Millennium bypass transistor

[demonstar]

Hi, in the millennium bypass section of this pedal...

"http://www.tonepad.com/getFile.asp?id=87"

... are there any alternatives for the 2n5485 transistor because all the other parts are available locally except that one and it'd be annoying to order just one part online so I'd rather replace it with an alternative. Does anybody know of one? thanks.

[jpm83]

I think that 2N5457 and J201 would work fine in there. correct me if I'm wrong.

Janne

[demonstar]

I've been using a 2n3904 and it's not working. I think I got totally the wrong type of transisitor. I think i'm going to try a bf245c.
Should this work?

[R.G.]

You got totally the wrong type of transistor. 2N3904 is a bipolar transistor, 2N5485 is JFET. Their primary similarities are that the are both made from silicon and both have the same package type. Otherwise, they are completely different.

If you can get one, try a BF244B or BF244C. The 245C might work, can't tell because JFETs have a wide device-to-device variation.

[demonstar]

O.k. thanks. At least you've confirmed why it's not working.

I believe it's a JFET i need. The recommended ones aren't available local. I'd be buying from maplin and the BF245C is. I think I'll do a bit more research then if I'm none the wiser go for the BF245C because thats the only JFET available there.

Thanks anyway!

[Hambo]

I never had much luck with the mill1 and any of Maplins Jfets. It always seems to stay on dimly for me, or not much difference between on and off or some such. As a bright spark pointed out to me when I started at this.. maplin sell 2n7000 mosfets, use them to do the millennium 2.. absolutely no hassle there. Almost everything I make now has the millennium2 in it.

Or of course order 3pdt switches from Banzai.

[demonstar]

Next time I shall go with millennium 2 but I've made a circuit with one now. I'm going to give the BF245C a go or whatever it is and hope that the really low resistor for the LED will keep it bright.

I'm using a 130 ohm resistor to run the LED just under it's maximum. What resistors were you using for the millennium 1, Hambo? I think the 2k2 they suggest would be very dim.
I'll give it a go but if your right (which you probably are, I'll have problems.)

I'd mail order one for this circuit.

[Hambo]

Erm, most times Ive done the limiting resistor calculations its come out at 470ohm for a regular LED on 9V.. I've gone with that with no problems thus far although I think its considered a bit shady, most people seem to use 4.7k 
I think you be ok with 1k 1.5k something like that.

If you mean R2 to dim the LED I have no idea, I never used that, only the series 148/914 diodes approach.

[boyersdad]

I find that with a 2n5457, or J201, there is no off-state glow, but sometimes with a 2n5485, there's a little bit, so I just shunt the LED with a 2k2 and problem solved. I've never had the problems some people seem to have with dimming, fading on, and sticking off or on.... All my transistors/FETS etc come from smallbear, if that makes any difference.

[demonstar]

Thanks to all that helped! I think I'm going to buy some J201s then I'm good to go.

[boyersdad]

With a J201 you should be able to rock it right out of the box. If you do get some off-state glow (ie the LED is dim while supposed to be off) solder a leg of a 2.2k resistor across each lead on the LED and that should get rid of your problem.

I made a revised version of R.G's millenium PCB to include two pads for this shunt resistor, just incase. I'll see if I can find it if you're interested.

[demonstar]

I just thought I'd report back that I've been to maplin and got a BF245C and it does NOT work! The LED just stays on permenant. 

So Don't use the BF245C from maplin for millenium bypass one!