Tronographic Rusty Box - transistor substitutions

[patricks]

Hi all,

I'm about to embark on a build of the Tronographic Rusty Box (http://tagboardeffects.blogspot.com.au/2014/03/tronographic-rusty-box.html), but I've hit a snag with parts.
Can anyone recommend a substitute for the 2N5245 and MPS8598? Neither Mouser, Tayda, nor any of my local electronics shops has them in stock. I saw the earlier post about subbing an SK170 or BF256B, but I'm not having any luck finding them, either.

With the zeners, will any 15V zener do, or do they have to be the NTE5024A (can't find them in stock, either)?

Cheers, Pat

[UKToecutter]

Hi Pat

You can get 2N5245 at http://www.goldmine-elec-products.com @ $1 for 10.
The MPS8598 you can replace with an MPSA55.
The Zener can be any 1/2W 15V like 1N5245B which is easily obtainable from Mouser.

Be sure to check the pin assignments on the MPSA55 as they may not be the same.

Good luck with your build

[patricks]

Fantastic, thanks very much!

[PRR]

> SK170 or BF256B

The "right" numbers will be 2SK170 and 2BF256.

Japanese transistor numbers start with "2", but this is often omitted on plans since everybody who uses Japanese transistors all day long "knows that".

2SK170 is indeed hard to find. If we could see the circuit (not just a layout) we might guess better.

[patricks]

Ah, thanks for that. The Rusty Box is a clone of the Traynor TS-50B amp, here's the schematic: http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/RustyBox/traynor-bass-ts50b-amplifier-schematic.png

[mth5044]

Man, is that really all that amp is? What's the catch? You can get +/- 15V from a 16AC adapter. A bass amp without having to bother with mains wiring? I have to be missing something!

EDIT: Maybe it's just a preamp  

Anyway, here is some info that PRR posted on GroupDIY about the transistors from late 2013.

Any N-type JFET, though higher Vth is better.

If leads are very short (all inside a pedal), replace the JFET with a mechanical switch.

The 6-pack splits lows, highs, and mids and distorts them separate. Any PNP Silicon part.

The emitter follower before that is any non-sucky NPN.

The splitting of frequencies is pretty nifty.

Double EDIT: That schematic you posted has been mod'd to remove the much more complicated power amp. NOW it makes sense.

[patricks]

Awesome, thanks! I've got done 2N5952s from a phase 90 project sitting round, so I'll try one of those and see what I can rustle up in the way of PNPs.
Yeah, the frequency splitting of definitely pretty cool

[bluebunny]

> SK170 or BF256B

The "right" numbers will be 2SK170 and 2BF256.

BF256B is an N-channel JFET (EECA naming).  (This datasheet came from Farnell, if that's any use to you.)

[duck_arse]

a local parts house once had 'J210' on special, as low power mosfets. so I got some, they turned out to be "J210", jfets, and quite nice.

10 for a dollar fets .... drools .....

[patricks]

Resurrecting the thread with another question -
The commercial stomp has a balanced output for use as a DI, so I'd like to swap the TL071 for a TL072 and use the other half to add in this unbalanced-to-balanced circuit:


Should I put R1 (10k) in series with the 50k "master volume" pot in the original schematic to maintain a minimum 10k input impedance?
Cheers
Pat