of developing more than 30 or 60 independent projects if one would serve the community better ?

I don't think there is any point in reinventing the wheel each time.... That's what arduino is all about - you don't have to spend hundreds of hours just to read the value of one sensor and send them to processing. Sure all of us could throw away their arduino boards and design a micro controller of their own... lol but is it the point

EDIT
ohh yeah sorry mike I must have missed that... I think I've seen your thread about it but it wasn't as informative as that link...

anyway thx for contributing

lol FAIL
uhmm sorry, but I've seen way too many threads suggesting 'get a Darlington driver and use it to power a 5V relay,  that in turn powers an AC relay, and so on etc. so somehow I missed that 

Anyway... I am not very experienced so I'd like to know if there are any disadvantages of SSRs (apart from price and overheating) ?

I might not be very experienced, but I think there is a much better approach - get a Solid State Relay

There are lots of relays that can switch insanely high currents, but there are also lots in 110/240V at 1-4A range

I hate when ppl mention that hexapod robot... roughly 50% of search results for 'hexapod + CNC' redirects to a video or an article about it

BTW I am pretty surprised that there isn't (that I know of) one 'official' tutorial (with library + wiring, what programs to use etc.) of the most basic XYZ CNC setup

I expect the response 'why don't you make one yourself?!?', lol but I am not yet there so... 

i think it's great... not the most impressive project that I've seen but it is great