{"id":56,"date":"2017-02-14T04:55:59","date_gmt":"2017-02-14T04:55:59","guid":{"rendered":"http:\/\/eequalspi.com\/?p=56"},"modified":"2017-02-14T04:55:59","modified_gmt":"2017-02-14T04:55:59","slug":"the-final-vu-meter-schematic","status":"publish","type":"post","link":"https:\/\/eequalspi.com\/index.php\/2017\/02\/14\/the-final-vu-meter-schematic\/","title":{"rendered":"The “Final” VU-Meter schematic"},"content":{"rendered":"

After all that work, I found that the lower “inerita” of the correctly connected tubes meant that the display itself had a twitchy response — the fix was simple, increase the capacitance at the VU-Meter node. I simply replaced the 0.1uF ceramic caps at the peak detector stage with 1uF electrolytic. Since this is a single rail design, that shouldn’t be a problem.<\/p>\n

Additionally, since the tubes need 5mA instead of 10+ to go full scale, I replaced the 220\u03a9 control current limiting resistors with 1k\u03a9 resistors — the trim pots now sit most of the way to 0\u03a9 instead of most of the way to 500\u03a9 as well.<\/p>\n

The final change was going back to a 10k\u03a9 linear taper potentiometer, instead of a 50k\u03a9 log taper part. This was done because I found that the 50k\u03a9 part was simply too sensitive. On normal signals I’d encounter in real life, the pot stayed turned way down anyway. I had used 10k\u03a9 on the prototype and it just worked better.<\/p>\n

So, with all that in mind, here’s what the final schematic turned out to be:<\/p>\n

<\/a>Figure 1: Final schematic.<\/p>\n

I like this one so much, I may put up a Tindie account and try to sell the stock of the modules that I have parts for. We’ll see if there’s any demand. It’d be kinda neat to have someone actually buy a part that I’ve designed.<\/p>\n","protected":false},"excerpt":{"rendered":"

After all that work, I found that the lower “inerita” of the correctly connected tubes meant that the display itself had a twitchy response — the fix was simple, increase the capacitance at the VU-Meter node. I simply replaced the 0.1uF ceramic caps at the peak detector stage with 1uF electrolytic. Since this is a … Continue reading “The “Final” VU-Meter schematic”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,3,1],"tags":[],"class_list":["post-56","post","type-post","status-publish","format-standard","hentry","category-in-13-vumeter","category-nixie","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/posts\/56","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/comments?post=56"}],"version-history":[{"count":4,"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/posts\/56\/revisions"}],"predecessor-version":[{"id":62,"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/posts\/56\/revisions\/62"}],"wp:attachment":[{"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/media?parent=56"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/categories?post=56"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/eequalspi.com\/index.php\/wp-json\/wp\/v2\/tags?post=56"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}