Find a delay design circuit, the simplest delay circuit

Transistor delay circuitry

There are many types of electronic delay circuits, and the simplest one is the transistor delay circuit, as shown in the figure below. The transistors in the picture are two 9014s, which form a composite tube to increase the magnification.

Switches, relays, transistors, resistors, capacitors, small delay switching circuits are shown in Figure D1--D1, SCR constitutes the main circuit of the switch, BG1, BG2 and other control loops of the switch.

Normally, BG1 and BG2 are in the cut-off state, the SCR is blocked, and the lamp H is not on. At this time, the 220V AC is rectified by D1-D4, R3 and DW to make the LED glow, which is used as a night indication of the switch position. At this time, the current flowing through h is only about 2mA, which is not enough to make the lamp h glow.

When you need to turn on the light, you can only touch the electrode m with your finger, because the human body leakage current is injected into the base of BG2 through R5 and R6, and BG2 is quickly turned on. The collector of BG2 is low, and BG1 is also turned on, so there is a trigger current injected into the control electrode of the SCR through BG1 to turn on the SCR, and the lamp H is energized and emitted.

At the moment when BG2 is turned on, C1 is connected in parallel at both ends of the DW through the C-E poles of BG2, so it is quickly charged with a voltage of about 12V. After the lamp is lit, the human hand leaves M, and although BG2 returns to the cut-off state, the charge stored in C1 is discharged by the junction discharge from R1 to BG1, so that BG1 remains on, so the lamp continues to shine.

When the C1 charge is basically discharged, BG1 returns to the cut-off state, the SCR loses the trigger current, and when the alternating current crosses zero, the SCR is turned off and the light is turned off.

The switching delay time is mainly determined by the values of resistors R1, R2 and capacitance C1, and a set of experimental data is provided below for your reference. To further increase the delay time, increase the C1 capacity. In addition to the main factors mentioned above, the magnification of BG1 and the triggering sensitivity of the SCR also have an impact on the delay time.

Circuit diagram: Follow the above circuit diagram to operate soldering to correctly design the desired effect.

Circuit Principle Analysis:

Normally, BG1 and BG2 are in the cut-off state, the SCR is blocked, and the lamp H is not on. At this time, the 220V AC is rectified by D1-D4, R3 and DW to make the LED glow, which is used as a night indication of the switch position. At this time, the current flowing through h is only about 2mA, which is not enough to make the lamp h glow.

When you need to turn on the light, you can only touch the electrode M with your finger, because the human body leakage current is injected into the base of BG2 through R5 and R6.

BG2 is rapidly turned on. The collector of BG2 is low, and BG1 is also turned on, so there is a trigger current injected into the control electrode of the SCR through BG1 to turn on the SCR, and the lamp H is energized and emitted. At the moment when BG2 is turned on, C1 is connected in parallel at both ends of the DW through the C-E poles of BG2, so it is quickly charged with a voltage of about 12V.

After the lamp is lit, the human hand leaves M, and although BG2 returns to the cut-off state, the charge stored in C1 is discharged by the junction discharge from R1 to BG1, so that BG1 remains on, so the lamp continues to shine. When the C1 charge is basically discharged, BG1 returns to the cut-off state, the SCR loses the trigger current, and when the alternating current crosses zero, the SCR is turned off and the light is turned off.

The switching delay time is mainly determined by the values of resistors R1, R2 and capacitance C1, and a set of experimental data is provided below for your reference. To further increase the delay time, increase the C1 capacity. In addition to the main factors mentioned above, the magnification of BG1 and the triggering sensitivity of the SCR also have an impact on the delay time.

The simplest delay circuit.

Your request is really simple

The two ends of the buzzer are solved by combining one capacitor, the larger the capacitor, the longer the delay.

Hope, thank you.

The high requirements are made with 8-foot single-chip microcomputers, and the low requirements are made with 555. Which one do you choose.

<> note: Increasing C1 can extend the power-on time, and R3 is the relay.

Principle: 1: After powering on, the base level of Q1 is high, and the charging level of C1 slowly becomes low.

2: When C1 is fully charged, then Q1 is cut-off, then Q2 base level is high, then Q2 is on, and the R3 relay is closed.

Others: 8050 can be selected for Q1.

A delay circuit is an electrical circuit.

The name of the manifestation form, the circuit pattern is called the monostable circuit.

There are many and common delay circuits centered on 555, and the circuit structure is short-answered, with few peripheral components and stable operation.

The capacitor delay is the RC delay, which is completed by using the charge and discharge of the capacitor to adjust the RC time constant, and generally needs to cooperate with another trigger circuit to achieve delay control, in fact, the 555 delay circuit is the RC charge and discharge used.

Relay time delay In the field of strong electricity, there are time relays, etc., which use the electromagnetic principle. In the field of weak current, solid-state relays are generally the mainstay, but it is also only a control device.

In addition, in digital circuits, the use of ** and counter can also be made into a fairly accurate delay circuit.

If the cost is considered, RC delay can be used directly, and a triode is added to form a delay control circuit.

If you think about performance but it's not very high, you can use the 555.

If it is in high-precision occasions, such as digital sampling, etc., then a digital delay circuit should be used.

Speaking of delay circuits, for non-professionals is probably the most familiar is the relay bar amusement, this kind of indispensable actuator in a variety of automatic control circuits can effectively control current control, today in response to the call of netizens to give a brief introduction to the knowledge of various types of delay circuits, I hope to broaden some knowledge for everyone in the delay circuit, want to know what the delay circuit is, this is to see!

Relays. The full name of the relay is called "electromagnetic relay", which is a kind of relay that we commonly use in our daily life, and now the hot-selling 4089 relay on the market is a kind of relay with small size and large effect, and the common ultra-small relay has different specifications such as 3V and 6V, but when it is engaged, the current passing through the coil is about 59 milliamperes, which is very consistent.

Fabrication of delay switching circuits.

It is simple because we can make it according to the circuit diagram drawn in advance, and it is complicated because it is complicated because the production of the delay switching circuit involves a series of welding procedures, and the early procurement of the delay circuit is also a huge project.

Commissioning and application of delay switches.

First of all, we need to monitor the status of all solder joints on the printing plate, if there is a virtual soldering or false soldering, it should be treated in time, for the adjacent solder joints, the space around them should not leave dust and other impurities, once the dust accumulates too much, it is likely to cause a short circuit between the solder joints. After the above checks, we adjust the R active point in the adjustable resistor to the middle position, and turn on the 6V series power supply. At this time, press the button switch, if you hear a "da" sound, it means that the relay has been engaged, and soon after you hear a "da" sound again, it means that the relay has been released, and the relay is working completely normally, if we want to change the delay time during the use of the relay, we can adjust the r value, the larger the value, the longer the delay time, if you want the delay time in actual operation to be greater than the maximum delay time of the total circuit, we have to use a larger capacity electrolytic capacitor.

After talking so much, I don't know if you have a comprehensive understanding of the delay circuit in the electrolyzer, the delay circuit as one of the most widely used electronic circuits, in daily life we need to protect it well, in case of unexpected situations such as the delay circuit emitting fire, we should close it in time.

You can get it for free

Take a look at the picture

A time-delay circuit consisting of a thyristor.

Using the MCU to make a simple circuit, the timing time can be controlled by the button, plus the relay.

The time relay can realize the delay function, why can't it meet your requirements, can you say it in more detail?