基本上我们都知道，当我们用电流通过线圈时，它产生磁场开始吸引铁磁材料，就我而言，我制造了一个电磁铁。

问题是，如果我们保持线圈通电，它会继续吸引电枢。所以会发生的是，电枢朝向线圈加速，一旦电枢的磁中心到达线圈的磁中心，线圈上电枢的力就变为零。但是当电枢有动量时，它通过中心，此时线圈通过磁场开始将其拉回并使电枢减速，或者将其加速回中心。你在视频中看到，这会导致电枢摆动，好像它附着在弹簧上，并最终停在中心位置。（电磁减震器）因此，确保电枢达到最大速度的最佳方法是在线圈到达线圈的磁中心时立即关闭线圈。如果线圈和电枢都是对称的，它们的磁中心将与它们的物理几何中心相同。有两种方法可以做到这一点：一种方法是完美地计算线圈的关闭时刻，或者另一种简单的方法是使用传感器并检测电枢何时到达最佳位置以关闭线圈。在某些设计中，他们只使用电容器并将其线圈放电，电容器电能快速耗尽。这样线圈就没有电流将电枢拉回来，这有点像线圈定时。在我看来，所有时序设计的问题在于，不容易轻易预测线圈达到最佳效率所需的时间（因此你会需要模拟器

在上面的电路中，我添加了D1，我忘了在视频中显示。没有这个二极管导致我爆炸，我没有在视频上捕捉！（叫你用单向开关，叫你用晶体管 续流这种东西只是为了照顾单向开关的需要而强行降低电弹效率，老老实实的用机械开关可好）

这个电路只是我想到的一种快速的演示方式。这绝不是最好的方法。特别是因为我的红外传感器具有有限的响应时间（3kHz）。

我从Digikey购买了这些零件，这里是他们的零件编号供您参考（您可以选择自己的）：

OP1：欧姆龙的EE-SX1070Q1：International Rectifier的IRF7739L2TR1PBFQ2：通用2N3904 NPN晶体管或类似物D1：通用肖特基二极管，能够> 30V，> 10ASW：通用按钮，常开R和C：通用L1：手部受伤

这是电路描述：

Q1晶体管基本上是开关L1电感的开关。当Q1关闭时，L1将尝试通过沿相同方向继续电流来释放存储在其中的能量。如果没有D1，这将导致Q1的漏极电压跳跃到一个巨大的数字，打破Q1并使其短路。这将使Q1的电源短路，并导致Q1爆炸并损坏线圈。具有D1，当D1的Q1导通时接通电流回路并保护Q1。另一个副作用是扭转L1的磁极性，这有助于加速电枢。

当开关SW闭合时，它通过1uF电容向Q1的栅极发送高电平电压，使其导通。 1M欧姆电阻有助于放电1uF电容。

OP1必须偏置，使得当传感器未被阻挡时，晶体管输出处于低于0.4V的低电压以确保Q2关闭，并且当电枢进入传感器阻挡红外光时，光耦晶体管输出跳跃到上方0.7V使Q2晶体管导通。

所以基本上当按下开关SW时，Q1的栅极电压跳跃，将其打开。这会将电枢吸入线圈，一旦电枢到达传感器，Q2就会开启，将Q1的栅极拉低并将其关闭。

它的效果和你在视频中看到的一样好。但是这个设计存在一些问题。如果内部没有电枢并按下触发器，则Q1的栅极电压会随着栅极电容器被1M欧姆电阻放电而下降。在某些时候，这会导致Q1漏极 - 源极电阻的增加，这意味着Q1上的高功率下降会使其上升。所以总应该有一颗电枢。我们无法移除1M欧姆电阻，因为没有它，栅极电压可能永远不会恢复到0伏。

就像我说的那样，这个电路仅用于演示，更好更快的电路可以更可靠地工作。但功能概念保持不变。

现在更多的线圈可以串联在一起，每个人都有自己的快速传感器。电枢可以更小，重量更轻，以帮助加快速度。也可以有不同的方式来打开和关闭串联线圈。例如：

- 一旦第一个线圈关闭，第二个线圈打开等等，它们可以一次打开和关闭一个。

- 他们可以一次打开两个。例如，如果我们有从L1到L4的4个线圈，则L1和L2可以一起打开。当电枢到达L1和L2之间时，L1关闭并且L3打开，这样可以有更好的加速度，但功率使用更多。

- 所有线圈可以一起打开，但在电枢通过时一次关闭一个。

而经验法则是：绕组的数量越多，线圈上的功率越大（电压和电流）（垃圾王：扯淡啊 电感量和esr大了线圈的实际功率和有效功率只会降低），电枢的加速度就越大。当然，在完美的位置关闭线圈也是非常重要的。

我希望你喜欢你所读的内容。如果没有，请发表评论，我会尽可能地写一些更新。谢谢，保持安全！

从这篇文章中我们可以看得出来唐马儒根本没看懂线圈X的工作原理，也是被外网的民科一忽悠就觉得人云亦云的认定自己做的电磁铁是真家伙了 然而，真正的电磁弹射器的原理是电磁感应，可不是什么线圈吸钢铁钉 记住这一点

Posted on January 24, 2013

Did you always wish you had a gun? Well just make one for yourself!

Somewhere in the video I mentioned it was a “Rail Gun”, but it is actually a coil gun. They both work with magnetic force, but differently.

Here I describe the detail design of the coil gun, so you may turn away if you hate details:

Basically as we all know, when we turn on or energize a coil, it starts attracting ferromagnetic material, in my case a steal bullet I made.

The issue is that if we keep the coil on, it keeps attracting the bullet. So what happens is that the bullet accelerates towards the coil and as soon as the magnetic center of the bullet reaches the magnetic center of the coil, the force of the coil over the bullet becomes zero. But as the bullet has momentum, it passes the center, at which point the coil starts pulling it back and decelerating the bullet, or accelerate it back towards the center.

You see in the video that this results in the bullet oscillating as if it was attached to a spring, and eventually stops at the center.

So the best way to make sure the bullet reaches maximum speed is to turn the coil off as soon as it reaches the magnetic center of the coil. If the coil and bullet are both symmetrical, their magnetic center will be the same as their physical center.

There are two ways to do it: one is to perfectly time the turn-off moment of the coil, or another easy way is to use a sensor and detect when the bullet reaches a sweet spot to turn the coil off.

In some designs they just use capacitors and discharge them in a coil and the capacitor runs out of charge quick. This way the coil won’t have time to pull the bullet back, which is sort of like timing the coil.

The problem with all the timing designs in my opinion is that it is not possible to easily predict the required time to keep the coil on, as it depends on the bullet mass, coil field, original distance of the bullet from the coil and etc… and therefore the coil either turns off too early or too late, both resulting in a slower bullet.

So I believe to make the on time of the coil independent to all these factors, the best way is to have a sensor and detect the location of the bullet and turn it off on time.

In my design, to turn the coil off I placed an infrared (also known as optical) sensor to detect the tip of the bullet right where their centers meet, and this would turn the coil off using a simple circuit.There are other options for the sensor such as Hall Effect sensors, which can be much faster. You need a fast response time as any delay in response will cause the bullet to pass the center and result in some deceleration. Especially when you have many coils rather than one, the speed of the bullet in the final stages is super fast.

The following circuit is what I designed and made.

Circuit Schematic of the Coil Gun

In the circuit above I have added D1, which I forgot to show within the video. Not having this diode caused me grief and explosions which I didn’t capture on video!

This circuit is just a quick way of doing it for demonstration that came to my mind. It is by no means the best way to do it. Especially since the infrared sensor I have has limited response time (3kHz).

I purchased the parts from Digikey and here’s their part numbers for your reference (you may choose your own):

OP1: EE-SX1070 from OmronQ1: IRF7739L2TR1PBF from International RectifierQ2: Generic 2N3904 NPN Transistor or similarD1: Generic Schottky Diode Capable of >30V, >10ASW: Generic push button, normally openR and C: GenericL1: Hand wound

Here’s the circuit description:

Q1 transistor is basically the switch that turns the L1 inductor on and off. When Q1 turns off, L1 will try to release the energy stored in it by continuing the current in the same direction. Without D1 this would cause the voltage at the drain of Q1 to jump to a huge number breaking Q1 and shorting it. This will short the supply through Q1 and will result in exploding Q1 and damaging the coil. Having D1, when Q1 turns of D1 turns on closing the loop of the current and protecting Q1. Another side effect is reversing the magnetic polarity of L1 that could help accelerating the bullet.

When the switch SW closes, it sends a high level voltage through the 1uF capacitor to the gate of Q1 turning it on. The 1M ohm resistor will help discharging the 1uF capacitor.

OP1 must be biased such that when the sensor is not blocked, the transistor output is at a low voltage below 0.4V to make sure Q2 is off, and when the bullet comes into the sensor blocking the infrared light, the optocoupler transistor output jumps above 0.7V turning the Q2 transistor on.

So Basically when the switch SW is pressed, the gate voltage of Q1 jumps, turning it on. This will attract the bullet into the coil and as soon as the bullet reaches the sensor, Q2 turns on pulling the gate of Q1 low and turning it off.

And it works as good as you saw in the video. There are some issues with this design though. If there is no bullet inside and the trigger is pressed, the gate voltage of Q1 drops as the capacitor at the gate is discharges by the 1M Ohm resistor. At some point this results in increment of the Q1 drain-source resistance, meaning a high power drop across Q1 that will blow it up. So there should always be a bullet. We can’t remove the 1M Ohm resistor because without it the gate voltage may never return to 0 volt.

Like I said, this circuit is only for demonstration and a better and faster circuit could work much more reliably. But the functional concept remains the same.

Now more coils can be put together in series, everyone with its own fast sensor. The bullet can be smaller and more light weight to help accelerating faster. Also there can be different ways to turn the series coils on and off. For example:

– They can turn on and off one at a time, as soon as the first coil turns off, the second one turns on and so forth.

– They can turn on two at a time. For example if we have 4 coils from L1 to L4, L1 and L2 can turn on together. As soon as the bullet reaches between L1 and L2, L1 turns off and L3 turns on, This way there can be better acceleration, but more power usage.

– All coils can turn on together, but turn off one at a time as the bullet passes them.

And the rule of thumb is: the more number of winding and more power over coil (voltage and current) the greater acceleration of the bullet. Also of course turning the coil off at the perfect spot is very important too.

I hope you like what you read. If not, please drop a comment and I will write some update when I can. Thanks and stay safe!