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I have a PCB design for a capacitive moisture sensor using the PCB traces as the plates of the capacitor. The PCB is shoved into the ground and senses the moisture by the effect on the capacitance between two sets of traces. This is nothing new. Others have done it before. But my question is...
I suggest a capacitive detector, like the sensor in a Theremin. It is so sensitive it will detect objects several inches away. But perhaps it will be less sensitive to a floating object without too much capacitance. Basically it is a high-impedance LC oscillator (use a FET) in which the...
The problem is the ceramic output capacitor. Read the section in the datasheet under Application Information / Output Capacitor. They require between 0.3 Ohms and 22 Ohms effective series resistance for stability. They recommend tantalums for this very reason. Ceramics are too "good"...
I would start by looking at the input to the 1117 on a scope to see if the buck regulator is somehow misbehaving. Then check your connections, such as the polarity of the filter caps on the input and the output. What about the length of the wires from the caps to the 1117? Are they...
Resolution is a theoretical limitation on accuracy. But as Klaus pointed out, your accuracy is often more limited by other things, such as the accuracy of your reference voltage, or the presence of noise. In that case the theoretical limitation to accuracy caused by having less resolution is...
An interface circuit serves two purposes. #1. It can shift the level and range to take full advantage of the ADC range. #2. It can provide a low-impedance drive to the ADC.
As for #1, the range of 0.26 to 1.1 takes about 1/3 the range of your ADC input range. This means you will lose between...
If you connect 30V across drain and source, you will get either 0 Amps (if the gate is OFF) or 1000 Amps (if the gate is ON), which will instantly destroy any reasonable MOSFET. But this is not a condition you should ever see in your induction heater. I assume your circuit has a load in series...
@Barry: I resoldered a few parts and connected the input to a low-Z source. The noise went away. I guess my mistake was assuming that the 1 Meg load would be sufficient without an input connected.
@SunnySkyguy: I didn't know ceramics were so piezo sensitive. The question now is can I use my...
While debugging a little noise problem in an amplifier, I noticed that the circuit is acting like a microphone. Vibrations in the PCB are showing up as noise in the final output.
The circuit is all surface mount, 4-layer, using CMOS MCP604 rail-to-rail op-amps with a very well-regulated and...
Your wattage figures appear to be right on. However from a practical point of view, your second circuit would have an output of -24v from the op-amp. But the TL072 is only built for a maximum of +/-18v power supply rails. I suppose with a ground offset toward the positive side of the +/-18v...
I agree with FvM that for overcurrent protection, your existing low-side shunt is sufficient, and a lot simpler than high-side current measurement, like I had to do in a similar project, which was a solenoid test stand.
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