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Author Topic: "J20" (K-20X Preamp, only OD and with 071 instead of 072)  (Read 26944 times)

phatt

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Re: "J20" (K-20X Preamp, only OD and with 071 instead of 072)
« Reply #30 on: January 11, 2011, 09:46:22 AM »
Yep a pain until you get how it works,, and darn I still get tricked some times.  :loco
223 would most likely mean, 22nF or .022uF or 22,000 pF all the same.

First two numbers are the *Value* 3rd number is the multiplier.
in this case it's 22 now just add 3 zeros and presto it's 22nF

333 same again 33nF
Phil.

joecool85

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Re: "J20" (K-20X Preamp, only OD and with 071 instead of 072)
« Reply #31 on: January 11, 2011, 09:54:39 AM »
So 333M and 333 would both be 33nF?
Life is what you make it.
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phatt

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Re: "J20" (K-20X Preamp, only OD and with 071 instead of 072)
« Reply #32 on: January 11, 2011, 10:00:57 AM »
Yep I'd say so,
M is the voltage rating of the device.
Can't remember them all off hand but I think *J* means a 100volt rating.

Some makers use different codes but after a while you catch on to the tricks.
Phil.

Ed;
the code Works like this;

 uF  nF  pF
000,000,000

So a 100nF would read 104,, that's 10 and just add 4 zeros
« Last Edit: January 11, 2011, 10:05:50 AM by phatt »

joecool85

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Re: "J20" (K-20X Preamp, only OD and with 071 instead of 072)
« Reply #33 on: January 11, 2011, 10:02:02 AM »
Yep I'd say so,
M is the voltage rating of the device.
Can't remember them all off hand but I think *J* means a 100volt rating.

Some makers use different codes but after a while you catch on to the tricks.
Phil.

Thanks!
Life is what you make it.
Still rockin' the Dean Markley K-20X
"New" amp: Fender Frontman 25 DSP (FM25DSP)
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DJPhil

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Re: "J20" (K-20X Preamp, only OD and with 071 instead of 072)
« Reply #34 on: January 11, 2011, 10:36:06 AM »
Wow you guys work fast! Well, that and I'm long winded too.  :duh
Here's a link to a page on cap codes, and a quick online calculator. The letter codes can be a number of things, but the letters used for voltage ratings are from an old military scale that's probably not used here. If so, it would mean 4KV rated cap!
The letter codes are often tolerance ratings. An 'M' would be +/- 20%, which is the standard tolerance for cheap caps. Sometimes you'll see a 'J' or 'K' rated cap (5% or 10%) to signify that the cap needs to be better than cheap. Capacitors will definitely teach you to forgive sloppy tolerances, especially when you imagine how many things out there are stuffed to the gills with +/- 20% parts and 1% resistors! It's a rare circuit that will need better than 5% on a cap, though it's a bit more common to need a well matched pair (twin T filters for example).

Included is a picture from when I thought I'd be the first to respond. The codes discussed above are commonly used for through hole small caps of all types.
You never know what you'll run into on an old schematic. :)

J M Fahey

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Re: "J20" (K-20X Preamp, only OD and with 071 instead of 072)
« Reply #35 on: January 11, 2011, 04:03:04 PM »
 :o
Been watching Australian floods on TV
WOW !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Becoming worried about Phatt and a couple other Aussies which frequent this virtual smoky joint.
All right pals ????
We want proof of life !!!
Post something or at least let go some bubbles, so we can see them in the surface.
Just in case, I'm getting my Scuba equipment ready.
Good luck. :tu:

joecool85

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Re: "J20" (K-20X Preamp, only OD and with 071 instead of 072)
« Reply #36 on: January 11, 2011, 04:30:45 PM »
:o
Been watching Australian floods on TV
WOW !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Becoming worried about Phatt and a couple other Aussies which frequent this virtual smoky joint.
All right pals ????
We want proof of life !!!
Post something or at least let go some bubbles, so we can see them in the surface.
Just in case, I'm getting my Scuba equipment ready.
Good luck. :tu:

No kidding, hope you guys are alright!
Life is what you make it.
Still rockin' the Dean Markley K-20X
"New" amp: Fender Frontman 25 DSP (FM25DSP)
thatraymond.com

DJPhil

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Re: "J20" (K-20X Preamp, only OD and with 071 instead of 072)
« Reply #37 on: January 11, 2011, 11:52:19 PM »
Yes, stay safe over there guys!
If you need help or need to check on someone you know I'd recommend contacting the Australian Red Cross. I worked with the Red Cross here locally when we had some flooding in 1993 and there's no better bunch of folks when you need a hand.

phatt

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Re: "J20" (K-20X Preamp, only OD and with 071 instead of 072)
« Reply #38 on: January 12, 2011, 11:05:16 AM »
First,,, Bubbles ,, yes I'm alive and well. ;D

2nd thanks *DJ Phil*. You are quite right the Letter is the Tolerance not the Voltage,,, late at night I get confused. :loco

And thanks All of you for your concern. :tu:

Nambour is about 80 mile north of the Capital of Queensland, Brisbane.

The great Dividing range runs right down the East Coast of Auz and when we get rain in Queensland on both sides of that range not only does it flood on the coastal towns but it also moves inland.

Some ends up in Lake Eyre ( it's a salt lake in the middle below sea level)

The rest ends up in the Murray River and the water from mid land Queensland actually takes 6 to 9 months to reach the mouth of the Murray River in South Australia.

When all the rivers from the middle of Qland join up, The Condermine, Darling,(to name 2 of many) they ultimately join into the Murray River.
That basin *is then* very close to the same size as the Missisippi. Of course nowhere near as much water flows but it is a very big system none the less.

Australia being so boring and flat in the middle the water just runs outwards and hence town after town gets flooded out.

By now some of you will know the Town of Towoomba because of that freak wave.
Well it's about 80mile west of Brisbane right on the very edge of the great diving range.

Yes I 've driven through that town many times,, that very street that you may have seen on TV.

My Father lived through the bad Floods of 1954 in my home town of Rockhampton which has also been Flooded again.
So yes you could say The East coast of Queensland is really behind the 8 ball.

I lived through the Brisbane flood 1974 so I know what they are in for. I helped many elderly folks in my area clean out the mess afterwards, The smell afterwards is horendous. I will never forget it.

Nambour got away with only some carpark being ripped away and 4 feet of mud in the main shops.  This town is very hilly up and down so water gets away fast.

It has been observed that this Flood may well be Australia's worst natural disaster and It is certainly starting to look that way. :'(

Having witnessed the 74 floods,,, I make a point of living on top of hills rather than low lying areas. 8|
Phil.

joecool85

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Re: "J20" (K-20X Preamp, only OD and with 071 instead of 072)
« Reply #39 on: January 12, 2011, 11:33:27 AM »
Having witnessed the 74 floods,,, I make a point of living on top of hills rather than low lying areas. 8|
Phil.

Good to hear you are alright, and learning all the time  :tu: lol

Back on topic, I have a vero layout almost complete for the whole K20-X preamp.  The original, as it is in the schematic, not with any of the changes we have talked about.
Life is what you make it.
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joecool85

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Re: "J20" (K-20X Preamp, only OD and with 071 instead of 072)
« Reply #40 on: January 14, 2011, 05:23:27 AM »
Alright, who wants to build a vero K20-X preamp?  It's all verified electronically on paper, but hasn't been built yet.
Life is what you make it.
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"New" amp: Fender Frontman 25 DSP (FM25DSP)
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joecool85

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Re: "J20" (K-20X Preamp, only OD and with 071 instead of 072)
« Reply #41 on: January 14, 2011, 11:25:55 AM »
Just realized teemu had a resistor and cap going to ground at the end of the circuit that I left off, how important would those be?
Life is what you make it.
Still rockin' the Dean Markley K-20X
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phatt

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Re: "J20" (K-20X Preamp, only OD and with 071 instead of 072)
« Reply #42 on: January 15, 2011, 09:44:49 AM »
Hi Joe,
         A suggestion if I may.
As a stand alone unit it would be wise to hang a buffer at the end of this.

It's a low imp tone stack which are not as lossy as high impeadance TStacks but just the same the circuit is some what dependant on what it plugs into.

A buffer will fix any interface issues that may arise.

There are a few well known pedals that do as you have done but it's not good design practise.
 Cheers Phil.

joecool85

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Re: "J20" (K-20X Preamp, only OD and with 071 instead of 072)
« Reply #43 on: January 15, 2011, 04:56:49 PM »
Hi Joe,
         A suggestion if I may.
As a stand alone unit it would be wise to hang a buffer at the end of this.

It's a low imp tone stack which are not as lossy as high impeadance TStacks but just the same the circuit is some what dependant on what it plugs into.

A buffer will fix any interface issues that may arise.

There are a few well known pedals that do as you have done but it's not good design practise.
 Cheers Phil.

Ok, what about the resistor and cap that teemu had on the end of the circuit that I didn't add in?  The schematic had a resistor inline as well as one to ground and a cap to ground originally right before going into the poweramp circuit - should I put these in?
Life is what you make it.
Still rockin' the Dean Markley K-20X
"New" amp: Fender Frontman 25 DSP (FM25DSP)
thatraymond.com

DJPhil

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Re: "J20" (K-20X Preamp, only OD and with 071 instead of 072)
« Reply #44 on: January 15, 2011, 09:07:24 PM »
Ok, what about the resistor and cap that teemu had on the end of the circuit that I didn't add in?
I went back and found a schematic in this post, let me know if I should be looking at another.
R12 and C11?
I believe these act as a lowpass filter and help set the output impedance. It starts rolling the impedance down at about 14kHz, and this helps keep ultrasonics out of the following stage (presumably a power amp) which aids in stability. It certainly wouldn't hurt to put it in, and if need be you can just solder the parts to the output jack.

The schematic had a resistor inline as well as one to ground and a cap to ground originally right before going into the poweramp circuit - should I put these in?
I'm not sure about this one. Do you mean preamp as opposed to power amp? Could you say which components in the above schematic?

Hope that helps. :)

 

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