description:
This is a mobile phone shielding circuit that can be used as a mobile phone charger. This simple circuit work is guaranteed to your phone, accidental use or theft. When someone tries to take the phone away, it is able to produce a loud scream. The new feature also acts as a mobile charger circuit.
This circuit consists of rectifier diodes D1 and D2 of step-down transformer X1 and filter capacitor C1. Regulator IC 7812 (IC1), along with noise filter capacitors C2 and C3, provides regulated power.
The cell phone masking circuit uses two NE555 timer ICs: as a very simple multivibrator (IC2), it is a second monostable multivibrator (IC3). Multivibrator timing resistors R1 and R2, but no timing capacitors because it works with stray capacitance. Its pins 6 and 2 are directly added to the protective shield to build a 10 cm x 10 CM copper clad laminate.
The inherent stray capacitance of the circuit is sufficient to provide an output frequency of approximately 25 kHz with R1 and R2. This arrangement provides better sensitivity and circuitry allowing for manual capacitive effects. The output pulse immediately assigned to the oscillator triggers pin 2 of the monostable multivibrator. The monostable uses the low capacitance C6, the resistor R3 and the timing of the preset VR1.
Using the preset/fine-tuned VR1, it is slightly higher than the multivibrator, and the output frequency of the monostable multivibrator changes. This makes the circuit standby, as long as there is no hand capacitance present. Therefore, in standby mode, the unsteady output will be low. This tends to make the trigger monostable low and the output high.
The warning indicator buzzer and LED1 are added and they come to be active only when the output of the monostable multivibrator sinks current. In standby mode, LED1 continues to "off" and the buzzer is silent. Since someone attempted to remove the phone from the defending shield, his hand approached the shield and shield, introducing the hand capacitance in the circuit contact. Because of this, the unsteady frequency changes, which causes the monoflop pin to go low and its output to oscillate. This will produce a chirping sound from the buzzer and also cause LED1 to flash.
It can even be used as a circuit for a mobile phone charger. It provides 180 mA to charge the phone through the regulator IC 7806 (IC4) and resistor R5 6V output. Diode D3 defends the output polarity reversal.
Generally, the circuit on the PCB can be wired. Included in an appropriate case, it provides the output leads of the charger. An umbrella is produced using a 10 cm x 10 cm copper clad plate or aluminum plate. Hang it up on a circuit that works on a 15 cm plastic line. The information for all capacitors should be short-term.
Fine-tune the VR1's small plastic screwdriver until the final buzzer stops sounding by small. Send the shield near the hand and fine-tune the VR1 until the buzzer sounds. The test and the wrong method set it to the highest level of sensitivity, for the hand close to the shield, the buzzer began to chirpring the LED flashing. As an alternative to applying for a shielded copper bag, metal phone holders can use it as a shield.
Shaanxi Xinlong Metal Electro-mechanical Co., Ltd. , https://www.cnxlalloys.com