USB Devices Charger Circuit

If you are in the traveling, you may be need this device to charge your gadget along the way, since it is much cheaper to buy some standard AA batteries for backup than buying several rechargeable batteries of your gadget type. Below is a charger that more efficient than linear regulator like the “7805″ while you are on the go. The most important component on this device is the “LT1301″. This is a small step up converter for to build switching mode power supply with only a few external components. This is the figure of the circuit;


To build this device, you need a LT1301 and a ic socket (8DIP), 2 electrolyte caps WITH! low ESR (6,3V 100uF), one inductor with a very LOW! DCR (around 0,03R) with 10uH should be able to handle switching currents at about 1,5 Amperes, one schottky rectifier like “SB130″ or “1N5817″ (important if you can’t get one of the two proposed rectifiers: low forward voltage drop, fast switching capability and it should be able to handle currents of 1 Ampere.), and A switch(on/off), an USB connector, a circuit board, a LED with resistor (limit led current to 2mA!, don’t loose your mA by pumping them through the LED) and don’t forget the battery holder.

Servo Motor System Controller Circuit

This is a design circuit for a Servo System Controller circuit. This circuit is used to control a servo motor remotely. This circuit uses the 555 and requires only six extra components. This is the figure of the circuit;


[Schematic circuit source: Philips Semiconductors Application Note]

Decibel Sound Pressure Level Meter Circuit

This is a design for decibel meter circuit. This circuit is used to measure sound pressure level (SPL) from about 60 to 70 dB. In this circuit, the transistor stage and one LM324 op-amp section are used to amplify the sound that is picked up by an 8 ohm speaker. As voltage comparators, the circuit uses The remaining 3 sections of the LM324 quad op-amp. 3 indicator LEDs are driven by the LM324. This is the figure of the circuit;


This circuit uses 3 LEDs as indicators. Each LED represents about a 3dB change in sound level, so that when all 3 LEDs are on, the sound level is about 4 times greater than the level needed to light one LED. the 500K pot can be used to adjust the sensitivity of the circuit. One LED is used as a reference sound level. The other two LEDs is used to indicate about a 2X and 4X increase in volume.

Audio Amplifier Circuit with DC Volume Control

This is a design circuit for audio power amplifier. This circuit uses based on TDA7052B. The TDA7052B and TDA7052BT are 0.5 W and 1 W mono Bridge-Tied Load (BTL) output amplifiers with DC volume control. Not only have been designed for use in TV and monitors, but TDA7052B and TDA7052BT are also suitable for use in battery-fed portable recorders and radios. This is the figure of the circuit;


This devices are integrated with a Missing Current Limiter (MCL). When the difference in current between the output terminal of each amplifier exceeds 100 mA (300 mA typ), the MCL circuit is activated. Headphone application will be allowed on this 100mA level (single-ended).
[Circuit source: NXP Application Note]

Digital Step Km Counter Circuit

This circuit is designed for measures the distance covered during a walk. Hardware is located in a small box slipped in pants' pocket and the display is conceived in the following manner: the leftmost display D2 (the most significant digit) shows 0 to 9 Km. The rightmost display D1 (the least significant digit) shows hundred meters and its dot illuminates after every 50 meters of walking. A beeper (excludable), signals each count unit, occurring every two steps. This is the figure of the circuit;

This circuit has operation with based on 2 IC. IC1A & IC1B form a mono stable multi vibrator providing some degree of freedom from excessive bouncing of the mercury switch. Therefore a clean square pulse enters IC2 that divides by 64. Q2 drives the LED dot-segment of D1 every 32 pulses counted by IC2. Either IC3 & IC4 divide by 10 and drive the displays. P1 resets the counters and P2 enables the displays. IC1C generates an audio frequency square wave that is enabled for a short time at each mono stable count. Q1 drives the piezo sounder and SW2 allows to disabled the beep.

A normal step was calculated to span around 78 centimeters, thus the LED signaling 50 meters illuminates after 64 steps (or 32 operations of the mercury switch), the display indicates 100 meters after 128 steps and so on. For low battery consumption the display illuminates only on request, pushing on P2. Accidental reset of the counters is avoided because to reset the circuit both pushbuttons must be operated together.

Part:

R1,R3____22K 1/4W Resistor

R2________2M2 1/4W Resistor

R4________1M 1/4W Resistor

R5,R7,R8__4K7 1/4W Resistor

R6_______47R 1/4W Resistor

R9________1K 1/4W Resistor

C1_______47nF 63V Polyester Capacitor

C2______100nF 63V Polyester Capacitor

C3_______10nF 63V Polyester Capacitor

C4_______10µF 25V Electrolytic Capacitor

D1_______Common-cathode 7-segment LED mini-display (Hundreds meters)

D2_______Common-cathode 7-segment LED mini-display (Kilometers)

IC1______4093 Quad 2 input Schmitt NAND Gate IC

IC2______4024 7 stage ripple counter IC

IC3,IC4__4026 Decade counter with decoded 7-segment display outputs IC

Q1,Q2___BC327 45V 800mA PNP Transistors

P1_______SPST Pushbutton (Reset)

P2_______SPST Pushbutton (Display)

SW1______SPST Mercury Switch, called also Tilt Switch

SW2______SPST Slider Switch (Sound on-off)

SW3______SPST Slider Switch (Power on-off)

BZ_______Piezo sounder

B1_______3V Battery (2 AA 1.5V Cells in series)

8 Channel Running Light Circuit

This is a simple application that can be used for modern home. This circuit is used 2 IC. This circuit used 7475 quad latch IC. This is the figure of the 8 channel running light circuit;

This circuit can be used to bore unwanted guest, like pats, etc. LEDs are driven by the outputs of the four latches from the IC.