madbeanpedals::forum

Projects => Tech Help - Projects Page => Topic started by: Gilmourisgod on September 30, 2013, 04:47:41 PM

Title: Harbinger One BOM Problem
Post by: Gilmourisgod on September 30, 2013, 04:47:41 PM
The Harbinger One BOM lists Q14 transistor as "J201", can't get a coherent hit on on that keyword in Mouser. Tried searching within Fairchild Semiconductors, got a "JFET N-Channel Transistor General Purpose" Mouser #512-MMBFJ201", but it doesn't look anything like the component symbol on the PCB, which looks like a standard cylindrical transistor with one flat side. Can anybody help me out on this one?
Title: Re: Harbinger One BOM Problem
Post by: Gilmourisgod on September 30, 2013, 05:07:28 PM
Found this Fairchild data sheet on line, looks like the J201 comes in two configurations, is the TO-92 version the correct component?
http://www.fairchildsemi.com/ds/MM/MMBFJ201.pdf
Title: Re: Harbinger One BOM Problem
Post by: kothoma on September 30, 2013, 05:16:08 PM
Yup, you'll want the TO-92.
Title: Re: Harbinger One BOM Problem
Post by: madbean on September 30, 2013, 05:26:22 PM
You won't find a TO-92 J201 on Mouser. It is no longer in production (although pedal builders still use them). If you just need the one, PM your address and I will send you one. But, I do advise getting some on hand for future builds. You can still get them in quantity on smallbear and eBay.

Also, in the case of the Harbinger, you could use a 2n5457, or similar JFET. It's only used as a buffer.
Title: Re: Harbinger One BOM Problem
Post by: Gilmourisgod on September 30, 2013, 06:39:18 PM
Madbean
Thanks for the response. I have to buy a few of the components from Smallbear anyway, I'll see if they have them available.
Title: Re: Harbinger One BOM Problem
Post by: madbean on September 30, 2013, 09:16:24 PM
It's unfortunate, but the situation we have to deal with. We love those through hole JFETS for guitar pedals, but it will get increasingly difficult to get them in quantity cheaply. Eventually, we'll have to go surface mount if we want to use them.
Title: Re: Harbinger One BOM Problem
Post by: kothoma on October 01, 2013, 10:13:02 AM
I think I've seen tiny little converter boards (SMD -> 3 pins) somewhere?

Edit: Right, layout and how-to video:  http://www.diyguitarpedals.com.au/shop/index.php?main_page=product_info&cPath=6&products_id=52
Title: Re: Harbinger One BOM Problem
Post by: toddvirgil on October 01, 2013, 02:14:12 PM
I pick up my J201's at Tayda -- they say they are TO-92 -- does anyone run into problems with these?

http://www.taydaelectronics.com/j201-jfet-n-channel-amplifier-transistor.html

T
Title: Re: Harbinger One BOM Problem
Post by: Rockhorst on October 01, 2013, 02:40:11 PM
I've heard multipe reports stating that they are out of spec or at the very limits of the spec sheets. Haven't tried them personally, I have a nice back stash for now.
Title: Re: Harbinger One BOM Problem
Post by: Gilmourisgod on October 01, 2013, 04:46:31 PM
On another note, I assume the volume and intensity pots are linear taper, not audio taper? Excuse my noobish ignorance. I think that's what I used on the Forumvibe.
Title: Re: Harbinger One BOM Problem
Post by: kothoma on October 01, 2013, 07:44:55 PM
Yes, B stands for linear. And Speed is a reverse logarithmic dual pot.