Privacy Hydrogel Screen Protector
The Privacy Screen Protector can display a black screen directly in front of the screen at an angle greater than 30° to effectively block the sight of people next to it, while achieving a perfect balance between black screen privacy and daytime clarity.
The Screen Protector can protect the edges and gaps of the display so that it can extend to the entire screen surface, thereby achieving maximum coverage without any exposed space.
The Self-Healing Screen Protector can provide the best protection for your phone from drops, bumps, scratches and normal wear and tear. Using an oleophobic waterproof coating can prevent sweat and grease from remaining on your fingerprints, keeping you simple all day long.
The 0.14mm thick Ultra-Thin Protective Film has a "real touch" feel and ensures fast response performance.
If you want to know more about Privacy Screen Protector products, please click the product details to view the parameters, models, pictures, prices and other information about Privacy Screen Protector.
Whether you are a group or an individual, we will try our best to provide you with accurate and comprehensive information about the Privacy Screen Protector!
Anti-peep Screen Protector, Privacy Screen Protector, Anti-spy Screen Protector, Privacy Protective Film, Privacy Hydrogel Film,Anti-peeping Screen Protector Shenzhen Jianjiantong Technology Co., Ltd. , https://www.jjthydrogelmachine.com
Circuit Operation Principle The electronic stethoscope circuit consists of a microphone preamplifier that controls the vertical control and power amplifier, as shown in Figure 9-137. 
The preamplifier circuit is composed of transistors V1, V2 and capacitors C1, C2, resistors R1, R2.
RP is the volume potentiometer.
The selection switch S and the capacitors C4-C6 constitute a tone control circuit.
The power amplifying circuit is composed of an integrated circuit IC and capacitors C3, C7-C9.
The microphone BM is mounted on the probe of the stethoscope, which converts the sound signals of the human heart, lungs, pulse and the like into electrical signals, and then is coupled to the base of V1 through Cl, and is controlled by Vl, V2 preamplification and volume and tone control. The 3-pin input of the power amplifier IC lC. The amplified audio signal from the IC is output from its 5 pin, coupled to the headphone jack XS via C8, and finally the amplified sound is restored by the external earphone.
Component selection
Rl selects 1/4W metal film resistor for use; R2 selects 1/2W metal film resistor for use.
Cl, C2, C4-C6 and C9 use monolithic capacitors or polyester capacitors; C3, C7 and C8 are all made of aluminum electrolytic capacitors with a withstand voltage of 16V.
Vl and V2 select S9013 or 3DG6 type silicon NPN transistor.
IC selects LM386 type power amplifier integrated circuit.
The BM uses a high sensitivity electret microphone or a piezoelectric ceramic sheet.