Home Forums General DIY Pedal Discussion SWAH R7 value query

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  • #18291
    mybud
    Participant

    While I’m waiting for these boards to arrive (I ordered 2), I just wanted to verify the value of R27 (listed as the unusual value of 7k9). I’m assuming that the value is actually 7k5. Since my assumptions are not always relaible, please confirm in due course.

    Best to all, Marc

    #18301
    Cybercow
    Moderator

    mybud – a 7K5Ω resistor for R27 will work just fine. It just keeps the bias trim from going to absolute VC with the trimpot.

    #18303
    mybud
    Participant

    HI again CC: To prevent the circuit from switching off the LM13700 at low pot settings, if I understand you rightly?

    Best, mybud

    #18304
    mybud
    Participant

    Sorry CC, been a long day. I see it’s the BC550. Thanks again. Best, mybud

    #18470
    Alex Wylie
    Participant

    Hi there.  This thread started talking about the R27 – 7k9 resistor.  You confirmed a ‘slightly’ lower value would be fine.  How about a 6k8?  I’m having great difficulty finding anyone who stocks that value here in the Toronto area in Canada.

    Thanks in advance for the help.

     

    Alex

    #18471
    Barry
    Keymaster

    Use it. TeePee is always an option as well but that should be fine.

    #18489
    Cybercow
    Moderator

    4K3 and 3K6 1% metal film values are common enough and they can be “tented” (used in a series – as Barry points out) to make up an exact 7K9 value.

    #18549
    Alex Wylie
    Participant

    Hi guys!

    Thanks very much for the responses!  Now to decide…. tented or lower value!

    Thanks again.

    Alex

    #18565
    Jon
    Participant

    I just built one last night with a tent for the very same reason.  Sounds awesome, no issue at all.  Straight up Jerry Garcia.

    EDIT:  I have built a few of these and I find using an external B50k pot for the trimmer very useful.  YMMV and all that.

    #18578
    Alex Wylie
    Participant

    Thanks. Very much for the tips.  I currently have a trim pot installed.  I think I’ll swap it for an external one.

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