Question

(b) A 5-kn rotary pot-meter is connected to a 0-350 robotic arm. The pot-meter is supplied with 15-V. The output of this pot-meter is connected to an interface circuit. The input resistance of interface circuit is 40 ko. Find the loading error at the output of the pot-meter when the robotic arm is set to 70° (8 Marks) (c) The output of unbalanced wheatstone bridge is amplified 300 times using a differential amplifier. In the circuit R 1000 & x 0.003. The amplifier has CMMR 75. Find values of the output voltage V, and compute errors in percentage. (9 Marks) 10V Question No.3 (CLO-1) (a) In the industry, the profit per unit of a product is calculated by subtracting unit cost of the item from its price. List the factors involved in cost per unit. Then discuss how automation affects these factors. (12 Marks) (b) Write a detailed note on toothed tachometer? Ensure to include structure/construction, principal / working and usage. (12 Marks)

solve these two parts please

Answer 1

Toothed rotor variable reluctance tachometer:

This tachometer generator consists of a metallic toothed rotor mounted on the shaft whose speed is to be measured. A magnetic pick-up is placed near the toothed rotor. The magnetic pick-up consists of a housing containing a small permanent magnet with a coil wound around it. When the rotor rotates, the reluctance of the air-gap between the pick-up and the toothed rotor changes, giving rise to an induced emf in the pick-up coil.

This output is in the form of pulses, with a variety of wave shapes.
Since the number of teeth is known, the speed of rotation can be determined by measuring the frequency of pulses with an electronic counter. Suppose a rotor has T teeth, the speed of rotation is n rps (rotations per second) and number of pulses per second is P.

Hence speed n = pulses per second/ number of teeth = P/T rps = (P/T) x 60 rpm
If a typical rotor has 60 teeth, the number of pulses per second will give the speed in rpm.

Advantages:
1.   Simple and rugged construction
2.   Maintenance free
3.   Easy to calibrate
4.   Easily transmittable information
Toothed Rotor Variable Reluctance Transducer INDUCTOR PULSES TO TIMER/COUNTER/ FREQUENCY METER SHAPED AMPLIFIER SHAPED PULSES ENT TOOTHED -ROTOR FIG 1 9AEI 306.26 72

Magndic Pick-up Elsctronie Counter Matching Trensformer Touthed Rotor Toothed Rotor Tachometer

A toothed rotor variable reluctance tachometer is described here. This tachometer generator consists of a metallic toothed rotor mounted on the shaft whose speed is to be measured. A magnetic pickup is placed near the toothed rotor. The magnetic pickup consists of a housing containing a small permanent magnet with a coil wound round it. When the rotor rotates, the reluctant e of the air-gap between pickup and the toothed rotor changes giving rise to an indicted e.m.f. in the pickup coil. This output is in the form of pulses, with a variety of wave shapes. The frequency of the pulses of induced voltage will depend upon the number of teeth of the rotor and its speed of rotation. Since the number of teeth is known, the speed of rotation can be determined by measuring the frequency of pulses with an electronic counter. Suppose the rotor has "T'teeth, the speed of rotation is "n"rps and number of pulses per second is "P". A typical rotor has 60 teeth. Thus if the counter counts the pulse in one second, the counter will directly display the speed in rpm. It is mentioned above that the pulses have a variety of wave shapes. This is immaterial, as this tachometer is always connected to an electronic counter, whose requirement is merely that the ampltude be great enough to trigger a count Uses Variable reluctance tachometer probably is the most common type of tachometer in use today

Advantages:
1. Simple and rugged in construction.
2. Maintenance free.
3. Calibration is easy.
4. The information from this device can be easily transmitted.