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Piezoelectric earphones also known as crystal earphones are the most sensitive earphones. In fact they are at least 10 times more sensitive than very sensitive magnetic earphones, dynamic earphones, and electrostatic earphones. Sensitive earphones have a very high impedance, which is measured in ohms.
Which means no output cap is required for stereo and if just mono earphone, any stereo amp with differential output can be capless on output as well.If you read the datasheet and look at the amplifier schematic for the LM4911 stereo amplifier you will see that it has three amplifiers, not just two...
You do not understand that a high current from an amplifier with high output power is needed to produce enough electromagnetic energy in the coil for your telecoil to pick it up. The output power from a little LM386 is almost nothing.Yes, normal people use. We can use for covert operation.
Yes, I had made an loop. lm 386. Instead of speaker I attached enameled wire with 60 turns.
Its specs for low distortion and a full audio bandwidth are with a gain of 1. You can increase the gain up to 1000 times but the distortion and hiss will increase and the high frequencies will be cut.Lol.it has gain of 1. Lol. Oh man, adding that wont increase the size of our earpiece?
The datasheet for the LM4911 shows that it has 10 pins and shows how to connect them.Also when I saw the earpiece circuit, I just saw one IC with 3 pin one side and 3 pin other side. Total 6 pins. And 4 caps and 2 transistor I guess.
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