Make a 0-25 mA current limiter. I want to take a control voltage of 0-5 V as input and have it control a current of 0-25 mA through a restive load (the restive load may vary between 0-200, it`s represented as R2 below). The O2 op-amp is used to make a differential amplifier with a gain of 2. Example: 25mA of current through the lo
Click here to download the full size of the above Circuit.
ad R2, op-amp O2`s output should be 5V (marked CSense). The output from op-amp O2 is then the input to op-amp O1. Op-amp O1 compares the control voltage with O2`s feedback to limit the current. Or at least that`s my intention. I have triple checked my pin-out and wiring, and messed around with lots of other things, but the circuit still just oscillates. When V2 is a higher value the oscillation is slower. What I am seeing on the DSO is that mosfet T1 goes between full on and full off, and CSense is a triangle wave that varies in amplitude with the control voltage. A higher control voltage makes CSense have higher amplitude and lower frequency. The oscillation frequency varies from about 50kHz to 150kHz. Update Everyone is focusing on O1, but I think the problem is in the O2 circuit. Below is a DSO screen shot. V2 is at 1. 25 VDC. The yellow trace is the voltage over R2 @ 100. The red trace is the output of O2 (marked as CSense in my schematics). I would expect the red trace to be 2x the yellow trace, but instead it`s a completely different shape! What in the world is going on For clarity: I would expect the yellow line to be 0. 625 VDC, and the red line to be 1. 25 VDC (same as the V2 input). Also my power supply is ~8 VDC here, things blow up at 24. The V2 input is a sine wave. The output is supposed to follow the input. If you change V2 to DC, the output will also simulate as DC. On my bench, V2 is DC, but the output...
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: