A very simple low cost water level indicator circuit can be designed using this schematic circuit . This water level indicator is based on a simple CMOS IC CD4066 and indicates the amount of water present in the overhead tank and also gives an alarm when the tank is full. As you can see in the circuit diagram the circuit uses the widely available CD4066, bilateral switch CMOS IC to indicate the water level through LEDs.

Water Level Indicator Using CMOS ICs Circuit Diagram:



When the water is empty the wires in the tank are open circuited and the 180K resistors pulls the switch low hence opening the switch and LEDs are OFF. As the water starts filling up, first the wire in the tank connected to S1 and the + supply are shorted by water. This closes the switch S1 and turns the LED1 ON. As the water continues to fill the tank, the LEDs2 , 3 and 4 light up gradually.

The no. of levels of indication can be increased to 8 if 2 CD4066 ICs are used in a similar fashion.
When the water is full, the base of the transistor BC148 is pulled high by the water and this saturates the transistor, turning the buzzer ON. The SPST switch has to be opened to turn the buzzer OFF.

As you can see this electronic liquid sensor circuit require very few external components and need to be powered from a 6 volts DC power supply .

Here is a simple circuit for boosting 12 V DC to 24 V DC .The circuit is designed straight forward and uses few components.With few modifications the circuit can be used to boost any voltages.

The transistor Q1 and Q2 (D1616)  essentially drives the primary of the transformer.The diodes rectifies the output of transformer to obtain a 24V DC at the output load(here a fan).The capacitors filter away noise and harmonics away from the output.

Voltage Booster Circuit Diagram:



Notes:

• The component values are not very specific here.We can use any NPN power transistors like D1616,2N 3055,C2236,SL 100 etc for Q1 and Q2.
• The transformer can be any center tapped 5A transformer with a  7:1 winding ratio.
• The diodes can be 1N 914 ones.
• In fact you can easily assemble the circuit from the components in your electronics junk box.
• By experimenting on the tranformer winding you can get different boost ratios.
• For high current (around 5A)  games use 2N 3055 transistor or more powerful Darlington pairs for Q1 and Q2.

This is an electronic circuit project of  gsm jammer or mobile cell phone. This  jammer schematic diagram for use only in GSM1900 with frequency from 1930 MHz to 1990 MHz. The GSM1900 mobile phone network is used by USA, Canada and most of the countries in South America.

Mobile Cellphone Jammer Circuit Diagram:



This cell phone jammier is not applicable for use in Europe, Middle East, nor Asia. The GSM jammier circuit could block mobile phone signals which works on GSM1900 band, also called DCS. For more cell phone jammers check the related posts.

This is very interesting electronic project for gsm jammer. A wonderful diy gsm jammer or cellular mobile phone jammer schematic diagram for use only in GSM1900 with frequency from 1930 MHz to 1990 MHz.


Gsm Cell Phone Jammer Circuit Diagram:



The GSM1900 cellular cell phone network is made use of by USA, Canada and most of the nations in South America. This cellular phone jammer isn`t applicable for use in Europe, Center East, nor Asia. The GSM jammer circuit could block mobile mobile phone signals which operates on GSM1900 band, also identified as DCS.

A temperature sensor and a hot transistor hold biological samples at a preset temperature.

It is common to use transistors for driving resistive heating elements. However, you can use the heat that a power transistor dissipates to advantage in several situations, eliminating the need for a separate heating element because most transistors can safely operate at temperatures as high as 100°C. A typical example is in a biological laboratory, in which the need for maintaining the temperature of samples in microliter-sized cuvettes is a common requirement. The space/geometry constraint and the less-than-100°C upper-temperature limit are the basic factors of the idea.

Electronic Circuit Project Use a Transistor as a Heater:



Figure 1.
IC1 senses the temperature of the item that Q2 heats, and the temperature remains at the level that VR1 sets.

You can use an N-channel IRF540 MOSFET to directly heat and control the temperature of a biological sample from ambient to 45°C. Figure 1 shows a simple on/off-type control circuit in which an LM35, IC1, is the temperature sensor, whose output a DPM (digital panel meter) can display. IC2 compares the voltage that VR1 sets with the output of the LM35 to turn on Q2 accordingly, with the positive feedback through R9 providing a small amount of hysteresis. S1 switches the DPM between a set value and the actual temperature readout. You derive the reference voltage from a TL431 shunt regulator (not shown). The LED lights up when Q2 is on.

IC1 and Q2 thermally mount on the metal block that forms the sample holder; use thermal grease on both components for maximum heat transfer. Note that the mounting tab of the TO-220 package electrically connects to the drain, and you may need to insulate it from the cuvette with a thermal pad. Setting bias control VR3 for a Q2 current of 270 mA is sufficient to hold the cuvette at 45°C.

Be sure to set to minimum power during initial power-up; if you set it for maximum power, you could apply 24V to Q2’s gate-to-source voltage, which is rated for a maximum of only 20V. You can extend the temperature range by changing the voltage divider comprising R1, R2, and VR1. The design includes a safety cutoff circuit (not shown) in case the temperature gets too high.

Various other options are also possible applications for this circuit. These applications include linear control, pulse-width modulation, and the use of a PID (proportional-integral-derivative) controller, to name a few.