Wednesday, 6 February 2013

Vulcan Overdrive

And the BJT version for those who prefer them to JFETs




Version without trimmers which allows you to keep the board size down:



11 comments:

  1. With this being for BJTs instead of JFETs would it be possible to just sub in a fixed resistor as I'm guessing biasing isn't as important? If so are there any values you'd suggest to start off with and then we can tweak from there? Or would you still suggest a trimmer?

    ReplyDelete
    Replies
    1. Biasing the transistors is still important, they're just not as temperamental. But the schematic called for a 10K for all the collector resistors so yes you could just do that, I left the trimmers in so that it can still be fine tuned. You could obviously leave out the 3 little links as well.

      Delete
    2. I've added a non-trimmer version because it will save you a few columns

      Delete
    3. Thanks Mark, to be honest my main concern was my total lack of trimmers in my stash. I think it's something that I'm going to have to address soon.

      Delete
    4. I got quite a few from eBay and paid around £6 per hundred delivered so it's something that's worth having in stock and won't break the bank. If you want to keep the number you have to get down to a minimum consider getting some of the multiturn trimmers (that look like the ones shown in the layout) in either 50K or 100K. Because they are multiturn there is still a lot of sensitivity lower down in the values so there would be no problem in using is where a 10K or even 1K trimmer is called for.

      Delete
    5. Thanks for the heads up, since I've only been building since I've only been building since around September last year I've been trying to build my stash bit by bit, I'm not sure my Girlfriend would be delighted if we couldn't pay the mortgage because of my 'awesome transistor collection'. Trimmers have been pretty near the bottom of the list but it's getting to the point where I've nearly got everything else. To the ebaymobile!

      Delete
    6. Just order them the next time she comes home with a new pair of shoes :o)

      Delete
    7. Hahaha, surprisingly she's not a shoe fiend but she has got a fairly hardcore ASOS addiction so it's not a bad plan.

      Delete
  2. Looking at the layout I think it's easy to replace the axial cap by a regular radial one by moving end tip of d4 5 rows up, moving the cap to column 2 rows 1 and 3, and adding a link from 4/3 to 4/8

    ReplyDelete
    Replies
    1. Yes or you could just use a radial cap with the leads spread out if you want. I only included that because there was plenty of space and I have axial caps that are exactly that size

      Delete