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Changeover?
D1 & D2 connect AFTER the 1k R4 at C4 instead of at the amp output.
Change over switch to either connect the diodes as it is at the amp - input OR via 10uF (as per Hollis) to 0v.
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Building your own stompbox / Re: Tape Saturation Pedal Idea
« Last post by Barracuda on Yesterday at 11:56:31 PM »
I did not know that about Fleetwood Mac! glad to hear it can be done in hopefully the same or a similar way.

Funny you should say about the mid/high frequencies, because it was probably the pass filter(s) making it such a smooth distortion. I mean I see no clipping diodes, so technically we are talking a fuzzy distortion?
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Building your own stompbox / Re: J201 weirdness
« Last post by anotherjim on Yesterday at 11:38:22 PM »
Let's put these two together.


The English Channel has trimmer controls for drain resistors. Why? Because the FET transistors have large variations, even in the same production run. At bottom left is an instruction to adjust the trimmers for 4.5v at the drain. It is possible to select the FET's to suit fixed resistor values, the builder of the original you have traced may well have done that - or wished for good luck.

The Drain resistor alone sets the voltage gain IF the Source resistor is worth zero. But the Source resistor also helps to achieve the right bias by raising the Source voltage relative to the Gate voltage which is 0v. Note that the Gate has no positive voltage supply, it is "tied" to 0v by some resistance.

The FET channel (drain to source) is NORMALLY conducting and to be controlled, the Gate voltage needs to be some amount below the Source voltage to turn the channel towards a high resistance, a condition called "pinch off" or "cut off". The amount of voltage needed is called -Vgs in specifications. You cannot set the Gate any lower than 0V, so the Source voltage must be raised above 0v. Raising Source resistance to achieve a good bias will subtract from the available gain.

A 22uF capacitor has low impedance at guitar frequencies. In parallel with the Source resistor it performs a magic trick. DC bias is not changed since the 22uF does not pass DC. However, the Source resistor is bypassed by the AC signal through the capacitor - so gain is increased for AC signal.
Putting a resistor in series with the 22uF "bypass" capacitor - your 1k (R18) limits signal gain a bit, it lets the 22uF increase signal gain, but not by as much.

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Building your own stompbox / Re: Tape Saturation Pedal Idea
« Last post by Heikki on Yesterday at 10:50:42 PM »
I don't know much about tape recorders but the amplifier circuit seems fairly simple. Lots of fain going on so it's easy to drive to clipping with guitar. R155 seems to be tone pot and if switches 103, 104 are on the position where drawn, when tone pot turned halfway there's 40dB gain in mid and high frequencies and even more gain at bass. Then theres volume pot and power amp with 50dB gain. What makes it sound great probably has lot to do with the frequency response of the amplifier.

All NPN transistors and single sided power supply, you could easily do a similar pedal that works with 9V.
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Building your own stompbox / Re: Help Debug an EA tremolo
« Last post by bluebunny on Yesterday at 08:57:08 PM »
what's the appropriate manners dictate after the forum help you find the problems and enlighten you?
buy everyone a round of drinks? do some summary for the next NOOB builder?  bake a cake?

Cake??   :icon_eek:    No, this:

   :D
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Building your own stompbox / Re: Taking the powder coating plunge !
« Last post by davepedals on Yesterday at 08:48:49 PM »

Small update well I have received my powder coating equipment, gun , and several paints to experiment with. Naturally I forgot my clearcoat! Although you don't really need it with that many colors I completely forgot about clearcoating my labels! Well doh!

Have read a few articles that concern me lately about clearcoating labels . Using powder coat methods of course, the fact that many people are having problems with yellowing . But again other articles I've read state that the problem is because these people were using inkjet waterslides which must be coated with acrylic spray, and that it's the acrylic paint that is actually yellowing, not the water slide material itself . But I guess I have that in the pocket since I use a laser printer anyway along with a laser medium waterslide. Still it has me wanting to do what I've done the last 20 years of my life, have a backup plan!

About 12 years ago I played around with screenprinting, lots of fun Only did two color printing but it was easy , cheap , and really got great results with it since you have so many different mesh sizes to get different I guess you would say DPI resolution out of what you're printing. So why not make a small screenprinting jig for different sized enclosures? Then I can simply purchase UV curable ink for screen printing? I'm pretty darn sure they sell it , and I could build a UV exposure cabinet for probably 25 or 30 bucks . I think there are several manufacturers of pedals out there that use this method.

Anyway as I began , I have all my materials and equipment but have not painted a single enclosure yet. My garage is really junky and that's going to be my work area. I have a lot of spring cleaning to do but I'm hoping in the next week or two I'll have photographs to share some of the enclosures I have powder coated .
Prost!

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I use nippers, and as Paul noted, I lose one every now and then. No great loss.
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Building your own stompbox / Gaussmarkov spring reverb build
« Last post by MKD on Yesterday at 08:10:22 PM »
Hey all,

Planning on building this reverb http://gaussmarkov.net/wordpress/circuits/spring-reverb/

And wondering if i can sub out the specified 8ab2a1b accutonics/mod reverb tank for one of the accutonics blue reverb tanks??

Original tank - https://www.amplifiedparts.com/products/reverb-tank-mod-8ab2a1b
New tank - https://www.amplifiedparts.com/products/reverb-tank-accutronics-amc-2bf2

Input/output impendence on the original is 10ohms/2575ohms, the blue reverb is 150ohms/1500ohms

reason is purely down to size of the tank. Id like to put it into a pedal and it not be as huge as the van amps one (large version..)

So....can i use the blue reverb tank, or what do i need to do to the circuit to make it so i can use the blue reverb tank...


Thanks!!
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> cost per hole is under zero

Not really. The source cited seems to be $0.25/hole. Making three-fers for transistors would be a buck a transistor, using the waste-one cutting technique.

I must admit my remarks came from days when we used these strips by the thousand-pin baggie, and didn't usually cut as few as three holes.
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Building your own stompbox / Re: Tape Saturation Pedal Idea
« Last post by Frank_NH on Yesterday at 03:10:50 PM »
Funny you should mention this.  I'm a big Fleetwood Mac fan, and I know Lindsey Buckingham used the guts of a Sony TC-630 tape desk to create the "fuzz" used on the first Buckingham-Nicks era Fleetwood Mac albums (e.g. "Go Your Own Way" from Rumours).  Read about it here...

"For amplifiers I used to use HiWatts, but they all of a sudden somehow became real dirty-sounding. So I got Marshall 100watts, and they seem to have a lot of bite. I use these tape recorder guts for fuzz. When I got out of Fritz and started doing lead, I bought a Sony 630 tape recorder deck for demo tapes. Then I got an Ampeg 4-track and started using the Sony 2-track for slap echo and effects like that with the preamp output of the deck into an amp. It's just an amazing fuzz device. Since then I've taken the guts out of the preamp and put them in a little box, and that's what I use both onstage and in the studio."

http://bla.fleetwoodmac.net/index.php?page=index_v2&id=32
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