Velleman project combining plus upgrade

Discussion in 'The Projects Forum' started by Andy Larson, Jul 20, 2016.

  1. Andy Larson

    Thread Starter Member

    Mar 26, 2015
    I have two little solder project kits I built awhile ago. An environment noise amplifier and a radio kit. I want to do several things.

    One: Reconnect the speaker wire on the radio to output to the amp (has two input mics).

    Two: reconnect the headphone 2.5 jack to a 10W speaker. Problem being that the radio has only got a .5W speaker

    Three:* Consolidate the circuit power source down to a 12V AC to DC converter.

    Four*: Ideas on getting a very clean radio signal? I currently have a ferrite choke on the radio antenna. I also have other ferrite torids and cermaic torids (the doughnut shaped ones) plus one more ferrite choke

    * = optional
    Schematics (best I could find)
    The Radio (Velleman MK118)
    Schematic is in the lower right corner of the pdf below

    The amplifier (Velleman Mk136)
    Schematic is in the lower right corner of the pdf below
    Last edited: Jul 20, 2016
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    Pictures of your velleman kits and circuit diagrams, will get you better results...
    Last edited: Jul 20, 2016
  3. Sensacell

    Well-Known Member

    Jun 19, 2012
    Yes indeed, you should assume the reader has no idea what a "Velleman kit" is, I have no idea.

    If you make me work to even understand what you are asking for, my enthusiasm level becomes rather low.
    We all do this mostly for our own pleasure and satisfaction in helping people, but you need to meet us half way.
  4. tracecom

    AAC Fanatic!

    Apr 16, 2010
    There are some problems with what you want to do. The MK138 is a radio receiver with a built-in amplifer (LM386N.) As you may have discovered, the LM386N is not a very powerful amplifier, but its output is suited to power a small speaker (.5 watt.) The output from the LM386N is monaural, not stereo.

    The MK136 is an audio amplifer that is designed to power a set of headphones. The output from the MK136 is stereo, not monaural. Combining the two stereo inputs can be done easily with minimal loss of signal, but the signal level will still be too low to power a 10 watt speaker.

    Your best bet would be to find a 10 watt amplifier and connect the output of RV1 on the MK138 to the input of the new amplifier.

    MK136 Schematic.JPG
    MK138 Schematic.JPG
    Last edited: Jul 20, 2016