Simple self-controlled ignition gas flameout alarm circuit

The device is in the detection state after igniting the gas, and once the gas stove is self-extinguishing, it can automatically ignite continuously and issue a music alarm.
The circuit principle is shown in Figure 1. The switch S is linked with the gas stove switch. When the gas is turned on, the switch S is closed. If the gas is not ignited at this time, the photoresistor R2 is in a high resistance state, and the transistor VT1 is turned on, triggering the music integrated circuit to work and emitting music. At the same time, the transformer T1 boosts the output to a pulse voltage of 120Vpp, which is charged by C1 via R5 and charged by C2 via VD1. When C1 reaches a certain voltage, the trigger tube VD2 is turned on, and the thyristor is turned on, so that the charged C2 passes through the T2 primary and the thyristor (the thyristor, which is an abbreviation of the thyristor rectifying element, is a type having three A four-layer high-power semiconductor device with a PN junction, also known as a thyristor, is one of the more commonly used semiconductor devices because of its small size, relatively simple structure, and strong function. The device is widely used in various electronic devices. And electronic products, used for controllable rectification, inverter, frequency conversion, voltage regulation, non-contact switch, etc. Dimming lights, speed control fans, air conditioners, televisions, refrigerators, washing machines, cameras in household appliances Controllable silicon devices are widely used in combination sound, sound and light circuits, timing controllers, toy devices, radio remote controls, video cameras, and industrial controls. As a result, a high voltage of 5-10 kV is induced in the secondary of T2, which is discharged by the tip of the discharge needle to ignite the gas. After the gas is ignited, the resistance of the photoresistor is lowered by the flame, causing VT1 to be cut off, the music stops after the sound is finished, and the discharge stops. It can be seen from the circuit analysis that when the gas flame is extinguished again, the circuit will automatically ignite continuously and emit a music alarm.
The list of components is shown in the table below:

Numbering	name	model	Quantity
R1	resistance	1K	1
R2	Photoresistance	MGL-45	1
R3	resistance	3K	1
R4	resistance	150K	1
R5	resistance	4M	1
C1	Metallized low dielectric capacitor	0.1u/160V	1
C2	Metallized low dielectric capacitor	0.47/160V	1
VD1	rectifier diode	IN4004	1
VD2	Trigger diode	DB-3	1
VT1	Crystal triode	3DG6 β≥80	1
VT2	Crystal triode	3DG12 β≥100	1
VS	Two-way thyristor	3CTS1	1
YD	Piezoelectric ceramic sheet	Auxiliary cavity	1
IC	Music integrated circuit	KD-128 or other 10 seconds or so	1
S	Limit switch	See the text below the table	1

The device consumes a small amount of electrodes, and generally two sections of the 5th battery can be used for more than half a year. The switch S can be mounted in one piece with a gas switch by means of a suitable travel switch. The music integrated circuit can be played in any of the following 10 seconds. The photoresistor is made of MGL-45. It is fixed in a round tube when it is manufactured. It is installed at a distance of 10cm from the flame and aligned with the flame. The T1 uses the output transformer of the semiconductor radio and is used upside down. VD1 uses a rectifier diode with a withstand voltage greater than 200V. VD2 is the trigger tube. The values ​​of C1 and C2 determine the discharge intensity and speed. The thyristor uses a small trigger current of 3CTS1 and a withstand voltage of 400V. T2 can be modified by 12-inch TV line output, remove the original low-voltage part, and use the high-strength enameled wire with Φ=0.35mm to wind around the original frame by 15 turns; the secondary can remove the rectifier tube with the original high-voltage package. The discharge needle is made by bicycle strip, and the end of the strip is sharpened, and the discharge needle is preferably 5 mm. The switch S is led out to be linked with the gas switch, and R1 is adjusted so that VT1 is turned off and on when there is no flame. The igniter is installed in the idle position of the gas stove, and the discharge is directed to the quasi-gas vent.