How to extend the touch sensitive press of lithium battery life

　　Author ：Iflowpower – Portable Power Station Supplier

Some type of photovoltrium mouse uses two AA alkaline batteries. It has no power switch. When not in use, it automatically switches the switch of the light source at a low duty cycle to reduce power consumption.

However, this function will still run out of battery energy, so that the mouse cannot be used. The problem with the problem is to add a battery switch that automatically disconnects the battery after a pre-press time. This approach does not disassemble or other types of modifications.

This design example describes two unique implementation methods that use a touch sensitive on-time switch that can add a lot of equipment that use the battery, and may not intend to uninterrunction. Figure 1 The circuit represents the simulation implementation of the switch. Figure 2 and Figure 3 are digital implementation.

This concept is placed in a 30 mIl double-sided PCB (printed circuit board) strip between the negative electrode of the battery and the battery holder (A) in the figure (A) in the figure. Q3 is a low threshold MOS transistor that is connected to both sides of the slat, as a switching element (Fig. 1).

C1 is a 0603x7R ceramic chip capacitor, R1 is a 0603 chip resistance. Install Q3 and all related components in the upper edge close to A. B is a thin narrow copper strip, which is connected to the positive electrode of the second battery.

Connect it to the circuit with a thin and flexible line. The touch point C and D are made of a self-adhesive copper strip, and the copper is fitted outside the battery chamber. Soft thin lines connect C and D to the circuit.

Q1, Q2 and C1 constitute a single stable trigger. When the switch is closed, the C1 is not charged, Q1 and Q2 are closed. When simultaneously touch C and D with a naked finger, the current flows through the threshold level of the C1 to Q2.

Q2 and Q1 are all conducted, C1 via Q1 and your conductive finger discharge. Thus, the voltage level of the Q2 gate is close to the battery voltage. After removing the finger, the leakage current of the Q2 internal gate protection (the Zener diode in the figure) appears in the Q2 gate, the voltage slowly reduces, until the threshold level of about 1.

3 V. Q2 ends turn, and makes a recovery action with Q1, quickly shut down Q3. The switch remains closed until C and D are touched again.

E is an optional contact, which is similar to C and D. If you touch E and D, the switch is turned off. C1 uses 0.

01? F, the delay obtained is about 1 hour. Because the gate leak is in the number of piya, you must use the flux detergent to clean the circuit, then cover it with a dropwax or epoxy resin. In some cases, you may want to adjust the timing of the switch.

The circuit in Figure 2 supplies this option. It uses a microcontroller for SOT-23 package. Code Listing 1 contains a touch activated press.

The same as the same as in Fig. 1. When the switch is turned off, the PIC10F200T microcontroller is in sleep mode, and there is almost no power consumption.

When you touch the contacts C and D at the same time, the PIN1 of IC1 is high, the microcontroller begins, and the Pin1 is kept high. After 0.5, the buzzer issued a short sound.

The buzzer then issues two, three and four short sounds at 0.5 s intervals. When you hear any kind of sound, release the contacts C and D immediately, you can set the switch to 30 seconds, 30 minutes, 4 hours, and 8 hours.

Working time can be arbitrarily selected, you can modify the code in the code list 1 to accommodate your own application. Jumper switch J1 is optional. If J1 is open, touch C and D can close it.

Turn J1 to close this option and turn off only at the end of the preset time. Since this is analog implementation, all components other than the buzzer can be mounted on the edge of a. The buzzer is a small piezoelectric component, the resonant frequency is 4kHz, which is easy to put in the battery case.

In some cases, it is impossible to contact the negative contact of the battery holder. The circuit in Figure 3 can solve this problem. It is basically consistent with the circuit in Fig.

2, but the A and the positive electrode are connected to the negative electrode of B. The P-channel MOS tube is used as a switch, and the procedure of the microcontroller must be modified, and the low level of the driving Q1 is supplied. Note in Listing 1 describes the line number where the option is located for Figure 2 or Figure 3.

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