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Building your own stompbox / Re: Intersound IVP gyrator circuit output
« Last post by ElectricDruid on May 31, 2023, 05:09:01 PM »
Do these gyrators work with the resistances tied to ground? I've seen it done that way, but I think in those circuits we might have been looking at a dual supply.

Since this is a single supply, shouldn't those go to Vbias/4.5V instead? I think that ground connection is going to screw it up.

Try posting on Modwiggler rather than here. This is more up their street.

As a first guess, I think you need to be searching for "Lunetta noise synths". The six controls looks like simple hex invertor oscillators to me, with switches to bring in different logic chip combinations (AND, OR, XOR, etc) and buttons to feed different signals to the output. It's probably not half as complicated as it sounds.
Building your own stompbox / Re: Old telephone ringer stompbox
« Last post by Phend on May 31, 2023, 04:45:23 PM »
A Ling ?
Building your own stompbox / Re: pedal building education
« Last post by FSFX on May 31, 2023, 04:33:21 PM »
I publish a document called 'Where to get everything' on a couple of the guitar pedal FB groups.
As well as links to useful component suppliers, it has loads of links to learning resources for pedal builders.
I have made the latest version available for download on my website.

The file is at
Building your own stompbox / Re: pedal building education
« Last post by Mark Hammer on May 31, 2023, 04:07:20 PM »
May I also suggest that someone starting out learn how to properly use their DMM?  For measuring resistance, voltage, and current at minimum.  It is a little *boring* to take the time doing this basic thing, but it's VERY likely to pay off big time later!    Youtube has many videos you can find.
And make yourself an audio probe.  This is just a regular guitar cable, but the phone plug is removed at one end.  An alligator clip is connected to the ground lead, and a capacitor with a nice stiff lead is connected to the other end.

What's it for?  You can plug some audio source into the pedal circuit board, connect the cable alligator clip to a suitable ground connection and then use the free end of the capacitor to probe different informative parts of the audio path to hear if there is signal passing.  The capacitor block any DC from reaching your amplifier.

It's not the be-all and end-all of troubleshooting, and is not a replacement for things like using your meter to measure voltages at critical locations, or continuity (both of which can be applied after a preliminary probe).  But it can be VERY helpful to know you have signal at this point, at that point as well, but it stops at THIS point in the circuit.
Building your own stompbox / Re: Flintlock Flanger not Sweeping
« Last post by matopotato on May 31, 2023, 04:01:19 PM »
explain again to me what happens at S C T - is S always connected to something. or just left open?

And what if I connect T to C or C to S? C-S ought to change the total R for IC8 and thus change its result?
T to C I do not understand. Perhaps T C and S are all connected to some extent when the expression pedal is connected...
MANUAL is supposed to set the "delay time range", but like I wrote earlier, nothing I can detect. Perhaps if I can get ti to flange and lose the thump that might be clearer.

this. the very purpose of a circuit diagram is to explain the circuit connections. how hard is it for the draughter to include the jack switching arrangement? it does make sense for TSC to be some sort of shorting jack, but that's not for us to guess at. grrrrrr.

The switching jack

The Tiger colored goes to "T". It will go to the Tip of the expression pedal if engaged, else it does not go anywhere
The redBlack goes to S (=Svart, Swedish for Black)
And the Candy colored to C (red-white). So C and S are connected by default.
With an expression pedal C and S are disconnected directly and the expression pedal will provide varying R I think.
Black wire is to ground and sleeve of expression jack.

I am truly sorry for not explaining this better earlier and for the frustration this caused.
Building your own stompbox / Re: Flintlock Flanger not Sweeping
« Last post by matopotato on May 31, 2023, 03:52:20 PM »
With less than full Range, Manual has an effect. Thanks @ElectricDruid.
The Bias trimmer has effect on the thumping, but does not dial it away, but rather change character between clicky and thumpy.
I still think I should be able to find out what causes the thumping problem, and then hopefully the sound will also be more "flangy".

I manage to buy one CD4007, one CD4049 that I tried in, but no change.
I also tried a new 78L15, but no change either.
Then I was going to try changing the 2N5457, but it is a bit more costly in my shop for a random swap test, so i googled that (among others) BF244A might be a replacement, and that was cheap enough to try.
And now the thumping went almost all away, but quite a murkier sound. So clearly not a 1-1 replacement in this case.
I got an SMD 2N5457 and I have some adapter I will try later on, or just buy the TO-92 one. So a bit more hopeful, although it might well turn out to be the same problem with a proper swap of the Q1.
Strangely, the pinout says DSG, but my meter has it GDS and that would not have fitted on the PCB without twisting some legs around in either prepared slot.
And it seems to work as the standard pinout (DSG).
Building your own stompbox / Re: Intersound IVP gyrator circuit output
« Last post by PRR on May 31, 2023, 03:33:50 PM »
Why is IC3 pin 3 so low? Since it comes from off-the-image, we need more clue.
Building your own stompbox / Re: Score...again.!
« Last post by PRR on May 31, 2023, 03:30:11 PM »
pic of those caps?

Not just "gum". Adams Chiclets.

Building your own stompbox / Re: Am I missing something..??
« Last post by PRR on May 31, 2023, 02:53:14 PM »
Might sound unpleasant imho with 7k input impedance...

Direct from e-guitar, 7k load is just a bit weak and no-treble, not necessarily unpleasant. I agree it looks very odd today.

It does have the whiff of hasty-fix for a LM386 amp that was OK with any amplified thing but a bit shy on raw guitar. It was not sold for that, but people don't know "level" or "impedance" and a $1.50 add-on makes some sense.
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