Tuesday, April 30, 2013
AC 230V Led Circuit Diagram by DIAC
Tthis is a very simple LED flasher circuit diagram that is powered from AC 230V mains. This Flasher can be used as a power indicator for the AC 230V mains supply. This circuit is made with few numbers of parts namely, a LED, two Resistors, one Capacitor, one Diode and one DIAC. The DIAC act the main role to flashing the LED. DIAC is a bidirectional device. It conducts current only after its breakover voltage has been reached its threshold. Most DIACs breakover voltage is around 30 V.
230V Mains Power Indicator LED Flasher Circuit Diagram
When mains is connect to the circuit, the Capacitor(C1) starts charging through Diode(D1)&Registor(R1). When the voltage on the capacitor reached the DIAC’s threshold voltage, the DIAC get turn on. And LED gets Lights(flash). At the same time Capacitor(C1) goes discharges and breakover voltage of DIAC also decrease and LED turns OFF. The on off time of the LED depends on the value of Capacitor(C1) and Resistor(R1).
Note that the flashing time of the LED shown in the animating figure is not the exact timing of ON/OFF.
Copyright : CircuitsTune.com
Copyright : CircuitsTune.com
Car Interior Lights Delay
Most cars do not have delayed interior lights. The circuit presented can put this right. It switches the interior lights of a car on and off gradually. This makes it a lot easier, for instance, to find the ignition keyhole when the lights have gone off after the car door has been closed. Since the circuit must be operated by the door switch, a slight intervention in the wiring of this switch is unavoidable. When the car door is opened, the door switch closes the lights circuit to earth. When the door is closed (and the switch is open), transistor T1, whose base is linked to the switch, cuts off T2, so that the interior light remains off. When the switch closes (when the door is opened), the base of T1 is at earth level and the transistor is off.
Circuit diagram:
Circuit diagram:
Capacitor C1 is charged fairly rapidly via R3 and D1, whereupon T2 comes on so that the interior light is switched on. When the door is closed again, T1 conducts and stops the charging of C1. However, the capacitor is discharged fairly slowly via R5, so that T2 is not turned off immediately. This ensures that the interior light remains on for a little while and then goes out slowly. The time delays may be varied quite substantially by altering the values of R3, R5, and C1. Circuit IC2 may be one of many types of n-channel power MOSFET, but it should be able to handle drain-source voltages greater than 50 V. In the proto-type, a BUZ74 is used which can handle D-S voltages of up to 500 V.
Saturday, April 13, 2013
FINDING THE BASE and determining NPN or PNP
FINDING THE BASE and determining NPN or PNP
Get an unknown transistor and test it with a multimeter set to "x10"
Try the 6 combinations and when you have the black probe on a pin and the red probe touches the other pins and the meter swings nearly full scale, you have an NPN transistor. The black probe is BASE
If the red probe touches a pin and the black probe produces a swing on the other two pins, you have a PNP transistor. The red probe is BASE
If the needle swings FULL SCALE or if it swings for more than 2 readings, the transistor is FAULTY.
Get an unknown transistor and test it with a multimeter set to "x10"
Try the 6 combinations and when you have the black probe on a pin and the red probe touches the other pins and the meter swings nearly full scale, you have an NPN transistor. The black probe is BASE
If the red probe touches a pin and the black probe produces a swing on the other two pins, you have a PNP transistor. The red probe is BASE
If the needle swings FULL SCALE or if it swings for more than 2 readings, the transistor is FAULTY.
Phono Preamplifier Circuit
Simple circuitry, Passive high-frequency equalization
n recent years, following CDs introduction, vinyl recordings are almost disappeared. Nevertheless, a phono preamplifier is still useful for listening old vinyl discs from a well preserved collection. This simple but efficient circuit devised for cheap moving-magnet cartridges, can be used in connection with the audio power amplifiers shown in these web pages, featuring low noise, good RIAA frequency response curve, low distortion and good high frequency transients behavior due to passive equalization in the 1 to 20 KHz range.
Phono Preamplifier Circuit diagram:
R1 = 47K
R2 = 100R
R2 = 6.8K
R4 = 68K
R5 = 2.7K-1/2W
R6 = 2.7K-1/2W
R7 = 2.2K
R8 = 39K
C1 = 100uF-25V
C2 = 100uF-25V
C3 = 100uF-25V
C4 = 47nF-63V
C5 = 47nF-63V
D1 = BZX79C18
D2 = BZX79C18
Q1 = BC337
Q2 = BC327
J1 = RCA Jack
IC1 = LM833, Opamp
Notes:
- R2, R3, R4, R7, R8, C4 & C5 should be low tolerance types.
- Schematic shows left channel and power supply.
- For stereo operation R1, R2, R3, R4, R7, R8; J1; C1, C4 & C5 must be doubled.
- Numbers in parentheses show IC1 right channe
Source : http://www.ecircuitslab.com/2011/06/phono-preamplifier-circuit.html
Voltage to current converter with floating load
The current in the feedback loop depends on the voltage and Ri.
This applications where we need to pass a constant current through a
load and hold it constant despite any changes in load resistance or load
voltage. When the load does not have to be grounded, we simply place
the load in the feedback loop and control both input and load current from this circuit.
This applications where we need to pass a constant current through a
load and hold it constant despite any changes in load resistance or load
voltage. When the load does not have to be grounded, we simply place
the load in the feedback loop and control both input and load current from this circuit.
This circuit shown in figure voltage to current converter
with floating load. The voltage to current converter can be used in
such applications as low voltage dc and a voltmeters, diode match
finders light emitting diodes (LEDS) and zener diode tester.
with floating load. The voltage to current converter can be used in
such applications as low voltage dc and a voltmeters, diode match
finders light emitting diodes (LEDS) and zener diode tester.
This circuit diagram Figure shows a voltage to current converter in which load resistor RL is
floating (not connected to ground). The input voltage is applied to the
no inverting input terminal and the feedback voltage cross R1 drives the inverting input terminal. This circuit is also called a current series negative feedback amplifier because the feedback voltage across R1 (applied to the inverting terminal) depends on the output current i0 and is in series with the input difference voltage vid.
floating (not connected to ground). The input voltage is applied to the
no inverting input terminal and the feedback voltage cross R1 drives the inverting input terminal. This circuit is also called a current series negative feedback amplifier because the feedback voltage across R1 (applied to the inverting terminal) depends on the output current i0 and is in series with the input difference voltage vid.
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