voltage stepper

In conventional voltage multiplier circuits, AC is used to charge the capacitors network via diodes in one cycle and discharge in the other cycle in a particular combination, which thereby produces multiples of the peak voltage. However, this circuit works on a different principle, and it is DC which is doubled. It can be used to power low current circuits.

IC555 is configured as an astable multivibrator producing rectangular pulses of about 10kHz frequency. Its output is made to drive the transistor pair T₁ and T₂. Transistor T₂ being a pnp type, conduct when its base is negative, i.e. when the output of the IC produces a “low”. This charge C₄ via diode D₁ and ground (collector of T₂ is grounded).

For the next pulse, i.e. when the output of IC is high, T₁ conducts but T₂ is cut-off, C₄ cannot discharge because of diode D₁. So the voltage across C₄ and input voltage adds up and charge C₅ via D₂. Voltage across C₅ will equal Vcc pulse voltage across capacitor C₄ and Diode D₁. Hence the operation.

However, it was found that if current greater then 50 mA and drawn, output voltage, hence regulation, is lost. Any DC voltage between 5V and 18V can be boosted (both voltage being the minimum and maximum range of the IC).

For better results, increase the value of C₄ and C₅ to 47 µF/40V.

PARTS LIST

Resistors (all ¼-watt, ± 5% Carbon)

R₁ = 220 Ω

R₂ = 6.8 KΩ

..Read more https://electronicsproject.org/voltage-stepper/

Rain Alarm

Rain Alarm

The following rain circuit is used to give an alert when it’s going to rain. This circuit is used in homes to guard their washed clothes and other things that are vulnerable to rain when they stay in the home most of the time for their work. The required components to build this circuit are probes. 10K and 330K resistors, BC548 and BC 558 transistors, 3V battery, 01mf capacitor and speaker.

Rain Alarm

Whenever the rainwater comes in contact with the probe in the above circuit, then the current flows through the circuit to enable the Q1 (NPN) transistor and also Q1 transistor makes Q2 transistor (PNP) to become active. Thus the Q2 transistor conducts and then the flow of current through the speaker generates a buzzer sound. Until the probe is in touch with the water, this procedure replicates again and again. The oscillation circuit built in the above circuit that changes the frequency of the tone, and thus tone can be changed.

Invisible Burglar Alarm

Invisible Burglar Alarm

The circuit of the invisible burglar alarm is built with a photo transistor and an IR LED. When there is no obstacle in the path of infrared rays, an alarm will not generate buzzer sound. When somebody crosses the Infrared beam, then an alarm generated buzzer sound. If the photo transistor and the infrared LED are enclosed in black tubes and connected perfectly, the circuit range is 1 meter.

Invisible Burglar Alarm

When the infrared beam falls on the L14F1 photo transistor, it performs to keep the BC557 (PNP) out of conduction and the buzzer will not generate the sound in this condition. When the infrared beam breaks, then the photo transistor turns OFF, permitting the PNP transistor to perform and the buzzer sounds. Fix the photo transistor and infrared LED on the reverse sides with correct position to make the buzzer silent. Adjust the variable resistor to set the biasing of the PNP transistor.Here other kinds of photo transistors can also be used instead of LI4F1, but L14F1 is more sensitive.