الجهاز المرسل لإشارات التحكم عند بعد بالأشعة تحت الحمراء .كتاب التلفزيون لملون ولعادي

19-19 The infrared remote control transmitter:

Figure (19-34) shows the circuit of the device. When one of the pistons is pressed, infrared waves are generated, modulated by the carrier with a frequency of 42 kHz, and in one of the 16 patterns of pulses, identical to the number of control functions or compressors.

Circuit working principle:

When one of the pistons is pressed, the circuit generates a series of pulses from the integrated circuit encoder (IC1001), and is applied to the input of the encoder, so this encoder generates a distinct pulse pattern at the output for each of the compressors, and applies at the same time only one pulse pattern On rectifier transistor base (Q1001), integrated circuit (IC1001) fed by DC voltage (15) rectifier transistor collector (Q1001) and gate transistor base (Q1003)

Infrared modulation:

When the gate transistor (Q1003) receives a constant DC base voltage from the encoder (IC1001), it drives the oscillator (Q1002) generating the frequency (42 kHz), however, when any button is pressed, the pulse pattern is one and unique for each button. It feeds the gate base of the transistor (Q1003) and the effect of the pulse model is to turn (Q1003) off and on according to the pulse model, and then (Q1003) modifies the oscillator (42 kHz) which is the transistor (Q1002) in accordance with the same pulse model, and produces modified pulses Loaded on a wave (42) kHz. This modulated carrier is combined into a tuned modulated transformer (T1001) with an infrared catalyst (Q1004).

Infrared Output: The modulated signal (42kHz) via an infrared driver or driver (Q1004) causes the three LEDs to emit modulated infrared waves in the pulse pattern that characterizes each function: In addition to that The modified 42kHz output from the T1001 does a binary ​ and the function indicator (LED) on the front of the transmitter lights up. Its illumination indicates that one of the function compressors has been pressed. And not lighting it could indicate the need to change the battery due to its weak current. Note: All control functions operate on a modulated carrier with a typical pulse frequency (42 kHz). An exception is the volume up and down function. Where the pulses of the same form only start the function and then continue by themselves to work within the maximum and minimum limits).

19 - 20 remote control receiver:

Figure (35-19) shows the TV receiver control circuit. The modified infrared wave coming from the transmitter picks up the signal by an infrared sensor diode (D1101) and this signal is first amplified by the transistor (Q1103) and then connected to the integrated circuit (IC1101) - and in the integrated circuit the signal is also amplified and then passes through terminal 7 with DC connection to the sensitive transistor amplifier (Q1101). Then the signal passes through the transformer (T1101) and the detector diode (D1102) via pin 6 and to the signal modulator in the integrated circuit (IC1101) in which only the positive half of the amplified signal enters - and this pulse of a specific pattern is delivered to a microcomputer circuit called (Compu-Matic) which In turn, it produces the appropriate output to implement the control commands, as shown in the figure

Operation (Power-On):

To turn on the device, he presses the ON - OFF button - thus, a positive voltage reaches terminal (2) of the (Compu-Matic) microcomputer circuit - and this voltage passes into the link R2.3 to feed the base of the catalyst transistor (ON-OFF) which is Q1102 (according to the figure) . The transistor becomes in the conducting state and makes the LED light up in the optical link E1101 and the optical link isolates the microcomputer from the AC mains supply line - when the LED lights up the LDR resistance decreases the resistance related to the light - and the LDR element's low resistance now applies an AC voltage of AC 110 or 220 V to the gate Triac (D1104). The triac is a bi-directional AC semiconductor switch that controls the thyristor gate and provides full wave AC control. When the triac is connected to both the positive and negative halves of the AC voltage, it works as an AC circuit breaker.

OFF:

To turn off the TV set, the (ON-OFF) button must be pressed again in the control device (transmitter), thus removing the positive voltage on the base of the on-off catalyst transistor which is (Q1102), so the optical link lamp (Optic-) turns off Coupler) - so the LDR becomes high-resistance - and the triac stops connecting: this is what leads to cutting off the AC voltage from feeding the TV.