Abstract: A monitoring system monitoring electrical components of an apparatus for electrodynamic wall-thickness and defect testing includes a transmitter generating brief signals. An electrodynamic converter has a transmitter coil connected to the transmitter for receiving the brief signals and feeding the brief signals into a workpiece to be tested in which the brief signals are reflected. The electrodynamic converter has a receiver coil receiving the reflected signals. An amplifier is connected to the receiver coil for receiving the reflected signals and an evaluation unit is connected to the amplifier for receiving the reflected signals. At least one damping element and a delay line are connected to the transmitter for delaying and damping the brief signals. The delay line is coupled through the electrodynamic converter to the evaluation unit for feeding the delayed and damped signals to the transmitter coil.

Abstract: Salts of oxaalkylenediamines of the formula IH.sub.2 N--(R.sup.1 --O).sub.n --R.sup.2 --NH.sub.2 Iwhere R.sup.1 and R.sup.2 may be identical or different and are each alkylene of 2 to 4 carbon atoms and n is an integer from 1 to 3, and alkanedicarboxylic acids of 4 to 12 carbon atoms, terephthalic acid or isophthalic acid, which contain hydrazine, their preparation, and nylons prepared from them.

Abstract: A process for the preparation of salts of dicarboxylic acids and diamines of the formulaH.sub.2 N-(R.sup.1 -O).sub.n -R.sup.2 -NH.sub.2 Iwhere R.sup.1 and R.sup.2 may be identical or different and are each alkylene of 2 to 4 carbon atoms and n is an integer from 1 to 3, which contain hydrazine in the form of hydrazine hydrate.

Abstract: A continuously tunable function generator comprises a first function generator (10) with a triangle voltage generator including a comparator (24), which controls the commutation of a capacitor (14) from a charging phase to a discharging phase and vice versa in relation to an upper and lower preset amplitude value of the voltage at the capacitor (14). The triangle voltage (50) arising at the capacitor (14) is supplied to a second comparator (32) of another triangle voltage generator. The second comparator (32), commutates a second capacitor (38) of the same capacitance as the first capacitor from the charging phase to the discharging phase and vice versa. A reference voltage corresponding to the mean value of the upper and the lower amplitude value is applied to a second input of the second comparator. The charging currents and the discharging currents are identical, constant, and adjustable for changing the frequency of the triangle voltages.

Abstract: A process for the continuous preparation of an aqueous solution of a salt of an alkanedicarboxylic acid of 6 to 12 carbon atoms and an alkanediamine of 6 to 12 carbon atoms by reacting the particular alkanedicarboxylic acid with the particular alkanediamine in an aqueous solution of the salt to be prepared. The aqueous salt solution is recycled from a first mixing zone via a transport zone and a second mixing zone into the first mixing zone, liquid alkanediamine and an aqueous solution of alkanedicarboxylic acid are introduced between the first and second mixing zones. Less than the equivalent amount of alkanediamine is introduced, the remaining amount of liquid alkanediamine is added after the second mixing zone, and aqueous salt solution is taken off the first mixing zone at the rate at which it is formed. The salt prepared is used for the manufacture of a nylon.