{"id":353,"date":"2010-02-20T13:42:42","date_gmt":"2010-02-20T13:42:42","guid":{"rendered":"http:\/\/brej.org\/blog\/?p=353"},"modified":"2010-02-20T15:10:55","modified_gmt":"2010-02-20T15:10:55","slug":"napoleon-dynamplifier","status":"publish","type":"post","link":"https:\/\/brej.org\/blog\/?p=353","title":{"rendered":"Napoleon Dynamplifier"},"content":{"rendered":"

I changed the motherboard of my PC a few weeks ago and one problem I have is that the audio line out signal is not amplified. I have this connected to a pair of massive 4 Ohm HiFi speakers which I found in one of the flats I rented. The speakers are not amplified, which is quite annoying as at maximum volume they are still very quiet. The previous board had a software controlled switch to flip the line out to speaker out. The speakers come with speaker wire<\/a> leads, which I just twisted to the exposed wires from an old broken pair of headphones (a proper there, I fixed it<\/a> job). Every so often I would crawl under the desk to re-twist them when I accidentally kick them free.<\/p>\n

So making a small amp would fix two problems in one go. I was looking around the office for a nice box and here is one I found.<\/p>\n

\"\"<\/a><\/p>\n

Sorry Pedro, but this amp is more important than your election. I was planning on stabbing a hole though the metal, but Dave insisted that stabbing things is not allowed due to health and safety rules. Instead he drilled the holes I needed.<\/p>\n

\"\"<\/a><\/p>\n

The circuit is an amp from a a small computer speaker set I had. It is based on two KA2209<\/a> chips. I could have made my own, but this one was perfect.\u00c2\u00a0 These can take quite a bit of punishment. They work from 3V to 15V and use very little power. At 5 volts the board was drawing 30mA. At one point I wired the power and ground the wrong way and the ICs pulled 3 amps, getting incredibly hot in the process. After I corrected the power I was quite surprised to find no damage was done.<\/p>\n

\"\"<\/a><\/p>\n

The holes were relatively easy to expand by rotating a pair of pointed\u00c2\u00a0 tipped pliers inside.<\/p>\n

\"\"<\/a><\/p>\n

For power I used a USB cable I had from a broken PS\/2 to USB converter. USB should give you 100mA without asking, and here we are well within this limit. Most hubs will give the maximum 500mA without any negotiation.<\/p>\n

\"\"<\/a><\/p>\n

I could only find an eight port spring clip speaker wire connector block. Maybe I will expand it to an 4 speaker system later.<\/p>\n

\"\"<\/a><\/p>\n

The metal case is not ideal as you have to insulate it from the board, here done with a piece of paper. I forgot to ask Dave to drill a hole for the audio cable, and I fancied using my stabbing approach without telling him. The method I used was taking a drawing pin and, using my thumb, pushing it through the metal sheet. It actually worked. It is a weird feeling being able to push one metal though another. That’s what it must be like to be a Terminator. You can then expand the hole with a cross head screwdriver.<\/p>\n

\"\"<\/a><\/p>\n

A bit of foam to wedge the board in place and stop it from moving (it was coincidence that it was such a close fit).<\/p>\n

\"\"<\/a><\/p>\n

The USB cable is a little short but that can be fixed with a USB extension lead (plenty around).\u00c2\u00a0 I’m now gonna use it for whatever I wanna use it for! GOSH!<\/p>\n","protected":false},"excerpt":{"rendered":"

I changed the motherboard of my PC a few weeks ago and one problem I have is that the audio line out signal is not amplified. I have this connected to a pair of massive 4 Ohm HiFi speakers which I found in one of the flats I rented. The speakers are not amplified, which […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"_links":{"self":[{"href":"https:\/\/brej.org\/blog\/index.php?rest_route=\/wp\/v2\/posts\/353"}],"collection":[{"href":"https:\/\/brej.org\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/brej.org\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/brej.org\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/brej.org\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=353"}],"version-history":[{"count":4,"href":"https:\/\/brej.org\/blog\/index.php?rest_route=\/wp\/v2\/posts\/353\/revisions"}],"predecessor-version":[{"id":365,"href":"https:\/\/brej.org\/blog\/index.php?rest_route=\/wp\/v2\/posts\/353\/revisions\/365"}],"wp:attachment":[{"href":"https:\/\/brej.org\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=353"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/brej.org\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=353"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/brej.org\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=353"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}