Instruments For Testing Your Innovations

AC magnetic field is generated when an alternating current is passing through a coil. The AC current is a time-

An AC current driver such as the TS200 and the TS250 can output many amperes of current through an AC magnetic coil to produce the electromagnetic field. The TS20/TS250 can drive coils such an AC Helmholtz coil pair directly. This called the direct-

Figure 2. TS250-

Figure 1. The TS250 driver amplifies current and drives a magnetic coil to produce AC magnetic field.

Model |
Voltage Range |
Peak Reactive Current (Note 1) |
Peak Resistive Current (Note 2) |

TS200- |
- |
0 – 4.0A |
0 – 5.0A |

TS200- |
- |
0 – 2.8A |
0 – 3.8A |

TS200- |
0V to + 15V |
0 – 3.5A |
0 – 4.5A |

TS250- |
- |
0 – 5.0A |
0 – 6.0A |

TS250- |
- |
0 – 3.1A |
0 – 4.4A |

TS250- |
- |
0 – 2.1A |
0 – 3.0A |

TS250- |
- |
0 – 1.7A |
0 – 2.5A |

TS250- |
- |
0 – 4.0A |
0 – 5.0A |

TS250- |
- |
0 – 2.1A |
0 – 3.0A |

TS250- |
- |
0 – 1.7A |
0 – 2.5A |

TS250- |
- |
0 – 2.1A |
0 – 2.5A |

The TS200 and the TS250 are high-

Note 1. Magnetic coil is inductive which means its power is reactive. The TS250/TS200 output current is reduced for reactive power.

Note 2. Maximum resistive current is obtained at max voltage minus 1.0V. For example 9.0V for the TS250-

Figure 4. Connect two TS250 in parallel to increase the output current by 2x.

Magnetic coils are highly inductive. Their impedance is reactive which means the real part of the impedance is nearly zero (very low resistance) as discussed in Equation-

The TS250-

A simple method to increase an electromagnetic driver output current (and stronger AC magnetic field) is to make the coil more resistive. To do that just add a resistor in series with the coil as shown in Figure 3. Use a resistor with resistance between 0.5Z to Z, where Z is equal to the high-

Figure 3. Impedance matching will increase the AC electromagnetic field driver output current.

Equation-

Equation-

Strong Magnetic Field Using a New Resonant

Series Resonant for High-

Equation-

AC electromagnet (magnetic coil) impedance is given in Equation-

Z=R + jωL

Equation-

Equation-

At low frequency the magnetic coil impedance (Equation-

At high frequency on the other hand, the AC electromagnetic coil impedance is increased proportional to the frequency, ω. The magnetic coil impedance is often very large. Generally, the reactance dominates the overall impedance. For example, an 1mH high-

50mm diameter 100kHz Helmholtz coil set

207mm diameter (109mm inner) 20mT Helmholtz coil pair

175mm diameter 80mT 10kHz Helmholtz coil set

30mT 10kHz Helmholtz coil pair with high-