• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

audio driver

Status
Not open for further replies.

OutToLunch

New Member
I've been playing around with the LM386 with an electret mic as input and an earbud as the output but it clips/distorts way before it can get any real volume. Is there a better audio amplifier for headphones/earbuds?

without a schematic, i can throw out some details...

12V bias

INPUT:
2.2k to the electret
1uF dc blocking cap
40k log pot w/13k in parallel to get no more than around 10k across it

OUTPUT
10 Ohm and .056uF in series to ground from LM386 output
560uF cap to earbud

LM386 decoupled with 0.15uF ceramic
 

Zerotology

New Member
I've heard the 386 touted as the audio amp and others say it's only good for use as a power amp. I suspect that since you're having a problem, that's what it is. It's good to boost a power supply or something but not good at boosting a signal.......
 

audioguru

Well-Known Member
Most Helpful Member
The website "Headwize" has some projects with opamps having a low power supply voltage driving headphones successfully.

The volume into a 32 ohm earbud when its amplifier has a 9V to 12V supply should be almost deafening before it distorts.

Please post your circuit's detailed schematic and say the brand and model number of your ear bud headphones.
 

OutToLunch

New Member
thanks for the help, guys, but I looked at the horrible power supply I was using and it was only rated high enough. At peak output power, the supply couldn't keep up. I swapped it out for one with higher ampere capacity and its all good now.

I have another question, though, regarding noise injection from the power supply. The supply I'm looking to use will be really noisy (12V rail from a motorcycle). I would rather not use batteries, although I understand they would be the quietest. What would you recommend for reducing the noise from the 12V rail? A linear regulator to 9V? Common mode choke on the input? What do the car radio mfg's typically do?

Thanks
 

Chippie

Member
The supply I'm looking to use will be really noisy (12V rail from a motorcycle). I would rather not use batteries, although I understand they would be the quietest. What would you recommend for reducing the noise from the 12V rail? A linear regulator to 9V? Common mode choke on the input?
Thanks
a 9v reg hasnt got enough headroom running from the '12v rail' as you put it....

If you run the amp of the bike's battery you should be ok....If you were to acquire a broken car radio you could take the parts from it to make a filtered supply....
 

OutToLunch

New Member
a 9v reg hasnt got enough headroom running from the '12v rail' as you put it....
I would beg to differ on that - especially since there is no point in using the amp if the bike is not running which means the rail would be over 13V. Even an old 7809 can handle that.

If you run the amp of the bike's battery you should be ok....If you were to acquire a broken car radio you could take the parts from it to make a filtered supply....
so, aside from finding an old car radio, do you know what the filters consist of for quiet operation? are they simply LC filters? Common mode chokes to get a separation on from the chassis as well? perhaps they use switch mode supplies? Are they a combo of filters and regulators? inquiring minds want to know!
 
Last edited:

Chippie

Member
I would beg to differ on that - especially since there is no point in using the amp if the bike is not running which means the rail would be over 13V. Even an old 7809 can handle that.
QUOTE]

Right again...:( the drop out is only 2 volts...

Filters are basically LC.
 

OutToLunch

New Member
yeah - I used an LC filter on the input and then an LM317 and all the buzz is pretty much gone. I may want more volume but I have to try the speakers in my helmet while I'm riding to really see what is needed.
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top