HI LOW DETECTOR SMD INSTRUCTIONS

Table of contents

1. Introduction
2. Schematic
3. Component List
4. PCB
5. Going Further

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SCHEMATIC

INTRODUCTION

What is the Hi Low Detector SMD Trainer?

The Hi Low Detector SMD Trainer is a dual op-amp circuit that compares an input voltage to two different voltage levels; one representing too high and one representing too low. The two potentiometers represent the different high and low voltage levels, and the two on-board LEDs light up when either level is detected. The output of the Hi Low Detector is inverted, meaning that the Hi output switches low when the input is too high, and the low output switches low when the input is too low.

What can you do with the Hi Low Detector SMD Trainer?

Besides the obvious use of SMD training, the Hi Low Detector can be used in applications where a signal needs to be maintained at some level. For example, a greenhouse can use a temperature sensor to open windows if it gets too hot, but what about if it gets too cold? With the Hi Low Detector, the low output could be used to control a heater, thereby giving a greenhouse complete control over its temperature.

Another fantastic use of the Hi Low Detector is as a water tower controller. If the water level in a tank becomes too great, a safety valve can be controlled to drain some of the water. If the water level becomes too low, the same circuit can control a pump to refill water.

Component List

Component	PCB Reference	Quantity	Looks Like
LM358 Op-Amp IC SOIC8	U1	1
100nF 0805 Capacitor	C1	1
100R 0805 Resistor	R1	1
1K 0805 Resistor	R2, R3	2
10K 0805 Resistor	R4, R5, R6, R7	4
100K SMD Potentiometer	RV1, RV2	2
0805 Red LED	D2, D3	2
1N5817 Diode SMD	D1	1
MMBT3904 NPN Transistor	Q1, Q2	2
Red Wire	VCC	1
Green Wire	VIN	1
Blue Wire	OUT	2
Black Wire	GND	2

PCB

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