Showing posts with label controlled. Show all posts
Showing posts with label controlled. Show all posts
Thursday, August 14, 2014
Single Phase Full wave Controlled Rectifier CKT
In the Given ckt a Single phase controlled Rectifier is shown which is used to control the DC motor speed. This ckt is consisting of four SCR and four Diodes. The DC voltage is supplied to the motor winding through four diodes while the DC voltage supplies to the armature through four Diodes.
In This ckt the motor is controlled through armature voltage, while the field voltage is at a constant value.
In the ckt the SCR 1 & SCR 4 are triggered at same time in first cycle, while in next half cycle SCR 2 & SCR 3 are conduct.
The motor armature receives a continuous or Discontinuous voltage depends on the firing angle of the SCR, Power factor.
In Discontinuous armature current , SCR 1 & SCR 4 are fire at angle α due to which the current flow path is form α to β , as shown in the Fig:
The motor armature receives voltages form α to β, while form β to π + α the motor can’t receive current.
Through this way the speed of a DC motor is controlled.
Tuesday, August 12, 2014
Remote controlled appliance switch circuit
Here is a versatile remote controlled appliance switch that can ON or OFF any appliance connected to it using a TV remote.
IR remote sensor IC TSOP 1738 is used for receiving the signal. Normally when no signal is falling on IC3 the output of it will be high.This makes Q1 OFF.When a signal of 38 KHz from the TV remote falls on the IC3 its output goes low.This makes Q1 conduct and a negative pulse is obtained at pin 2 of IC 1 NE 555.Due to this IC1 wired as a monostable multivibrator produces a 4 Sec long high signal at its out put.This high out put is the clock for IC 2 which is wired as a Flipflop and of , its two outputs pin 3
goes low and pin 2 goes high.The high output at pin 2 is amplified to drive the relay .For the next signal the outputs of IC2 toggles state. Result, we get a relay toggling on each press on the remote.Any appliance connected to this schema can be switched ON or OFF.
Notes .
* Before wiring the schema make sure that the carrier frequency of the
TV remote you have is 38 kHz.For that wire the sensor part only ,point your
remote to the TSOP1738 and press any switch.If out put of TSOP1738 goes
low then OK, your remote is of 38Khz type.Nothing to worry almost all TV
remote are of this type.
* You can use any switch of the remote because for any switch the code only changes,
the carrier frequency remains same.We need this carrier frequency only.
* Assemble the schema on a good quality PCB or common board.
* The appliance can be connected through NO or NC and C contacts of the relay .
* Use a regulated 6V power supply for the schema.
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