SWAH R7 value query

[mybud]

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

[Cybercow]

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

[mybud]

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

Best, mybud

[mybud]

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

[Alex Wylie]

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

[Barry]

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

[Cybercow]

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.

[Alex Wylie]

Hi guys!

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

Thanks again.

Alex

[Anonymous]

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.

[Alex Wylie]

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

[Author]

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