The trigger circuit (2) includes a transistor (Q2) and a shunt resistor (R1).

In order to measure the current in a shunt, the voltage drop in the resistor of said shunt is evaluated as a measurement of the current.

Measuring circuitry (15) is incorporated between the shunt resistor (1) and terminal members (5, 6).

A variable resistance element that can be incorporated in a reproduction magnetic head is supplied as a shunt resistor of a tunnel magnetic resistance effect element.

A shunt resistor is provided in each branch, which reduces the input resistance of the terminal and thereby reduces the rise and fall times of the input terminal.

A shunt resistor (R5) is coupled between the gates of the parallel transistors (M1, M2) to eliminate odd mode oscillations.

One end of the shunt resistor (R1) is connected with an input end (4) and the collector of the transistor (Q1).

The current limiting circuit also includes a shunt resistor for shunting leakage currents away from the patient.

The other end of the shunt resistor (R1) is connected with the base of the transistor (Q1) and the collector of the transistor (Q2).

The shunt resistor may also be sized to reduce, minimize, or eliminate signal reflections back up the channel.

An inverter (11) is coupled to an EL lamp (14) by a high pass filter including a series capacitor (15) and a shunt resistor (16).