DE1573826C - Bridge circuit with strain gauges - Google Patents

Description

3 4

Zero values caused by temperature fluctuations are in the order of magnitude of a few 100 Ω and point fluctuations in the bridge circuit can be used to define a specific bridge through a corresponding temperature input resistance and source resistance. For the dependent resistance, for example a nickel invention, they are not essential. Further resistance, in one of the transistors fitted 5 resistors Äs and Ri serve as emitter-resisting bridge branches to be balanced. Likewise is the status of the transistors. In one of the branches equipped with transistors, temperature-dependent sensitivities are possible, a combination of a resistor, for example a nickel resistor, temperature-dependent resistor, for example io Rn, is connected in series with the emitter changes through a temperature-dependent resistor Rs or Re a temperature-dependent bridge circuit lying parallel to the feed diagonal resistor. The resistor Ä15 serves to compensate that of a nickel resistor with a constant current ratio in the two transistorized resistors. To make the relationship of the bridge branches insensitive to temperature fluctuations branch currents and thus also the zero point of the gene. The base electrode bridge circuit can be readjusted by a potentiometer, the transistors Ti and Γ2 are each readjusted, which connects the two with transistors 15 stator or Ri with the measuring diagonal points of the provided bridge branches and connects the bridge circuit. As a result, the tapping thereof represents one of the supply diagonal points of the transistors due to voltage changes on the bridge circuit. The zero point of the measuring diagonal is controlled in such a way that the bridge circuit ratio can also be set on a potentiometer for the branch currents through the resistance measuring strips, which always remains constant parallel to the measuring diagonal 20 Ri and Rz. The measuring voltage is switched and at its tap the supply diagonal of the bridge circuit is loaded by a double diagonal point between the Dehmmgsmeß- potentiometer R * and Rio . Connected to the stripping-equipped bridge arms, this potentiometer can be any one. Partial voltage of the measurement diagonal voltage decreased

The measuring diagonal of the bridge circuit can be 25 men. A double potentiometer is located parallel to the measuring diagonal. The series connection of two resistors Rn and both taps of this potentiometer allow Ru with a potentiometer Ria. The tap of the es, any partial voltages of the measuring voltage potentiometer Ru is to be tapped with the strain gauge, side feed point of the bridge circuit is connected.

To adjust the bridge input resistance 30 den. The zero point of the bridge shell can be

and the source resistance of the bridge circuit can be set. The other feeding point of the

The emitter-collector paths of the Tran bridge circuit can be made by tapping one of the

Resistors bridging resistors provided both transistorized branches of the bridge circuit

will. The measuring effect naturally decreases with the connecting potentiometers Ru

something off. 35 shown. With the tap of the potentiometer Rn

The invention is based on an embodiment, the current ratio and thus also the example, which is shown in a figure, can be set closer to the bridge zero point. The bridge explained. Two variable resistors Ri and R2 are fed with an impressed current from the generator through the resistor elements of Dehor G. The nungsmeßstreif en is formed parallel to the food diagonal. They are in two series connection of the resistors Ria and Ä17. An adjacent branch of a bridge circuit has resistors, in the exemplary embodiment, the resistor, in the other two branches of which the status jRie, represents a temperature-dependent resistor-collector path of two transistors Ti status, for example a nickel resistor. And Γ2 are located. The emitter-collector paths of the The parallel connection is used to compensate for transistors are bridged by resistors i? 7 and Rs 45 caused by temperature fluctuations. The resistance values of these resistors contested the sensitivity of the bridge circuit.

1 sheet of drawings

Claims (7)

I 573 826 1 '· ■■ -' ■ 2 strips and the two remaining claims: equip bridge branches with inactive resistors. This bridge circuit naturally delivers 1. Bridge circuit with strain gauges, only a smaller measuring effect. in the case of the "Wissenschaft und Technik", 18th year, bridge branches each one mechanically opposite. No. ^r: 4, 'April 1952, pages 105 to 116, a Deh circuit which is claimed in relation to the other is known, in which there is a common feed diagonal point marked with one another by a voltage measuring strip, characterized by the fact that in two subsequent branches of a bridge circuit one bridge branch each has a transistor (Ti, Ts) is arranged with mechanically opposite to the other beanseiner emitter-collector path,. ', called strain gauges is arranged.
and the base electrodes of the transistors via From German patent specification 958 160, class resistors (Rs, Ri) each with adjacent 42i 7/01, a temperature sensor circuit is known which is designed as a bridge circuit and is connected to the diagonal points of the bridge circuit, at which the measuring voltage at which the collector-emitter path of a single one is taken. . Transistor in one to the feed diagonal of the 2. Bridge circuit according to claim 1, there is a bridge circuit parallel bridge branch. The characterized in that in one of the base electrode of this transistor is an AnTransistors (T ₁ , T ₂ ) equipped bridge branches, 20 final point of the measurement diagonals of the bridge series with the emitter-collector path of the device. With the help of this circuit is a transistor , a temperature-dependent resistance amplification of the bridge current changes is achieved (Ris) . so that they can be read by a measuring instrument in 3. Bridge circuit according to claim 1 or 2, the bridge diagonals can be displayed,
characterized in that parallel to the supply 25 In utility model 1781195, class 42i 7/01, diagonals of the bridge circuit a series is a temperature measuring device with semiconductor sensor circuitry from temperature-dependent resistance wrote. A push-pull circuit of (Ria) and a constant resistor (Rn) two transistors to amplify the diagonally is connected. voltage of a measuring bridge applied. Only one 4. Bridge circuit according to claim 1 or 3 ° of the transistors is in a branch of the measuring one the following, characterized, bridge. that the transistor-side feed diagonal point of the opposite should be done with the help of the Bridge circuit the tapping of a potentiome- invention does not change the bridge current or ters (Rn) is. the measurement diagonal voltage can be increased. You lay 5. Bridge circuit according to claim 1 or 35 rather the object, with the help of one of the following, characterized in that the transistors supplied by a power source that the measuring diagonal of the bridge circuit an impressed feed current in a ratio of 1: 1 to potentiometer (Ru) is connected in parallel , and this ratio is to be kept constant regardless of the overall tapping of the current on the strain gauge side and the resistance of the strain gauges located in the bridge-supply diagonal point of the bridge circuit. The task at hand is given by a bridge 6. Bridge circuit according to claim 1 or circuit with strain gauges, in which in two of the following, characterized in that by a feed diagonal point of the bridge schaldaß on the measuring diagonal of the bridge circuit interconnected 'bridge branches each for the tap of the measuring voltage a double 45 a mechanically opposite on the other hand beanpotentiometer (Rs, Ru) is provided. strain gauges according to the 7. Bridge circuit according to claim 1 or the invention in that connecting one of the following, characterized in that the bridge branches each have a transistor with its that the emitter-collector paths of the tran-emitter-collector path is arranged and the transistors by resistors (2? 7, Ra) to the fixed 50 base electrodes of the transistors via resistors laying of bridge input resistance and in each case with adjacent measuring diagonal points the source resistance are bridged. Bridge circuit are connected to which also ". - the measuring voltage has been removed. ■ The voltage on the measuring diagonal of the bridge ■ ■ ■ '■ · ■' ■■ ■ '■■' - '■ 55 circuit ist'dadurch at a detuning of the Bridge as big as a bridge circuit with active strain gauges in each of the four It is known, for example, for electrical bridge branches. Measurement of forces on a by the forces it is often desired, for example, from space occupied Spiral springs in the areas of 60 are based only with two active strain gauges Spring that can get by with an expansion or a compression. In addition, when attaching the are subject to each two strain gauges to strain gauges on a spring body large arrange and apply a total of four strain gauges carefully, otherwise through the to be connected in a bridge arrangement, so that the appearance of "creeping" is undesirable next door the measuring diagonals with changes in the stretching effects can occur. For this reason too The highest possible electrical conditions are desirable for a circuit with a possible measuring effect accrues. It is also known that such strain gauges can get along with such little strain gauges Bridge circuits only with two strain gauges, but nothing to lose in terms of the measuring effect.