Piezo Powered Lamp Schematic

Energy is becoming ever more expensive, and some fresh ideas are needed. There are already human-powered devices on the market, most of which employ a dynamo to generate power. It is also possible to recover energy from a piezo crystal of the sort found, for example, in the loudspeakers in greetings cards. Making use of this device is relatively straightforward. 

Piezo Powered Lamp Schematic Circuit Diagram

 

Piezo crystals can generate voltages of many tens of volts when given a firm enough prod with a finger to bend the baseplate. The charge moved, however,is relatively small and the crystal is effectively a capacitor with a capacitance of only around 20 nF to 50 nF. This means that we need larger-scale storage in the form of an electrolytic capacitor.

The piezo crystal can be treated as an alternating current source. We therefore need a rectifier and a reservoir capacitor. Pressing the metal surface of the transducer ten or twenty times with a finger will charge the electrolytic in steps to the point where it has enough charge to drive a LED. The circuit is a ‘charge pump’ in the full sense of the term.

When the button is pressed the electrolytic discharges into the LED, which emits a brief, but bright, flash of light.

 

Author :Burkhard Kainka  – Copyright :  Elektor

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Converter 12 Vdc to 230 Vac or Inverter

As shown in the Inverter circuit diagram obove , Its used as the oscillator stage astable multivibrator contained in IC1, a CMOS 4047 (this cult series 40xx series) by varying the resistance value of R1 trimmer (220 k total resistance) can vary the oscillation frequency of 40 Hz to 70 Hz square wave, phase shifted by 180 °,  Output pin 10-11 will drives two NPN transistors TR1-TR3, which in turn is fed to the TR2-TR4.

Converter 12 Vdc to 230 Vac or Inverter Schematic

The diodes DS2-DS3, mounted on the output transistors TR2-TR4 are used to protect against voltage surges appearing across the windings V 9 + 9 V transformer T1. For the transformer T1, I used an ordinary mains transformer (primary 230 V so) with a secondary dual 2 x 9 V.

Parts List:
R1 ……. 220 k trimmer
R2 ……. 330 k
R3 ……. 680
R4 ……. 2.2 k
R5 ……. 2.2 k
C1 ……. 4.7 nF polyester
C2 ……. 220 uF electrolytic
DS1 ….. 1N4004
DS2 ….. 1N4004
DS3 ….. 1N4004
DL1 ….. LED
TR1 ….. BC184 NPN
TR2 ….. NPN BDX53C
TR3 ….. BC184 NPN
TR4 ….. NPN BDX53C
IC1 …… 4047 CMOS
T1 …….. transformer sector 80 VA primary 230 V 0.35 A / Secondary 2 x 9 V 3.5 A
S1 ……. switch

Note :

• Two final power TR2-TR4 should be mounted on the right size heatsink, otherwise they will overheat. You can choose from MJ4033 – MJ3007 or more, provided that the NPN.
• The maximum power output that can be used depending on the size of the core of the transformer T1, the VA is: with 50 VA can be taken in the secondary 230 V 0.2 A (current consumed by the end will be 4 A) with 90 VA can be taken on the secondary 230 V 0.4 a (current consumed by the end will be 7 A).
• To power the circuit from the 12V battery, it will take over at least 1.8 millimeters in diameter, to avoid loss by Joule effect.

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Auto-off for Audio Gear

A good way to spend a relaxing afternoon is to be in a quiet place with just the right amount of sun or shade, drinks within reach and listening to your favourite songs on MP3 or CD. You doze off and by the time you wake up again the audio equipment has dropped silent due to flat batteries. What a pity!

The simple circuit shown can prevent this embarrassing situation by de-actuating a relay when no audio signal is detected for about two seconds.

Auto-off for Audio Gear Circuit Diagram

The circuit consists of a sensitive LM358 based comparator, IC1A, which keeps monostable IC2A (a 4538) triggered as long as an audio signal is detected at the input. Via coupling capacitor C1 the circuit takes its input signal from the ‘hot’ side of the loudspeaker or headphones in your audio gear. The monostable will time out 2 s after being triggered, the delay being deter-mined by R6 and C3.

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12V DC to 120V AC Inverter

Ever needed a low power 120volt AC  power source for your car, van or truck? Well this circuit should do the trick for you. It will supply 15 watts of AC power to a device. It should power lamps, shavers, small stereos and small appliances. If you draw to much power the circuit will shut down all by itself.

12 Volt DC to 120 Volt AC Inverter Circuit Diagram

The output of this circuit is a square wave so there may be some noticeable hum on audio units plugged into it. To reduce some of the hum increase the value of the output capacitor which is at .47uf now. That transistor in the circuit are high power PNP transistors. Radio Shack part number 276-2025 are good ones to use or TIP32. The transformer is a 24 volt 2 amp center tapped secondary Radio Shack part number 273-1512 or equivalent.

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Simple Light Sensitive Alarm

The circuit detects a sudden shadow falling on the light-sensor and sounds the bleeper when this happens. The circuit will not respond to gradual changes in brightness to avoid false alarms. The bleeper sounds for only a short time to prevent the battery running flat. Normal lighting can be used, but the circuit will work best if a beam of light is arranged to fall on the light-sensor. Breaking this beam will then cause the bleeper to sound. The light sensor is an LDR (light-dependant resistor), this has a low resistance in bright light and a high resistance in dim light.

Simple Light Sensitive Alarm Circuit Diagram

The light-sensitivity of the circuit can be adjusted by varying the 100k preset.

The length of bleep can be varied from 0.5 to 10 seconds using the 1M preset.

Using the 7555 low-power timer ensures that the circuit draws very little current (about 0.5mA) except for the short times when the bleeper is sounding (this uses about 7mA). If the circuit is switched on continuously an alkaline PP3 9V battery should last about a month, but for longer life (about 6 months) you can use a pack of 6 AA alkaline batteries.

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