What is the difference and connection between point timer and spark timer?

A, the difference between electromagnetic dot timer and electric spark dot timer:

1. Use different power supplies.

The working voltage of the electromagnetic dot timer is generally 4-6V, so it is necessary to connect the dot timer with the AC file of the student power supply.

When using EDM timer, the power plug is directly inserted into AC 220V socket.

2, the working principle is different

After the coil of the electromagnetic dot timer is energized, the coil generates a magnetic field, and the vibrating plate is magnetized and moves up or down under the action of the magnetic field of the permanent magnet.

Spark point timer is a kind of timing instrument which uses spark discharge to make toner dots and display dots on paper tape. After turning on the power supply, press the pulse output switch, and the pulse current sent by the timer reaches the disk shaft connected to the negative electrode through the discharge needle connected to the positive electrode and the toner disk, generating spark discharge and punching a series of dots on the paper tape.

3, the error is different

When the electromagnetic dot timer ticks, the vibration impacts and rubs the paper tape, which not only affects the normal movement of the paper tape, but also affects the movement of the vibrating needle, so the error is large.

The EDM timer uses high voltage pulse discharge, and the discharge needle does not contact with the paper tape, which does not interfere with the movement of the paper tape, and the error is very small.

4, instrument adjustment

When using the electromagnetic dot timer, the carbon paper must be changed to a new position after each paper tape is punched, otherwise the dot will be unclear.

EDM timer has no vibrating needle, so there will be no short horizontal line, but the position of toner tray needs to be changed frequently.

Second, the connection between electromagnetic dot timer and electric spark dot timer:

Spark point timer is a kind of timing instrument which uses spark discharge to make toner dots and display dots on paper tape. And discharges once every AC cycle, so the time interval between the dots of the electric spark dot timer is equal to the AC cycle.

No matter what kind of ticking timer is used, if the paper tape is connected with a moving object, that is, the object drives the paper tape to move together, the distance between points on the paper tape indicates the displacement of the object in the corresponding time interval, and the "space-time" distribution information of the moving object is recorded on the paper tape.

When the power frequency is 50 Hz, the clock strikes every 0.02 s, so the data acquisition method and data analysis method of the two timers are the same.

Extended data

1. Fixation of electromagnetic dot timer

The electromagnetic dot timer should be fixed first when it is used. There are two grooves on its base, which can be fixed on the edge of the experimental table or one end of the inclined plane with a table clip. Pay attention to make the center line of the paper tape consistent with the movement direction of the object or with the direction of the crown block groove at the other end of the inclined plane.

If the dot timer is used alone, it can also be fixed on the pillar of the iron bracket with a vise.

2. Adjustment of electromagnetic dot timer

Connect the dot timer to a 50 Hz 6 V sinusoidal AC power supply (J 1202 or J 1202- 1 student power supply, and the dot timer can work normally in the range of 7- 1 1 V), let the dot timer start working, and observe whether the vibration of the vibrating plate is uniform.

If the vibration is uneven, adjust the adjusting nut of the vibrating plate until the dots are uniform and strong, with clear sound and no tailing. Indicates that the point timer has been working normally. Then turn off the power.

Install the carbon paper sheet on the dot timer, move the rotating shaft of the carbon paper, and press the carbon paper under the paper press frame. The paper tape passes through the paper tape limit hole, the carbon paper and the other limit hole.

Turn on the power supply, make the dot needle work, adjust the height of the dot needle, so as to mark dots on the paper and minimize the contact time between the dot needle and the dot paper tape. The electromagnetic dot timer uses alternating current, and the working voltage is below 6v.

References:

Baidu encyclopedia-electromagnetic dot timer

Baidu encyclopedia-EDM timer