The data logger consists of a simple op-amp amplifier circuit that amplifies the signal and sends it to be digitized by a PIC16F688 microcontroller, serialized, and sent to the computer`s serial port via a MAX232 serial driver: I guess you are already wondering about some of the unusual arrangmenents in the analog part in the schematic diagram abo
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ve. Part of it is because of the voltage differences between the analog and digital part: the op-amps work on 12V while the microcontroller and the serial driver require 5V. Part of it is to make the different kind of sensors I plan to use easier to connect. Finally, this is partly because I`m really lazy and when I got the things to work to my satisfaction I refused to change anything. The point is - unusual or not, it works. IN1 is a DC-input with a range of 1-11V. Whatever voltage is applied to IN1 is directly passed to the amplifier. Try to keep the voltage centered around the 6V point for best results. IN2 is an AC (self-centering) input with a range of ±5V. The trimmer potentiometer R1 connected to this input centers the signal at 6V when the sensor signal is not changing. Switching between inputs is done by shorting the JP1 jumper. You can either use a switch there and do this manually, or wire JP1 into the connectors you use to plug-in your sensors (which is the way I did it). Before finishing with the input part, notice the optional amplifier OP2 in the lower part of the diagram. Some sensors based on a voltage divider work best when the voltage is split close to the half point - in other words, if you have a resistor/photoresistor bridge and in the particular conditions the photoresistor has 10k resistance, the signal will be stronger if the other resistor in the bridge is also around 10k. Use the trimmer...
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....
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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....
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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....
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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.....
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