headphone amplifier with microphone input

[MrDEB]

I ordered a kit from Amazon

Amazon.com: Velleman, Inc – Super Stereo Ear MiniKit MK136 – Entry Level Audio Amplifier Soldering Project : Electronics

Amazon.com: Velleman, Inc – Super Stereo Ear MiniKit MK136 – Entry Level Audio Amplifier Soldering Project : Electronics

www.amazon.com

Hopefully this will work as desired
or see attached file with LM386

 

[AnalogKid]

Delete

 

[AnalogKid]

Hopefully this will work as desired

So, tell us your desires.

ak

 

[MrDEB]

to assemble a headphone amplifier that has a microphone as the audio input but not panning to use a pcb. (to $$$)

Audio Amplifier Projects and Design Tutorials

Learn how to design audio circuits, choose the right components, and optimize sound quality with our in-depth audio amplifier project guides.

www.circuitbasics.com

 

[AnalogKid]

Velleman is usually a decent kit company, but the NE5532 has a minimum power supply voltage of 10 V (or +/-5 V), not 4.5 V.

Are you looking for a circuit to hand-wire on perf board, or a module / kit to purchase?

ak

 

[MrDEB]

I am looking at hand wiring since pcb are to expensive.
I ordered the Velleman kit but looking at circuit using the LM386.
My goal, due to bad hearing, is to construct a headphone amplifier that does not use blue tooth.
Has capabilities of 2 persons.
post#1 has schematic of amp using the lm386

 

[For The Popcorn]

There are some affordable US options for SMALL board sizes. See this post.

 

[AnalogKid]

Both 386 schematics have only one channel, and nothing at the input to combine the L and R of a stereo signal into a mono output.

To have outputs for two persons, won't you need two volume controls?

Everything you have mentioned so far certainly is doable, but the size of the circuit increases with each added detail. What are your expectations for battery size and runtime?

ak

 

[Les Jones]

Many years ago I built an amplifier that may be similar to your not very well defined specifications.
It was for two of us to listen to plays and talking books (From a cassette player.) It was two channel stereo with a volume contol for each output and one output combined the two cannels into mono. I have just had a look at it and found that I used 2 TDA2822 (Stereo on a single 8 pin chip.) This chip works well with a 3 volt supply (2 AA cells) I had alook on ebay to see if this chip was still available and it is. There also built modules using this chip. This is one example.
https://www.ebay.co.uk/itm/12705603...01K1T342VXEHY8QCDS2D0P3C9G&hash=item1d9521381
If you are using this with a microphone input then why do you need stereo ? Or do you mean that it also has a wired stereo input.
Les.

 

[MrDEB]

My plan was to have 2 separate outputs. going to experiment with one first. If it works as desired then just put two of same on one board. The TDA2822 sounds promising. thanks

 

[Nigel Goodwin]

I am looking at hand wiring since pcb are to expensive.
I ordered the Velleman kit but looking at circuit using the LM386.

The Velleman kit is probably all you need, just for feeding headphones you don't really need a power amp, many opamps are plenty loud enough for headphones. One of our products at work uses headphones, I use a bridged TL072 opamp to feed them, and actually have a 100 ohm resistor in each headphone lead (one in ground, one in signal - the headphones are strapped in mono) - it's more than loud enough.

 

[MrDEB]

I just ordered some TDA2822 assembled boards to see just how well they work.
I may need to adjust for the headphone impedance.
3 assembled boards for $10

 

[Nigel Goodwin]

I just ordered some TDA2822 assembled boards to see just how well they work.
I may need to adjust for the headphone impedance.
3 assembled boards for $10

The only 'adjustment' required is where you set the volume control.

 

[MrDEB]

here is the schematic using the TDA2822D013TR

 

[AnalogKid]

The Zobel networks (R3, R4, C6, C7) should come before the output coupling capacitors.

What are the purpose of C11, C12, R7, and R8?

Also, traditional schematic signal flow is from left to right, not right to left U-shaped.

ak

 

[MrDEB]

this will explain post#15 questions
file:///C:/Users/dougb/Downloads/TDA2822M%20_%20D2822A%20_%20KA2209%20DIY%20Guide%20-%20Simple%20low%20power%20stereo%20amplifier.html

 

[AnalogKid]

That looks like a link to a file on your computer, not the innergoogle.

Also, I know that the 2822 datasheet shows them after the coupling cap, but the way more common location is what is shown in you LM386 schematics. This is partly to keep the coupling cap characteristics from affecting the Zobel network calculations and altering the phase correction seen by the negative feedback loop.

ak

 

[MrDEB]

not sure what is going on with link?
I bookmarked the page.
file:///C:/Users/dougb/Downloads/TDA2822M%20_%20D2822A%20_%20KA2209%20DIY%20Guide%20-%20Simple%20low%20power%20stereo%20amplifier.html

 

[Les Jones]

You have no load resistor on the electret microphone and no supply to the top of the load resistor.
With the suggested (In the microphone dataheet.) load resistor of 2.2 K C11 and C12 will attenuate frequencies above about 100 hz. What is their purpose ? Depending on the volume of the sound to be amplified and the sensitivity of the microphone you may need another gain stage between the microphone and the TDA2822 input.
Les.

 

[Les Jones]

Re the link in post #16. As AK says that link is to a file that you have downloaded into the default download directory (folder.) from your browser. To get it to the forum you will have to display it on you computer then do a screen capture of the screen . That will give you a picture file with the extension .jpg, .png etc. You will then use that file to insert an image to your post on the forum. It would be easier if you posted a link to the url from which you downloaded it.
Les.