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Human detector circuit – Circuit Schematic
Human detector circuit
This is a circuit thich I originally included in my book, 22 Tested Transistor Projects, published by Babani Press in 1976 (ISBN 0 900162 63 S). It is one I had...
Room thermometer with LEDs – Circuit Schematic
Room thermometer with LEDs
This circuit uses a germanium diode (marked Ge) as a temperature sensor. I used an OA90 diode but others should do. The 'ring' of Tr1 and Tr2 bias each other. ...
Electronic Thermostat – Circuit Schematic
Electronic Thermostat
Here is a circuit that implements phase-control of heaters, adjusting their power smoothly from zero to around 95% of the rated power, keeping the room temperat...
Digital Compass for PC – Circuit Schematic
Digital Compass for PC
The digital navigation PC board may be configured for a number of navigation functions, see figure 1. It may be made into a simple visual digital compass, or a ...
Infra-red detector circuit – Circuit Schematic
Infra-red detector circuit
This circuit is a simple IR detector for testing IR remote controllers. The circuit is based on one phototransistor which receives the IR beam. The NPN transist...
Acceleration sensing USB interface – Circuit Schematic
Acceleration sensing USB interface
The TiltStick is a small acceleration sensing device in form of a USB stick. It's using a two axis acceleration sensor to measure acceleration (caused e.g. by m...
Light Barrier Detector – Circuit Schematic
Light Barrier Detector
This simple circuit using a single transistor turns ON the relay when light falls on the LDR. The potentiometer is adjusted for the required sensitivity. The ...
Color Sensor circuit – Circuit Schematic
Color Sensor circuit
Colour sensor is an interesting project for hobbyists. The cir- cuit can sense eight colours, i.e. blue, green and red (primary colours); magenta, yellow and cy...
Dew sensor circuit – Circuit Schematic
Dew sensor circuit
Dew (condensed moisture) ad- versely affects the normal per- formance of sensitive electronic devices. A low-cost circuit described here can be used to switch o...
Magnetic proximity sensor / detector – Circuit Schematic
Magnetic proximity sensor / detector
Here is an interesting circuit for a magnetic proximity switch which can be used in various applications. The magnetic proximity switch circuit, in principle, ...
infrared beam proximity detector – Circuit Schematic
infrared beam proximity detector
his circuit can be used as an Infrared beam barrier as well as a proximity detector. The circuit uses the very popular Sharp IR module (Vishay module can also ...
Barometer with Sensor Motorola MPX4115 – Circuit Schematic
Barometer with Sensor Motorola MPX4115
This design uses a Motorola MPX4115 Silicon Pressure Sensor, a Dallas Semiconductor DS2438 Smart Battery Monitor (to perform 1-Wire analog to digital conversion...
Altimeter Circuit – Circuit Schematic
Altimeter Circuit
The circuit is powered by the receiver's pack, the current drain is low, specially if compared to drain of servos. U1a VZ2 and Q1 are the CURRENT source of the...
Sun Light Chaser – Circuit Schematic
Sun Light Chaser
With RFT illuminated, point R goes to 0 volt and LM runs. With LFT illuminated, point R goes to 0 volt and RM runs. With RFT and/or LFT not illuminated, points ...
Simple Electric Field Detector – Circuit Schematic
Simple Electric Field Detector
The circuit will come handy when you have to follow the mains wires buried in the wall or even water pipes provided they are not too far away (2-4cm max). It wi...
Sensitive Geomagnetic Sensor circuit – Circuit Schematic
Sensitive Geomagnetic Sensor circuit
This is a rather sensitive circuit which will detect minute variations of a magnetic field, particularly the Earth magnetic field. The principle is based on an ...
Geomagnetic Field Detector circuit – Circuit Schematic
Geomagnetic Field Detector circuit
This basic oscillator will detect the Earth magnetic field. The ferrite rod and coil are taken from an old Medium Wave receiver and a small magnet is glued at o...
Heat sensor relay switch – Circuit Schematic
Heat sensor relay switch
The Thermistor, or NTC (Negative Temperature Coefficient) of 10K, is a standard type. Most types will work. The one in the diagram is a 10K model made by Fenwa...
Negative Ions Detector / Sensor – Circuit Schematic
Negative Ions Detector / Sensor
Ions are defined as electrically charged atoms. Positively charged ions have a deficiency of electrons, and negatively charged ions have a surplus of electrons....
Temperature Fan Controller – Circuit Schematic
Temperature Fan Controller
This circuit controls very accurately a fan of any size. Just adjust the associated resistors for a different type like the R6 resistor of 100 ohm, 2 watt type ...