LM386 Amp for digital voice recorder

[rizzy_dascal]

Hi,

Could somebody please help me with this amplifier circuit, it is for a digital voice recorder module however some of the instructions have been loosely translated from Chinese and don,t make much sense to me, also are the 2 x 500k resistors right, I can't seem to be able to get hold of these from anywhere.

I am attaching a picture of the schematic

Thanks In Advance

Rizzy

 

[elecbaba]

500K is not critical. Any value above100K is good. These are two seperate circuits for booster amplification. Upper circuit is driven by single ended input and lower by bridge output. Lower requires two signals 180 degree out of phase.

 

[rizzy_dascal]

Hi Elecbaba,

I am trying to connect to speaker output of this module:

**broken link removed**

So could you tell me which one I should use please as it says something about do not connect to ground ! .

thanks
Rizzy

 

[elecbaba]

Why don't you put speaker connections directly to speaker socket on board? It can drive speaker as low as of 8 ohm impedence.
You can find detail about connections on a similar board with ISD1820 chip in english.
Use either SP+ or SP-, leaving the other in upper circuit or connect pin7 and pin9 of chip(speaker output) to input of IC amp(SP+ and SP-) in lower circuit.
GND pin on board will be connected to ground of booster amplifier(pin4 of LM386).
The GND connection you are concerened is the SP+ or SP- left in upper circuit. It should be left floating and not connected to GND as it will short speaker output and cause damage to module.

**broken link removed**

 

[rizzy_dascal]

Am I right in thinking that it is saying use either SP+ or SP- and then have a common ground between amp and board, and whichever SP that you do not use don't connect it to anything ?

thanks
Rizzy

 

[elecbaba]

Thats right

 

[rizzy_dascal]

Hi Elecbaba,

Thank you so much for helping me solve the second post, I wish there were more helpful people on here like you.

Thanks Again
Rizzy