To generate regulated ± 5-V supplies from a pair of dry batteries, the circuit of Fig. 1 is commonly used. In order to give protection from inadvertent reverse connection of a battery, a diode in series with each battery would produce an unacceptable voltage drop. The more effective approach is to fit diodes Dl and D2 as shown in Fig. 2, in parallel with each battery. When the supply is switched off, there is the risk of a reverse bias being applied across the.....
The unit consists of a sensor, timer, and electric water pump. The sensor is embedded in the soil, and when dry, the electronics operate the water pump for a preset time. The circuit is composed of a level sensitive Schmitt trigger, variable time monostable, and output driver. When the resistance across the probe increases beyond a set value (ie, the soil dries), the Schmitt is triggered..
One small spot of rain on the sense pad of this bleeper will start this audio warning. It can also be operated by rising water. The circuit has two transistors, with feedback via capacitor Cl, but Trl cannot operate as long as the moisture sense pad is dry. ..
When the soil is moist, the LED glows. If the moisture falls below a certain predetermined level, the LED begins to flash. If there is still less moisture, the LED turns off. To calibrate, connect the battery and insert the probe into a container of dry soil. Set R1 to its maximum value then reduce that resistance until the LED begins to flash...
This thing is a very nifty capacitive sensor. For you europeans, this little gem is used in north america mostly for detecting wooden beams behind drywall or plaster. I`ll take one of these over the new design any day, because these ones don`t error out every time you try to use them in a non-standard way...
This circuit is a church bell controller. Basic component is an ATmega32 microcontroller. At the circuit 2 24LC32 eeprom memories is being used, the 1st for internal standard melodies and the 2nd one is for user's compositions. This feature will be provided in the future. As control I created a menu who will be appeared on 4x20 LCD (Liquid Crystal Display). The menu browsing can be done by 6 buttons at the face of the circuit's box (Menu, Up, Down, Enter, Start, Stop). The.....
The JavaBot1 is a small line following robot designed to follow a black line drawn on a dry erase board. It is designed to follow very tight curves. The software still has lot`s of room for improvement but works well as is. The JavaBot1 uses 2 Cirrus CS-70 servos that have been modified for full rotation and have had their controller boards removed to convert them from servos to gear motors. Servos are a common motive power for small robots due to their low cost, ready.....
This spring reverberation unit comprises three identical main sections each of which contains an Accutronics type 9 spring reverb tank with short, medium and long decay times. Controls are provided to adjust the amount of signal arriving at the output from the input directly and from the spring tank. Conventionally these signals are called "dry" and "wet." A feedback control allows the tank output to be returned to the tank input to produce oscillation effects. The.....
He called this device the Stromerzeuger and for a few watts from a dry battery it provided 6 kW continuously. He was refused development support because it was a perpetual motion machine. Hans also invented a passive device which he called the Magnetstromapparat. His unit required very careful and slow adjustment to get it operating but when it started it continued on test in a locked room for three months of continuous operation...
Firstly, we will describe the "add-on" version for the 5x7 Display as this is the cheapest version and, quite frankly, it only deserves a few dollars as a piece of test equipment. It`s "all the rage" to have an Electrolytic Tester for servicing equipment and yet I have serviced over 36,000 appliances without one. Possibly it took me a long time to realise electrolytics have the capability of drying out because old-style electros were inherently very reliable and,.....
This is a very simple circuit that can be used to test whether a pot is dry or not. When the two probes are inserted in wet soil, then the resistance between the sensors are low. The base of T1 will therefore be more negative and the LED is not lit. However, when the soil is dry, its resistance will be high and will base more positive. ..
The circuit diagram of the Lie Detector is shown above. It consists of three transistors (TR1 to TR3), a capacitor (C1), two lights or LEDs (L1 & L2), five resistors (R1 to R5), and a variable resistor (VR1). This circuit is based on the fact that a person`s skin resistance changes when they sweat (sweating because they`re lying). Dry skin has a resistance of about 1 million ohms, whereas the resistance of moist skin is reduced by a factor of ten or more...
This simple circuit will find many applications as a battery eliminator for low power requirements. It consists of a transformer, a bridge rectifier and an electrolytic capacitor followed by a zener controlled series pass transistor. The output is stabilized at +7.5V. The stand-by battery, 7.5V, in series with D7, floats across the output terminals, ready to take over in case of main failure. The voltage drop across D7 will then reduce the power supply to about 7V. The R3.....
The Project presented here waters your plants regularly when you are out for vocation. The circuit comprises sensor parts built using op-amp IC LM324. Op-amps are configured here as a comparator. Two stiff copper wires are inserted in the soil to sense the whether the Soil is wet or dry...
This circuit is for a temperature controlled constant current battery charger. It works with NICD, NIMH, and other rechargeable cells. The circuit works on the principle that most rechargeable batteries show an increase in temperature when the cells becomes fully charged. Overcharging is one of the main causes of short cell life, hot cells pop their internal seals and vent out electrolyte. As cells dry out, they lose capacity...
This circuit is a church bell controller. Basic component is an ATmega32 microcontroller. At the circuit 1 24LC32 eeprom memories is being used. As control I created a menu who will be appeared on 4x20 LCD (Liquid Crystal Display). The menu browsing can be done by 6 buttons at the face of the circuit's box (Menu, Up, Down, Enter, Start, Stop). The all firmware binds about 30Kbytes flash memory and can be increased by adding new features-functions. This program has been.....
The circuit of a battery operated portable miniature strobe light, which can be constructed using readily available inexpensive components, is described here. For convenience and simplicity, an ordinary neon lamp is used here in place of the conventional Xenon tube. The whole gadget can thus be easily accommodated in a small cabinet, such as a mains adaptor cover, with a suitable reflector for neon lamp to give a proper look. Since current requirement of this circuit is.....
The circuit uses a 555 timer wired as an astable oscillator and powered by the emitter current of the BC109C. Under dry conditions, the transistor will have no bias current and be fully off. As the probes get wet, a small current flows between base and emitter and the transistor switches on. A larger current flows in the collector circuit enabling the 555 osillator to sound...
Stick the metal probes into a freshly watered plant and adjust R5 for a mid-scale meter deflection. The meter will monitor the soil wetness and the meter will indicate whether it is to moist or to dry. This circuit uses a dual power supply which could be created by two 9 volt batteries...
Operational Amplifiers
Computer Systems
Oscilloscopes
Transmitters & Receivers
Sensors & Detectors
ANSI Standards
Low Frequency Amplifiers
Power Amplifiers
Number Systems
Regulated Power Supplies
Analogue Filters
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