It is common for people to ask, "How can the TASER device generate 50,000 volts from 12 volts at the battery of cells (for the ADVANCED TASER M26)?" The answer is that TASER devices use a series of transformers and capacitors, together with the principles of physics (P = I * V or power equals current times votage).

There's a well-known stunt performed by acrobats using a "see-saw" device as a lever. Two acrobats jump from a given height (say 10 feet) onto one side of the lever. On the other side, a single acrobat is launched twice as high into the air. The lever transfers the momentum of the two acrobats into one acrobat, sending him twice as high.

Understanding Transformers

One can think of a transformer as an electrical lever. As electrons enter one side of the transformer from a certain voltage (similar to the height of the acrobats' jump), the leverage ratio of the transformer transfers this energy to electrons on the output side of the transformer. Depending on the design of the transformer, it can either step-up the output voltage, or step it down. In either case, the transformer is constrained by the power input (P = I * V).

In its simplest form, the transformer "trades" volts for amperes, or vice versa. In the example above, if 2 amperes of current at 10 volts are delivered into this transformer, 1 ampere of current at 20 volts will be the output. (Note that in the real world, transformers are not 100% efficient, so the actual output will be slightly less than the input.)

The battery of power cells is the power supply in any TASER device. In this illustrative example, the battery of cells function like a water faucet, supplying the power to the circuit. The "pressure" out of the battery of cells in the M26 is roughly 10 volts (it drops from 12 volts as the battery of cells is loaded), the current is roughly 4 amperes, hence the total power from the batteries is roughly 40 watts.

An Illustrative Representation of the TASER® M26 Circuit

The electric current from the battery of cells is directed into a transformer (Transformer 1) that steps up the voltage by a factor of roughly 200, from 10 to 2,000 volts. As the transformer steps-up the voltage by 200x, it also steps-down the current by 200x, from 4 amperes input to roughly 0.02 amperes (the actual output is less, about 0.013 amperes due to inefficiencies).

The output of Transformer 1 is connected to a capacitor. A capacitor is a device that stores electric energy, just like a bucket would store a flow of water. Similar to a bucket, a capacitor can only hold so much energy. Once the capacitor is full, it dumps its energy into Transformer 2. Transformer 2 steps the voltage up again, from 2,000 volts to a peak of 50,000 volts. Similarly, the current drops again to an even lower output current.

One important note - the 50,000 volts is a peak potential voltage, or open circuit voltage; it is not what is actually delivered to the person on the receiving end. If we return to the water analogy, the wires from the TASER device to the target are like hoses that carry the current. If you place a section of plastic wrap over the end of a garden hose, the pressure will build up inside the hose. At some point, the plastic wrap will finally burst, and the water will flow out the end. When the plastic bursts and the water starts to flow out, the pressure inside the hose drops, and the pressure of the water flowing out is actually lower than the peak pressure that developed within the hose itself.

In a TASER system, the wires do not always make contact with the skin of the target. If there is an air gap between the darts and the body of the subject, the air gap will function as a barrier, just like the plastic wrap on the hose. The voltage (pressure) will build up inside the TASER wires until it can break through the barrier (the maximum would be 50,000 volts, which can break through a barrier of approximately 2 inches of air gap). Once the barrier is breached, the voltage (pressure) drops immediately as the current flows through. In the case of the M26 TASER, the maximum voltage delivered across the body of the target is about 5,000 volts, with only 1.3 volts average (one-second baseline). In the case of the TASER X26, the maximum voltage delivered across the body of the target is about 1,200 volts, with only 0.76 volts average (one-second baseline).

The big picture from this illustrative look at the TASER device is to understand that at each level, as the voltage is increased, the output current is decreased.

Figure 17 is a graph depicting the current output of a single AIR TASER 34000 pulse compared to a TASER M26 pulse. The vertical axis is the magnitude of electric current. The horizontal axis is time, measured in microseconds (1 microsecond = 0.000001 seconds).

Time (sec)

Figure 17 Comparison of Current Output of AIR TASER 34000 and TASER M26

Note that for a very brief period of time (about one microsecond), the peak current output from the AIR TASER 34000 reaches about 8 amperes (remember that a strong static shock can reach a peak of 30-37.5 amperes). However, the duration of the primary phase of the impulse is extremely short - roughly five microseconds. This is about 1/200,000^th of one second. To give you an idea of how short this pulse duration is: if you stacked 200,000 sheets of standard copier paper, the stack would be roughly 50 feet tall. If this stack of paper represented just one second in time, the duration of the primary phase of the AIR TASER 34000 pulse would be the width of just one piece of paper!

Because the pulse duration is so extremely short, the amount of charge actually delivered is quite small. Consider if you turn on a faucet, even at a very high flow rate, but you turned it back off after 0.000005 seconds. Even though the flow rate for that moment in time might be high, a very small amount of water would actually have time to flow out - probably just a drop.

If we look at the chart again, since the vertical axis is the flow rate and the horizontal axis is time, we can calculate the amount of actual charge delivered by taking the area under the curve.

In the case of the AIR TASER 34000, the charge in the primary pulse is roughly 0.00003 coulombs (or 30 microcoulombs). The charge in the entire pulse (including both the positive and negative phases) is roughly 70 microcoulombs. However, it is the charge in the first phase that appears to be the most important for causing peripheral nerve stimulation. Once the current changes polarity, it is actually shifting charge in the opposite direction. Hence, if the nerve cell has not reached its action potential threshold during the first phase, the second negative phase actually works against it. Therefore, we believe it is the charge in the primary phase that is most relevant. However, in the interest of conservatism for rating purposes, we will consider the entire charge delivered. Since the device pulses roughly 15 times per second, we know that it will deliver 70 microcoulombs (total rectified charge) * 15 pulses per second = 1,050 microcoulombs per second. Since current is the flow rate of charge, 1,050 microcoulombs per second = 1,050 microamperes = 1.05 milliamperes.

Since the pulse intensity from the AIR TASER 34000 was found to be insufficient to cause any motor neuron mediated stimulation of muscle, a new pulse waveform was developed for the TASER M26. Note that the M26 delivers a pulse that is both taller and wider than the AIR TASER 34000. Accordingly, the total charge delivered from the M26 pulse is also higher, roughly 86 microcoulombs in the primary phase and 182 microcoulombs total rectified charge delivered in the entire pulse waveform. At a nominal pulse rate of 20 pulses per second, this equates to an average rectified current of 3,600 microamperes = 3.6 milliamperes (0.0036 A).

Due to all the equipment law enforcement officers must carry, it was reportedly difficult for officers to fit the ADVANCED TASER M26 on their duty belts for full-time carry. Accordingly, the company set out to develop a smaller TASER device that could still cause a similar amount of incapacitation. The result was a more complex waveform using "Shaped Pulse™" Technology. (For more details on Shaped Pulse Technology, see TASER Training CD/DVD version 10+.) A new waveform developed using Shaped Pulse Technology, which delivered a comparable amount of charge to the waveform from the TASER M26, was implemented in a new device called the TASER X26, introduced in May of 2003.

Figure 18 Comparison of Current Output of ADVANCED TASER M26 and TASER X26

Note that the TASER X26 uses a lower peak current than the ADVANCED TASER M26, but a longer pulse duration. As a result, the X26 delivers a roughly comparable amount of charge in each pulse. In laboratory experiments, the output of the TASER X26 was designed to cause 5% stronger muscle contractions than the M26. The X26 delivers roughly 110 microcoulombs per pulse, at a pulse rate of 19 pulses per second, for an average rectified current of 2,100 microamperes or 2.1 milliamperes (or 0.0021 A). (Note, the primary phase of the X26 is actually negative in polarity compared to the main pulse - however most of the charge delivered is of the same polarity, one of the reasons that the X26 waveform is more efficient.)

These patented pulses have proven highly effective at incapacitating even the most aggressive subjects while minimizing the risk of serious adverse effects. Due to the extremely short pulse durations used in TASER pulses, the charge per pulse and average current are miniscule when compared to continuous outputs such as AC currents from a wall outlet, industrial equipment, or power lines.