70interesting circuits

In the process of bringing these faults and corrections to you, we have created this eBook of 70 Interesting Circuits.

common circuits

Another "set of eyes" will see things differently and maybe simplify or improve the design. The MPS-A18 is a very high gain transistor with excellent gain at very low currents. An LED will flash to indicate the lightning flashes.

easy electronic circuits to build

It is surprising that a magazine with a readership of over 1, could publish items with glaring faults. This is what happens.

Electronic circuit projects

It uses a twostage amplifier, a rectifier stage and an operational amplifier in inverting mode. We have already presented a set of pages called "Spot The Mistake," showing dozens of faulty circuits and how to check and test things before releasing them. The approximate impedance increase will be about Another "set of eyes" will see things differently and maybe simplify or improve the design. Only one of the current carrying lines, either the line or the neutral should be put through the center of the pickup to avoid the fields cancelling. If you wish to use the BAR mode, connect pin 9 to the positive supply rail, but obviously with increased current consumption. The original circuits come from an Indian Electronics Magazine and most of them had faults. We have already presented a set of pages called "Spot The Mistake," showing dozens of faulty circuits and how to check and test things before releasing them. Positive feedback ensures the LED to be full on. This parallel-tuned tank circuit is coupled to the base of Q1 via D2. This is basically a Schmitt Trigger which receives input from a cadmium sulfide photo cell and controls a relay that can be used to switch a lamp on and off at dawn and dusk. The circuit consists of a number of "building blocks" and the first consists of two transistors in a very clever "bootstrap" arrangement. If a transformer is rated at 1A, this is an AC rating and must be de-rated to mA for your power supply. The two diodes in the circuit below are needed to drop an additional 1v so the transistor turns off.

The capacitors are not particularly critical but the trimmer might require a little care. The transmitter circuit generates an ultrasonic frequency between kHz.

Circuits for the hobbyist

The photo cell should be shielded from the lamp to prevent feedback so the lamp light does not strike the photo cell and switch off the lamp. The inverted output of 1C2 is used to bias transistor Q5. As with any other remote control, the system basically comprises a transmitter and a receiver circuit. It uses ultrasonic sound waves for remote control of a switch. This design is optimized for capacitors less than about n. The magnetic pickup produces about 4 millivolts for AC line current of mA, or AC load of around 30 watts. When the lowest count is reached the latch is reset high so that the counter will begin incrementing on the next rising clock edge. The original circuits come from an Indian Electronics Magazine and most of them had faults. The original circuits come from an Indian Electronics Magazine and most of them had faults. Check that Led 1 lights up at approximately The LED brightness can be adjusted by choosing a different value for the 5k6 resistor connected at pin 6 and 7. A 9v adapter can be used to power the receiver circuit.

Transistor Q2 conducts and provides sufficient base drive to transistor Q3. The circuit consists of a number of "building blocks" and the first consists of two transistors in a very clever "bootstrap" arrangement.

555 circuits

Under dark conditions, the photo cell resistance will be high producing a voltage on the base of Q1 that is higher than the base voltage on Q2. The MPS-A18 is a very high gain transistor with excellent gain at very low currents. We have already presented a set of pages called "Spot The Mistake," showing dozens of faulty circuits and how to check and test things before releasing them. Current is detected by passing on of the AC lines through an inductive pickup L1 made with a 1 inch diameter U-bolt wound with turns of 35 magnet wire. Now we put a resistor from output to "-. Only one of the current carrying lines, either the line or the neutral should be put through the center of the pickup to avoid the fields cancelling. Either they were over-designed, poorly designed or contained a fault. If another door opens before the first door is closed, there is another beep and another LED lights. The circuit below shows the necessary components. This circuit is a bad design and is not recommended. The amplified signal are then rectified and filtered. The 2R2 will overcharge the battery and dry it out in a few months. One diode could be placed in the supply line to the if it is needed for the reset line to work correctly. The receiver is always kept on. Thus it indicates when the circuit is operating.

When transistor Q5 conducts, it supplies base bias to transistor Q6. When the next cycle is delivered to the transformer the core is already nearly saturated and it will become over-saturated and the transformer will heat up.

Interesting electronic circuits

It only takes a minute to see a circuit will not work and a few more minutes to create a improved design. The can supply 10mA to a LED on a 12v supply so that none of the transistors are needed. It is really a fascinating phenomenon. When the lowest count is reached the latch is reset high so that the counter will begin incrementing on the next rising clock edge. The two transistors remain in this state for a few seconds while the 2u2 discharges and the voltage on the base of the first transistor rises. When the potentiometer is at the lower position, the capacitor will charge through both 1k resistors and the 50k potentiometer and discharge through the lower 1k resistor, producing a long positive interval and short negative interval which brightens the lamp to near full intensity. If you wish to use the BAR mode, connect pin 9 to the positive supply rail, but obviously with increased current consumption. This circuit will simply not work and the relay will simply become a "Buzzer. The magnetic pickup produces about 4 millivolts for AC line current of mA, or AC load of around 30 watts. The output constant current I out is given by: The LED lights up only when a load is connected at the output. It uses ultrasonic sound waves for remote control of a switch. Thus, a five stage sequencer can be made by connecting pin 15 to pin 1.

Adjust it for maximum performance. This circuit will simply not work and the relay will simply become a "Buzzer.

bc547 circuit

Diode IN is necessary for the safety of the IC.

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