Author Topic: iRig (with DIY impedance matching cable?)  (Read 142929 times)

BoxOfSnoo

Re: iRig (with DIY impedance matching cable?)
« Reply #60 on: June 11, 2011, 08:28:57 PM »
Found this schematic the other day, almost identical to the ones above.  http://sgitornado.altervista.org/diyirig.html

He doesn't include the resistor off the tip of the guitar input, but looks pretty clear to follow. I might have to try this now...
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darzzydarzz

Re: iRig (with DIY impedance matching cable?)
« Reply #61 on: June 18, 2011, 08:47:57 AM »
Found this schematic the other day, almost identical to the ones above.  http://sgitornado.altervista.org/diyirig.html

He doesn't include the resistor off the tip of the guitar input, but looks pretty clear to follow. I might have to try this now...

going to give this a go but being a bit of a noob, can someone help me with the tranny pins on this schematic? source in from guitar, drain to mic, gate to the 1.2k resistor?

BoxOfSnoo

Re: iRig (with DIY impedance matching cable?)
« Reply #62 on: June 18, 2011, 03:39:17 PM »
I threw this together today, does it look right?



I have 100pF and 500pF silver mica caps, but not a 470pF.  a) can I sub in the 500 safely for the 470?  What does it accomplish?  b) are silver mica overkill/unnecesary for this project?
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Govmnt_Lacky

Re: iRig (with DIY impedance matching cable?)
« Reply #63 on: June 18, 2011, 03:43:18 PM »
Might be a noobish questions but...  ::)

What is a Ferrite Bead? What does it look like and what purpose does it serve?

 :icon_redface:
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Govmnt_Lacky

Re: iRig (with DIY impedance matching cable?)
« Reply #64 on: June 18, 2011, 03:49:07 PM »
Might be a noobish questions but...  ::)

What is a Ferrite Bead? What does it look like and what purpose does it serve?

 :icon_redface:

Nevermind... followed my own advice and used Google  :icon_redface:
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
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darzzydarzz

Re: iRig (with DIY impedance matching cable?)
« Reply #65 on: June 18, 2011, 10:00:36 PM »
Found this schematic the other day, almost identical to the ones above.  http://sgitornado.altervista.org/diyirig.html

He doesn't include the resistor off the tip of the guitar input, but looks pretty clear to follow. I might have to try this now...

going to give this a go but being a bit of a noob, can someone help me with the tranny pins on this schematic? source in from guitar, drain to mic, gate to the 1.2k resistor?

this circuit works great for me, left out the ferrite bead :) oh and used an mpf102 as couldnt get anything else from my local shop.
« Last Edit: June 18, 2011, 10:03:14 PM by darzzydarzz »

PRR

Re: iRig (with DIY impedance matching cable?)
« Reply #66 on: June 19, 2011, 01:50:25 AM »
 > a) can I sub in the 500 safely for the 470? 
 
Certainly.
 
 > What does it accomplish?
 
Reduces radio reception/transmission.
 
 > b) are silver mica overkill/unnecesary for this project?
 
Yes (but what the heck).

Your tin roof is loose, buzzes in gusty wind. Put a rock on it. Big enough to damp the buzz, not big enough to dent the roof, but you don't fret whether it is a 470mm rock or a 500mm rock, granite or shale. I'm sure Apple's builders use ceramic; in this value ceramic is a near-perfect cap. They used 470 because that's how we number things since the 1960s; Silver Mica has been hanging around since the 1950s.

If you build an amp with a BRITE switch, I'd use the SM there. But mostly cuz it looks good, I suspect it sounds the same as ceramic.

soggybag

Re: iRig (with DIY impedance matching cable?)
« Reply #67 on: September 20, 2011, 05:22:01 PM »
I threw this together today, does it look right?



I have 100pF and 500pF silver mica caps, but not a 470pF.  a) can I sub in the 500 safely for the 470?  What does it accomplish?  b) are silver mica overkill/unnecesary for this project?

What transistor are you using for this? The thread lists a couple possible choices J201 and MPF102. The Japanese site used a BF part number. I noticed they had SHO in one of the captions. This was giving me the impression it was a MosFET.

BoxOfSnoo

Re: iRig (with DIY impedance matching cable?)
« Reply #68 on: September 20, 2011, 05:36:13 PM »
I threw this together today, does it look right?



I have 100pF and 500pF silver mica caps, but not a 470pF.  a) can I sub in the 500 safely for the 470?  What does it accomplish?  b) are silver mica overkill/unnecesary for this project?

What transistor are you using for this? The thread lists a couple possible choices J201 and MPF102. The Japanese site used a BF part number. I noticed they had SHO in one of the captions. This was giving me the impression it was a MosFET.

I used a j201, but I never got it working on my breadboard, so I never even got this far... Let me know if it works for anyone.

I was just going to buy one, but now I notice Line6 has come out with a new dock-connector based interface that looks pretty nice. Maybe I'll hold out for that one.  If I can get this beast going then I'll have something to tide me over.
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Evil-Smurf

Re: iRig (with DIY impedance matching cable?)
« Reply #69 on: October 06, 2011, 06:44:10 PM »
i am a total noob in this sorry still trying to read and understand everything and hope to improve as i go because it all very interesting to me.
i have been at the store today looking for parts and a guy there told me that instead of bf245c i can use 2n7000? could that be right?

PRR

Re: iRig (with DIY impedance matching cable?)
« Reply #70 on: October 06, 2011, 10:46:09 PM »
No.

Skruffyhound

Re: iRig (with DIY impedance matching cable?)
« Reply #71 on: October 07, 2011, 06:24:56 AM »
Lol. Succinct.
The guy in the store often just wants to sell you something in my experience.
Get the datasheets here for example : http://www.ic-on-line.cn/ , and you can compare their basic characteristics yourself.

robmdall

Re: iRig (with DIY impedance matching cable?)
« Reply #72 on: October 07, 2011, 07:51:24 AM »
Nice website Skruffy!

Evil-Smurf

Re: iRig (with DIY impedance matching cable?)
« Reply #73 on: October 07, 2011, 01:32:00 PM »
Sorry to ruin the thread with such a novice question. Thanks for the site although i don't understand a thing at these data sheets even I get that these are totally different... I guess I got lots to learn before I can do anything here.

Skruffyhound

Re: iRig (with DIY impedance matching cable?)
« Reply #74 on: October 07, 2011, 05:44:56 PM »
 There's a lot on those datasheets I don't understand properly, but you can compare some stuff. Read up for yourself, but don't be shy to ask questions, people here are normally glad to help. Paul was uncharacteristically brief, why I laughed.
If you don't like the datasheets do a search on the forum. I just checked and J201, BF245A and possibly 2SK117 turn up in threads as substitutes. The 2N7000 is a mosfet which is a different beast than you want in this application.

@Rob. Thanks, all my own work too! .... ::)

BoNin

Re: iRig (with DIY impedance matching cable?)
« Reply #75 on: October 16, 2011, 10:54:41 AM »
ive read all of the post and im confused what schem shall i follow, also because i cant find the j201 and bf245a these components here... please help..

Keeb

Re: iRig (with DIY impedance matching cable?)
« Reply #76 on: November 21, 2011, 05:44:19 PM »
Hi guys!

Sorry for necroposting like this but I just wanted to let you know that I built it according to the schematic above http://sgitornado.altervista.org/diyirig.html but changed the transistor to a MPF102.
I built it on this layout and it works like a charm!



Edit; For clarity I might add that the iPhone plug (from bottom to top) goes mic - ground - right - left.
« Last Edit: November 21, 2011, 05:45:52 PM by Keeb »

Skruffyhound

Re: iRig (with DIY impedance matching cable?)
« Reply #77 on: November 25, 2011, 06:57:06 PM »
Nice one.

Govmnt_Lacky

Re: iRig (with DIY impedance matching cable?)
« Reply #78 on: November 26, 2011, 04:24:02 PM »
How crucial is the ferrite bead?

Can it be omitted? And if it was, what are the possible side-effects  :icon_eek:

Also, can anyone recomend a good US based contact for the 4 pole 3.5m plug that is used?
« Last Edit: November 26, 2011, 04:54:10 PM by Govmnt_Lacky »
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DavenPaget

Re: iRig (with DIY impedance matching cable?)
« Reply #79 on: November 26, 2011, 04:52:22 PM »
How crucial is the ferrite bead?

Can it be omitted? And if it was, what are the possible side-effects  :icon_eek:
Flitering DC , i guess .
Or could be for flitering nasty artifacts .
Hiatus