Inductive pointer watch battery tester circuit diagram

Test probe P100-M3

Test - lowercase jpg

Kaixin micro test

The watch battery tester described in this paper uses the non-contact method to sense the driving pulse of the second hand of the electronic watch. It is convenient and quick to judge whether the battery and the driving circuit in the watch are normal, and the sound is accompanied by the sound of the watch. The light display, together with a moving coil meter, can measure the voltage of various low-voltage batteries within 3V.

The tester can be used as a professional instrument for the maintenance of timepieces.

The circuit principle is shown in the figure on the right. The working principle is as follows: U1C forms an oscillation circuit with a frequency of 2 kHz and directly drives the piezoelectric ceramic horn B. V2, L, and C form a high-frequency oscillation circuit, which is amplified by V1 and then enters U1B for shaping. Usually, the high-frequency signal is filtered by C11 to become a constant DC level. The 1st leg of U1A is set to a high level (H) by 1t6 and R2. When the circuit is in a stable state, the 2 pin is high (H), so 3 The pin is low (L). At this time, the U1D one-shot circuit of the latter stage is clamped, VD3 is turned off, and the signal circuit does not work.

When the electronic watch is close to the tester and senses the L terminal, the driving pulse signal in the second hand coil causes the oscillation frequency of V2 to be modulated to the same low speed frequency as the pulse signal, after V1 amplification and U1B shaping. Pull the U1A pin 1 low (L) and the U1A pin 3 to the high (H). Since the level of C2 can not be abrupt, the U1D(11) pin goes low (L), VDI is illuminated, and the U1C signal circuit starts to work. After about 0.5s, C2 is charged through the R1 loop. Once the charging is completed, U1D The (12) and (13) feet start to go low (L), the U1D's (11) pin flips high (H), VD1 dims, and the U1C semaphore circuit is turned off by the diode VD3.

The installation and debugging of this circuit is very simple. U1 is a four-two input CMOS Schmitt trigger CD4093, which is powered by DC9V laminated battery. During power-on, B1 will have a short-term signal due to the steady state establishment process. When the base of V2 is touched with a finger, the monostable circuit operation of U1 is continuously triggered. A moving coil head that indicates the battery capacity. The type of battery under test can be selected by a multi-knife slide switch. The overall shape of the instrument is: 160mm × 128mm x 41mm, and the gross weight is about 320g.

The ordinary pointer type electronic watch generates a drive pulse every second, and the ultra-thin electronic watch without the second hand function generates a drive pulse every 6 to 10 seconds. The strength of the driving pulse signal can be judged by the distance of the distance L of the electronic watch. The instrument can be used to instantly determine whether the drive circuit is faulty or the mechanical circuit is faulty. In addition to sensing ordinary electronic watches, the circuit can also sense the working state of quartz clocks, BP machines, mobile phones, electric toys and other appliances.