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TOUCH SWITCH 1 This circuit detects the skin resistance of a finger to deliver a awfully tiny current to the super-alpha try of transistors to show the circuit ON. The output of the "super transistor" activates the BC 557 transistor. The voltage on the highest of the world is passed to the front of the circuit via the 4M7 to require the place of your finger and also the circuit remains ON.  To turn the circuit OFF, a finger on the OFF pads can activate the primary transistor and this may rob the "super transistor" of voltage and also the circuit can close up. TOUCH SWITCH-2 This circuit detects the skin resistance of a finger to show the circuit ON for concerning one second. The output are often taken to a counting circuit. The circuit consumes no current when in quiescent mode:

This led series will Blinking alternately, The way it works is determined by IC NE555 and transistors are used as reinforcement for each section (20 upper, 20 lower) work optimally. 555 circuit below is a flashing bicycle light powered with four C, D or AA cells (6 volts).  Two sets of 20 LEDs will flash alternately at about 4.7 cycles per second using RC values ​​shown (4.7K for R1, 150K for R2 and 1uF capacitor). Time intervals for two lights about 107 milliseconds (T1, LED on) and 104 milliseconds (T2 lower LEDs).  Two transistors are used to provide additional time beyond the current limit of 200mA from the NE555 timer. A single LED is placed in series with the PNP transistor base so that the 20 LED 555 is turned off when the output is high during a time interval T1. High-level output timer 555 is 1.7 volts less than the supply voltage. Adding the LED forward voltage increase is required for the PNP transistor to about 2.7 volts, so the 1.7 volt difference from the supply ...

A protector system that is applied at the beginning of the television technique, therefore most often found on old aircraft models. If the high voltage anode of the picture tube flyback tranfo exceed the permitted limit, the picture tube can generate x-rays from the anode and shadowmask are bombarded by electrons at high speed. To avoid this problem then mounted x-ray surge protector circuit , which automatically "horizontal section will be turned off" if the high voltage from the flyback over. X-Ray vertical protect The workings of x-ray protector: High voltage flyback sampled (generally taken from the pin-heater), rectified and is derived using a divider (devider) that uses a resistor-type high-precision resistor. Sample voltage is used to determine whether the condition is normal flyback voltage or over. A "zener diode" as a voltage sensor connected to the sample. In normal conditions the amount of the sample voltage is below the zener voltage of diode so that th...

These circuits only flash one or two LEDs. This is opposed to the light chaser circuits that can flash four or more. Of course, the simplest LED flasher is simply to use a flashing LED . The problem with that approach is you have no control over the flash rate, but it does have its use for eye catching displays for selling stuff. The circuits below give you that control, plus they can flash two LEDs alternately. There are many possible applications for the circuits below, especially for kids, who love flashing lights. Here's some possible uses. Railroad crossing signal for model railroads. Safety blinkers for bicycles, etc. Fun stuff for Halloween, like making those plastic Jack-O-lanterns blink (try using ultraviolet LEDs here). Christmas decorations. Blinkers to locate items in the dark. Transistor LED flasher This circuit has a lot going for it. For one thing, it only consists of two transistors , two capacitors and four resistors . That also means it consumes very little ...

L297 Stepper Motor Controller Circuits Four appearance drive signals for two appearance bipolar and four appearance unipolar footfall motors in microcomputer-controlled appliance is calmly implemented application L29 Stepper Motor Controller IC. We can drive the motor in bisected step, accustomed and beachcomber drives approach and switch-mode ascendancy of the accepted in the windings is permuted on dent PWM chopper circuits. This accessory has some appearance like it requires alone clock, administration and approach ascribe signals. Since the appearance are produced internally the accountability on the microprocessor, and the programmer, is decidedly reduced. This accessory is army in DIP20 and SO20 packages. We can use L297 with caked arch drives such as L293E or L298N, or we additionally can use it with detached transistors and Darlingtons.