From FB group Building Transistor Radios 2018-09-28<\/p>\n
I see nothing wrong with using the ‘386 to directly drive the power output stage. It’s cheaper than a transformer.<\/p>\n
But I was thinking about how the current was flowing in the ‘386’s output transistors. Normally an electrolytic capacitor blocks any DC from flowing out of pin 5. But when the ‘386 is used to directly modulate the final, the current that would normally flow through the chip’s bottom (current sink or pulldown) transistor instead flows out pin 5 and through the final. The bottom transistor is not doing anything, it can’t current sink or pulldown because the pin 5 has current flowing out only, nothing flows in to be sunk or pulled down. So the ‘386 is effectively running as a current source with just the top (current source or pull-up) transistor.<\/p>\n
The point is that the ‘386 chip could be replaced with a single transistor, or two if more gain is needed.<\/p>\n","protected":false},"excerpt":{"rendered":"
From FB group Building Transistor Radios 2018-09-28 I see nothing wrong with using the ‘386 to directly drive the power output stage. It’s cheaper than a transformer. But I was thinking about how the current was flowing in the ‘386’s output transistors. Normally an electrolytic capacitor blocks any DC from flowing out of pin 5. <\/p>\n (Read More…)<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7,261],"tags":[],"class_list":["post-13102","post","type-post","status-publish","format-standard","hentry","category-radio-frequency","category-transmitter"],"_links":{"self":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/13102","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=13102"}],"version-history":[{"count":1,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/13102\/revisions"}],"predecessor-version":[{"id":13103,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/13102\/revisions\/13103"}],"wp:attachment":[{"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=13102"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=13102"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rustybolt.info\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=13102"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}