suggest me a circuit for a detector that has a good sound circuit

[algan]

Hello colleagues, please suggest me a circuit for a detector that has a good sound circuit and can hear quiet sounds better. Thus, in this circuit, even with headphones, distant signals can be heard faintly. The important thing is that there are matches to this scheme. I tried two variants from other detectors, but the result was worse than the original.Thanks.

[kt315]

google DUTY CYCLE. in the circuit you boost up the signal NOT by amplifier changing, JUST by right DUTY CYCLE choice. this is NOT amplifier in understanding of a sound amplifier.

A duty cycle is the fraction of a single period where a system or signal is active or "on," typically expressed as a percentage, and represents the ratio of ON time to the total cycle time. For example, a device with a 50% duty cycle is active for half of the time and inactive for the other half, while a system with a 60% duty cycle is on for 60% of the time and off for 40%. The concept is vital in electronics and engineering for determining how long a device can operate without overheating, managing power consumption, and optimizing performance in applications like electric actuators, control systems, and welding machines.

[algan]

Your opinion didn't help me. Thank you.This is what I remember, but I can't find it on Minelab Muskitar, it's interestingly done.

[pito]

lm386 instead of T4

[algan]

I tried it lm386 the sensitivity drops not ok with it

[pito]

Strange, show the circuit, how you connected it

[algan]

[eduardo1979]

Hi Algan. In my humble opinion, the best audio oscillator I've tried so far is the Fisher 1266X, if used in VLF detectors. For PI detectors, the best is the one I use in my detectors that use a CD4046, such as the GS-5 Lite.
Watch the videos on YouTube and you'll find out.
Best regards.

[pito]

connect pin 1 with 8

[GeoMax]

Here are two more LM386 audio circuits...

[Altra]

You need to show us the threshold part of the circuit. It may be limiting the full volume to the output amplifier.

[algan]

You need to show us the threshold part of the circuit. It may be limiting the full volume to the output amplifier.

This is the diagram, there is a coarse threshold and a fine threshold. When I am without headphones, the LED reflects a signal, but I have to hold the speaker to my ear to hear it. The near signal is clearly audible, and when I wear headphones, the far signal is audible at the same time as the LED, but also weakly. What correction can I set on the threshold? Thanks. And the second diagram is missing the LED and the fine threshold, the rest is the same.

[GeoMax]

Have you ever tried using a different speaker, perhaps 8 ohms instead of 32 ohms? Or a piezo speaker? Perhaps the designer of the schematic used a "standard symbol" from their component library that doesn't correspond to the actual speaker in use. I see this kind of thing regularly in schematics.

[Altra]

It looks like they used the fisher 1265/66 audio as Eduardo suggested. The target signal modulates the audio pulse width as kt315 mentioned. This circuit is sensitive to over modulation. If the duty cycle goes over 50% it actually starts to mute the audio. I would monitor the output of the lm393 with an scope. Experiment with different values for R16 and P1.

[Carl-NC]

You need to look at the signal at IC5a with an oscope, see if the modulation is changing sufficiently with signal strength. Personally, I don't like using PWM as the way to modulate volume as it also changes the timbre of the sound and can make faint targets harder to hear. I prefer a constant 50% square wave and then use the envelope of the detected signal to control the loudness.