The circuit consists of a 5-V regulator, constant-current source Dl, D2, and Ql, and op amp gain stage Ul. Power is provid
Click here to download the full size of the above Circuit.
ed by a 9-V battery whose output is regulated to +5 Vdc by the 3-terminal regulator. The emitter of Ql is always 0.6 V below the +5-V line. Resistor R1 sets the current through both diodes Dl and D2 to 5 mA. The resulting 0.6 Vdc across one of the multiturn trimmer potentiometers (R2 and R3), as selected by switch section S2A, sets the current through Ql and the resistor-under-test. When R2 is selected, the test current is 1 mA; when R3 is selected, the test current is 10 mA. On the lower two ranges, 1 and 10, the voltage across resistance-under-test is applied directly to the DMM terminals. On the upper two ranges, op amp gain stage Ul is switched into the circuit and the DMM measures the voltage between op amp output pin 6 and the test resistor. When switch S2 is in position 3 (x 100) the current set by the constant-current source is 1 mA; the multiplying factor is 100. When S2 is in position 4, 1000, the current is 10 mA and the multiplying factor is 100 10 = 1000. Multiturn trimmer-potentiometer R6 adjusts the offset of the op amp so that, with no voltage across the resistor-under-test (i.e., with the measurement terminals short-circuited), the output is zero.
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
characters left: