Automatic hand dryer one

Circuit Working Principle
The infrared automatic hand dryer circuit consists of a power supply circuit, an infrared transmitter circuit, an infrared receiver amplifier circuit, a delay circuit and a hot air blower control circuit, as shown in Figure 9-124.

The power circuit is composed of power switch S, step-down capacitor Cl, resistors Rl, R2, Zener diode VS, rectifier diode VDl, filter capacitor C2 and power indicator light-emitting diode VLl.
The infrared emission circuit is composed of NOT gates Dl and D2, resistors R3-R6, capacitor C3, transistor Vl and infrared light-emitting diode VL2 inside the NOT gate integrated circuit IC (D1-D5).
The infrared receiving amplifier circuit is composed of infrared photodiode VD2, resistors R7-Rl2, capacitors C4-C6 and transistors V2 and V3.
The delay circuit is composed of NOT gates D3-D5, diode VD3, resistor R14 and capacitor C7 inside the IC.
The hot air blower control circuit is composed of resistors Rl5, RI6, diode VD4, transistor V4, relay K, fan motor M and electric heating wire EH.
Turn on the power switch S. After the AC 220V voltage is stepped down by Cl, stabilized by VS, rectified by VDl and filtered by C2, a DC voltage of about 12V is generated, which is used as the working power supply for the relevant circuits of the whole machine. At the same time, after the current limiting step-down by R2 Light up VLl.
After the infrared emission circuit is powered on, the oscillator composed of NOT gates Dl, D2 and R3, R4, C3 oscillates and generates a modulated pulse signal, causing V1 to conduct intermittently and driving VL2 to emit modulated infrared light.
Normally, VD2 cannot receive the modulated infrared light emitted by VL2, the positive end of C7 is low level, and the NOT gate D5 outputs high level, causing V4 to cut off, K is in the release state, and the hot air blower (composed of the fan motor M and the electric heating wire EH composition) does not work.
When someone puts their hand on the air outlet below the hand dryer, the infrared light emitted by V is reflected by the person's hand and received by VD2. VD2 converts the infrared light signal into a corresponding electrical signal, which is then amplified and non-contacted by V2 and V3. After the shaping processing of gates D3 and D4, C7 is charged through VD3. When the voltage at both ends of C7 is charged to a certain value, the NOT gate D5 outputs a low level, causing V4 to saturate and conduct, VL3 lights up, and K is powered on. When the open contacts are connected, M and EH are energized to work, generating hot air to blow to the human hands to dry them.
When the human hand leaves the air outlet, VD2 cannot receive the reflected infrared light and is in a high-impedance state. The signal at the output end of the NOT gate D4 disappears. C7 is discharged by R14, so that the NOT gate D5 still outputs a low level. V4, K and M, EH all remain working. When the discharge of C7 ends (about 3s), D5 outputs a high level, causing V4 to cut off, K is released, its normally open contact is disconnected, and M and EH stop working.
Component selection
Rl-R16 uses 1/4W metal film resistor or carbon film resistor.
Cl uses a CBB capacitor with a voltage rating of 450V; C2 uses an aluminum electrolytic capacitor with a voltage rating of 25V; C3, C5 and C6 all use high-frequency ceramic capacitors; C4 and C7 all use aluminum electrolytic capacitors with a voltage rating of 16V. .
VS uses lW, l2V silicon zener diodes.
VLl and VL3 both use φ5mm ordinary light-emitting diodes; VL2 uses HG301 infrared light-emitting diodes.
VDl and VD4 both use 1N4007 silicon rectifier diodes; VD2 uses RPM-301B infrared photodiodes; VD3 uses 1N4148 silicon switching diodes.
Vl uses S9013 silicon rectifier diodes; V2 and V3 both use S9014 silicon NPN transistors; V4 uses S8050 silicon NPN transistors.
IC selects CD4069 or CC4069, MCl4069 six-NOT gate integrated circuit.
K selects JRX-l3F type l2V DC relay (use its two sets of normally open contacts in parallel).
EH uses 500-1000W electric furnace wire.
M chooses 15-25W AC fan motor.
S selects a 10A, 250V power switch.