Menatone Pig  [traced]

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FiveseveN
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Post by FiveseveN »

How are you measuring them?
Ignorance more frequently begets confidence than does knowledge. (Charles Darwin)

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Clyngedal
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Post by Clyngedal »

This is acrually my first post on this forum. As a big Ronson-fan I gotta have a Pig, so I decided to try and build one from this layout. I'm ordering parts right now :)

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Post by engineelite »

FiveseveN wrote:How are you measuring them?
I just used a multimeter on the NPN side

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FiveseveN
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Post by FiveseveN »

Yeah, that's not going to tell you anything meaningful: it divides collector current by base current, but for FETs the "base current" is basically zero, they are voltage-controlled devices.
PS: here's a discussion about characterising JFETS: http://stompville.co.uk/?p=112
Ignorance more frequently begets confidence than does knowledge. (Charles Darwin)

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The Rotagilla
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Post by The Rotagilla »

Dr Tony Balls wrote:
sinner wrote:
agoldoor wrote:Anyone care to do a vero for this? Bee dot? Sinner?
No, not me, not now. I'm quite bored with FX units recently, I'm sorry bro

I'm inches away from doing a turret board layout and build for a Marshall Pig...
Do you have a legit schematic of the Pig? I've never been able to find one.
The television will not be revolutionized.

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shooto
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Post by shooto »

I have the same gain problem...anyone find a solution?

thanks

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johnk
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Post by johnk »

I just drew up a PCB for it and can confirm that the tagboard schematic has an error. the 22n that goes to lug 3 of the gain pot on Q4 should be connected to the DRAIN and NOT the source. It has much more gain that way. this was posted earlier in the thread.

here's my verified PCB layout and a PCB that is 800dpi:
Attachments
0001-Pig Layout Verifed.png
0001-Pig PCB FINAL.jpg

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johnk
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Post by johnk »

...and if you want still more gain, add the 22uf cap in parallel to R19.

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Post by johnk »

The Rotagilla wrote:Bumping for some questions and new info.

I had access to a Pig built this year and had a question. Turret Board's schematic shows a 22nf going from Q4's source to Lug 3 of the Gain control. In the version I have, the 22nf seems to go from the drain to Lug 3 of the Volume control while there's an added 22uf to ground from Q4's source (in parallel with R19). I may very well be wrong, so please correct me if I am. Also the following changes were noted...

C12- 500p
C13 - Omitted

R2 - 33k
R5 - 27k
R15 - 33k
R18 - 33k
R21 - 33k
R25 - 33k
R27 - 10k
I tried these values in mine and the Jfets bias up A LOT better with them anf the circuit sounds much nicer. I din't find the need to replace R2 or R27 (the input and output resistors) but thanks for posting the info!

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Post by johnk »

just finished boxing mine up. since it runs on 18V I added an internal charge pump and a relayed true bypass:


Image

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Post by johnk »

update: i did find the pedal to sound a little dark so i replaced C18 (a 4n7) with a 3n3 and i like it a lot better now which is pretty much like having R27 being a 10K with the 4n7.

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The Rotagilla
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Post by The Rotagilla »

johnk wrote:just finished boxing mine up. since it runs on 18V I added an internal charge pump and a relayed true bypass:


[ Image ]
That's really sharp looking.
The television will not be revolutionized.

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Post by sanfi4u »

johnk wrote:just finished boxing mine up. since it runs on 18V I added an internal charge pump and a relayed true bypass:
[ Image ]
Your pedal looks killer! Is the box design hand made with a Dremel? I'm sure it sounds on par with the look too.

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Post by johnk »

sanfi4u wrote:
johnk wrote:just finished boxing mine up. since it runs on 18V I added an internal charge pump and a relayed true bypass:
[ Image ]
Your pedal looks killer! Is the box design hand made with a Dremel? I'm sure it sounds on par with the look too.

the pedal enclosure was etched with an etching solution.

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Post by rhinson »

johnk wrote:update: i did find the pedal to sound a little dark so i replaced C18 (a 4n7) with a 3n3 and i like it a lot better now which is pretty much like having R27 being a 10K with the 4n7.
hey there, i just built one of these with your board layout and it works great. just wondering (since you used the values the guy posted from a later unit with regard to drain values, etc.) did you leave in both 100pf caps or did you omit the one omitted that the guy posted? i'm asking because i have a high pitched whine that gets louder as i turn up the gain and/or the treb. controls. just wondered if you encountered this at all. i thought it might be the charge pump (type, grounding, etc.) but i don't think this is the case. btw, can you post the tagboard schematic----i see it alluded to in this thread but can't seem to find it. thanks rh

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johnk
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Post by johnk »

I built it just like the PCB that I posted. mine has no issues at all.

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Post by rhinson »

johnk wrote:I built it just like the PCB that I posted. mine has no issues at all.
hey there, thanks for the reply. so all you changed in the end from your parts initially installed on your layout was just the drain resistor values and kept everything else as posted in the layout? rh

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Post by johnk »

I actually ended up changing one of the 100pf caps to a 10pf for more top end:
Attachments
0001-Pig Layout NEWEST.png

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Post by rhinson »

johnk wrote:I actually ended up changing one of the 100pf caps to a 10pf for more top end:
cool thanks man. do you know what you set the 100k trimpot to? didn't have a trimmer that would fit so i just stuck in a 27k resistor, however the bass ch seems like it's not as loud as the treb ch so i was wondering about that. rh

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modman
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Post by modman »

rhinson wrote:do you know what you set the 100k trimpot to? didn't have a trimmer that would fit so i just stuck in a 27k resistor, however the bass ch seems like it's not as loud as the treb ch so i was wondering about that. rh
dude, nobody can tell you, because it depends on the particular characteristics of the jfet. alternatively, connect a similar value potentiometer to that spot, set the correct resistance by testing. the desolder the pot without changing the setting and measure it. then you know the resistor value to use with you particular setup.
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