# DC linear solenoid

abs_vicky
I am using a DC push-type solenoid as the mechanism for shooting in my robotics project. I have to use 12V DC supply and have to shoot TT balls for distances upto 3-7 feet. The solenoid specifications suggest that it requires 60 amp current. How do i generate this??
Thanks in advance

## Answers and Replies

Antiphon
A car battery sounds perfect.

Science Advisor
That solenoid sounds very overpowered for shooting a table tennis ball.
I have seen a small plastic gun do better than that.

You could try connecting an 1.5 volt alkaline "D" cell across the solenoid contacts, and see how far you can fire the table tennis ball with the solenoid.
Then try two in series if that isn't enough.

At full power, it is possible that the solenoid would punch a hole in the ball rather than shoot it.

It actually works better to have the ball touching the solenoid plunger as it accelerates rather than hit it after it is traveling at full speed.

Bob S
For a TT ball, perhaps using a capacitor for storing electrical energy for pulsed discharge into the solenoid, and maybe a pneumatic piston for pushing air behind the TT ball. A piston the same diameter as the TT ball would be easy to implement.

Bob S

BilPrestonEsq
The car battery might be the most simple. Maybe a car battery with a push switch going to the coil and then a resistor and back to the battery again. 8 D cells (1.5v*8=12v) would not supply enough power. I just built a little coil gun the other day with a camera flash circuit(pretty common) and then another one with some capacitors in parallel I got out of a stereo hooked up to a couple of 9v batteries in series. And about the car battery, you might want to look into how to do that safely and not just take my word for it. Simply shorting the battery can cause it to explode acid all over you so some sort of a resistor would be necessary. I don't know how much knowledge you have on the subject so just a warning incase. Let me know what you come up with.

abs_vicky
Actualy, the problem is that i have space limitations. The solenoid would be fixed on my robot(fully automated), so there is no scope of a car battery as everything has to be on-board

Science Advisor
Got the PM.

You need to do some checks with that solenoid to see what it needs to get enough power.
It doesn't seem suitable if it has to have 60 amps. That is a huge amount of current.

As I suggested, try it with a single alkaline cell. This will give less power than the solenoid is capable of, but maybe enough to fire a table tennis ball.

abs_vicky
Got the PM.

You need to do some checks with that solenoid to see what it needs to get enough power.
It doesn't seem suitable if it has to have 60 amps. That is a huge amount of current.

As I suggested, try it with a single alkaline cell. This will give less power than the solenoid is capable of, but maybe enough to fire a table tennis ball.

Sir can you please tell me the design of such a solenoid?? I mean the various parameters like
1 Gauge of wire used
2 Number of turns
3 Stroke length
I have to operate the solenoid at 12 volts

BilPrestonEsq
Do you have to use the solenoid that you currently have or can you design a new one?

abs_vicky
No I have to design a new solenoid . I only need to know the specifications. Plz help me out !

BilPrestonEsq
Oh well in that case, 8 aa batteries in series will give you 12 volts. I say aa instead of d cells because of the limits on size and weight you vaguely described. Can you use capacitors?

BilPrestonEsq
The power of your ttball launcher is going to depend on 1.the turn density in your solenoid. Just the number of times you wrap the magnet wire around whatever it is your wrapping it around in a given length. So you are going to need very thin wire to get more turns in the given length. And 2. the current you are passing through the wire. 3. the permeability of the core( the tube your wrapping the wire around). Well all those factors are going to contribute to a stronger magnetic field inside your solenoid not including the rest of your design.

BilPrestonEsq
you know you should just check out some DIY coil gun websites to get some ideas. Not sure if I am saying stuff you already know either.

BilPrestonEsq
https://www.physicsforums.com/attachments/https://www.physicsforums.com/attachments/31186 are you thinking something like this?

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abs_vicky
Your drawing is just perfect. This is roughly the diagram of my solenoid.

Bob S
The solenoid will need an iron yoke around it to concentrate the magnetic field and maximize the force. You might look at designs of AC solenoids on the web. To achieve 60 amps with 12 volts, the total coil wire resistance has to be less than 0.2 ohms. Do you know what stroke you need, and the required launch velocity?

Bob S

abs_vicky
desired launch velocity is around 10m/s