This circuit is intended as a reliable replacement to thermally-activated switches used for Christmas tree lamp-flashing. The device formed by Q1, Q2 and related resistors triggers the SCR. Timing is provided by R1,R2 & C1. To change flashing frequency don’t modify R1 and R2 values: set C1 value from 100 to 2200uF instead. Read the rest of this entry »
If you want to test someone telling you the truth or not, you can use this simple lie detector. It’s easy to build. You need transistor, electrode, resistor, capacitor and analog ampere meter. This lie tester works by measuring skin resistance which goes down when you lie. For electrodes, you can use alligator clips, electrode pads, or just wires and tape.
To use the circuit, first, attach the electrodes to the back of the subjects hand, about 1 inch apart. Secondly, adjust the meter for a reading of 0. Ask simple questions that you know he lying or not for calibration. After that ask your main question. You know the subject is lying when the meter changes. Read the rest of this entry »
During testing circuit, it’s difficult use LED as indikator of logic probe. Another good option is using Audible Logic Probe. With this probe, Any input greater then 2 volts will be high and output a high tone through the speaker. Any input less then .8 volts will be low and produce a low tone through the speaker.
Using this circuit you can convert the 12V dc in to the 220V Ac. In this circuit 4047 is use to generate the square wave of 50hz and amplify the current and then amplify the voltage by using the step transformer.
Attention: This Circuit is using high voltage that is lethal. Please take appropriate precautions
How to calculate transformer rating Read the rest of this entry »
Most car battery chargers are simple devices that continuously charge the battery with a few amperes for the duration it is ON. If the charger is not switched OFF in time, the battery will overcharge, its electrolyte lost due to evaporation, and its plate-element will likely be destroyed.
The circuit above will eliminate these problems by monitoring the battery’s condition of charge through its retroactive control circuit by applying a high charge current until the battery is completely charged. When charging is complete, it turns on the red LED (LD2) and deactivates the charging circuit. This circuit is drawn to charge 12V batteries ONLY. Certain emphasis should be taken when wiring up this circuit. They are the connections of the transformer to the circuit board, and those supplying current to the battery being charged. These connections should be made with cables having a large cross-sectional area to prevent voltage-drop and heat build-up when current flows through them. Read the rest of this entry »
This Audio amplifier has output 18 Watt RMS into 8 Ohm (1KHz sine wave) and Frequency response 30Hz to 20KHz -1dB. It’s simple to build and you don’t need preamplifier. Few notes about this circuit.
Protection in electronic circuits is crusial factor. especially polarity reverse protection. Can you imagine what happen if our circuit not pretected to reverse polarity supply. All digital IC will be damage, and also electrolit capacitor will blow up. via circuit electronic
This is may be the simplest radio transmitter that you will find anywhere. lt has a total of fiye parts and can be constructed into a very small space. It is great for science fair projects or other science related projects where short range transmission is useful. via electronic circuit