Hi,
I would like to connect an headphone HPD11 to this module.
How can I connect an headphone in such a way that I also can change the volume?
If it is not possible to connect the headphone directly can I modify the MK136 so that I connect the MP3 player VM202N to it?
I hope someone can help me.
Kind regards, Reinier
VM202N is not suited to drive a low-impedance headphone.
You could modify MK136.
(remove mic’s and resistors R1 & R2, change R14 & R15 to 2K2)
Hi,
Thank you for your advice.
I was thinking the same way. Now I get a little background noise. Mayby is the R14 en R15 to much.
This will only reduce the Amplification.
How can I reduce the background noise?
Kind regards, Reinier
Hi,
How can I change the Amplication? With R14 and R10.
What is the normal resistant for R10?
Thanks for your help.
Kind regards, Reinier
Hi,
I found the little background noise. It is the USB adapter I use instead of batteries.
Maybe with an elco I can reduce the drift a little bit more. What do you advice?
I build three MK136 with VM202N and HPd11 headphone. The sound is really good.
I Change the resitors. R10 & R12 to 2k2 and R14 & R15 to 1k.
If I am correct is the amplifier about 1,5x
Kind regards, Reinier
Gain = 1 + R15/R12
Unit has been designed to run from batteries.
It needs a really smooth DC voltage.
We’d recommend a regulated PSU with transformer.
You could try adding a 1000µF cap.
Hi,
Thank you very much for this issue. I appreciate your support.
I can now finish this project and I am satisfied with the result.
You are doning good work.
Kind regards, Reinier
Not to hash up an old thread but was there any concrete resolution to powering the MK136 with a USB charger? Adding an additional cap, etc.
Since USB chargers are rechargeable and cheap these days they’re more economical the AAs, even rechargeable AAs. A resolution to this would be great.