Gas flameout alarm circuit with automatic ignition

Gas flameout alarm that can automatically ignite. This device is in the detection state after igniting the gas. Once the gas stove goes out by itself, it can automatically ignite continuously and sound a music alarm. 　　

working principle 　

The circuit principle is shown in Figure 1. Switch S is linked to 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 emit music. At the same time, transformer T1 boosts and outputs a pulse voltage with a peak value of 120Vpp, which is charged through C1 through R5 and charged through C2 through VD1. When C1 reaches a certain voltage, the trigger tube VD2 is turned on and the thyristor is turned on, causing the charged C2 to discharge through the T2 primary and the thyristor. As a result, a high voltage of 5-10kV is induced in the secondary of T2, which is discharged from the tip of the discharge needle, igniting the gas. After the gas is ignited, the resistance of the photoresistor decreases when exposed to the flame, causing VT1 to cut off. The music stops after the music is played, and the discharge also stops. It can be seen from the circuit analysis that when the gas flame is extinguished again, the circuit will automatically ignite continuously and sound a music alarm. The component selection and production component list is shown in the table below. No. Name Model Quantity R1 Resistor 1K 1 R2 Photoresistor MGL-45 1 R3 Resistor 3K 1 R4 Resistor 150K 1 R5 Resistor 4M 1 C1 Metalized low dielectric capacitor 0.1u/160V 1 C2 Metalized low dielectric capacitor 0.47/160V 1 VD1 Rectifier Diode IN4004 1 VD2 Trigger diode DB－3 1 VT1 Transistor 3DG6 β≥80 1 VT2 Transistor 3DG12 β≥100 1 VS Triac 3CTS1 1 YD Piezoelectric ceramic chip plus sound cavity 1 IC Music integrated circuit KD－128 or The other 1 S travel switches of about 10 seconds are shown in the text below the table 1. This device consumes very little. Generally, two AA batteries can be used for more than half a year. The switch S can be installed together with the gas stove switch using an appropriate travel switch. The music integrated circuit can be any type that plays music for about 10 seconds. The photoresistor is MGL-45 type. It is fixed in a round tube during production, installed 10cm away from the flame and aligned with the flame. T1 uses the output transformer of a semiconductor radio and is used in reverse. 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 3CTS1 with a small trigger current and a withstand voltage of 400V. T2 can be modified with a 12-inch TV line output, remove the original low-voltage part, use Φ=0.35mm high-strength enameled wire to wind 15 turns around the original frame; use the original high-voltage package on the secondary side and remove the rectifier tube. The discharge needles are made from bicycle spokes, and one end of the spokes is sharpened. The distance between the two discharge needles is preferably 5mm. Link the switch S lead to the gas switch, and adjust R1 so that VT1 is cut off and turned on when there is a flame or not. The igniter is installed in the free position of the gas stove, and the discharge needle is aligned with the gas nozzle.